# AC 25-17A: Transport Airplane Cabin Interiors Crashworthiness Handbook

- Type: Advisory circular (guidance, not mandatory unless a rule or AD requires it)
- Status: Current
- Approved: May 18, 2009
- Last reviewed: June 27, 2016
- Family: AC 25-17
- Cancels: [AC 25-17](https://openairdocs.org/ac/25-17)
- 14 CFR parts: 25
- 14 CFR sections: [25.561](https://www.ecfr.gov/current/title-14/section-25.561), [25.562](https://www.ecfr.gov/current/title-14/section-25.562), [25.772](https://www.ecfr.gov/current/title-14/section-25.772), [25.783](https://www.ecfr.gov/current/title-14/section-25.783), [25.785](https://www.ecfr.gov/current/title-14/section-25.785), [25.787](https://www.ecfr.gov/current/title-14/section-25.787), [25.789](https://www.ecfr.gov/current/title-14/section-25.789), [25.791](https://www.ecfr.gov/current/title-14/section-25.791), [25.793](https://www.ecfr.gov/current/title-14/section-25.793), [25.801](https://www.ecfr.gov/current/title-14/section-25.801), [25.803](https://www.ecfr.gov/current/title-14/section-25.803), [25.795](https://www.ecfr.gov/current/title-14/section-25.795), [25.805](https://www.ecfr.gov/current/title-14/section-25.805), [25.807](https://www.ecfr.gov/current/title-14/section-25.807), [25.809](https://www.ecfr.gov/current/title-14/section-25.809), [25.810](https://www.ecfr.gov/current/title-14/section-25.810), [25.811](https://www.ecfr.gov/current/title-14/section-25.811), [25.812](https://www.ecfr.gov/current/title-14/section-25.812), [25.813](https://www.ecfr.gov/current/title-14/section-25.813), [25.815](https://www.ecfr.gov/current/title-14/section-25.815), [25.817](https://www.ecfr.gov/current/title-14/section-25.817), [25.819](https://www.ecfr.gov/current/title-14/section-25.819), [25.851](https://www.ecfr.gov/current/title-14/section-25.851), [25.853](https://www.ecfr.gov/current/title-14/section-25.853), [25.854](https://www.ecfr.gov/current/title-14/section-25.854), [25.855](https://www.ecfr.gov/current/title-14/section-25.855), [25.856](https://www.ecfr.gov/current/title-14/section-25.856), [25.857](https://www.ecfr.gov/current/title-14/section-25.857), [25.869](https://www.ecfr.gov/current/title-14/section-25.869), [25.1307](https://www.ecfr.gov/current/title-14/section-25.1307), [25.1359](https://www.ecfr.gov/current/title-14/section-25.1359), [25.1413](https://www.ecfr.gov/current/title-14/section-25.1413), [25.1415](https://www.ecfr.gov/current/title-14/section-25.1415), [25.1421](https://www.ecfr.gov/current/title-14/section-25.1421), [25.1423](https://www.ecfr.gov/current/title-14/section-25.1423), [25.1439](https://www.ecfr.gov/current/title-14/section-25.1439), [25.1447](https://www.ecfr.gov/current/title-14/section-25.1447), [25.1457](https://www.ecfr.gov/current/title-14/section-25.1457), [25.1411](https://www.ecfr.gov/current/title-14/section-25.1411), [25.1541](https://www.ecfr.gov/current/title-14/section-25.1541), [25.1557](https://www.ecfr.gov/current/title-14/section-25.1557), [25.1561](https://www.ecfr.gov/current/title-14/section-25.1561)
- Pages: 893
- PDF: https://openairdocs.org/files/sha256/f8/63/f8633972c79cbf69f5c5196a3e98eaba56160e1554a9f4dec083c9eaf4fffd5f
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/286D3183A8A1D575862575C80048412B.0001
- DRS record last changed: October 23, 2026
- Page: https://openairdocs.org/ac/25-17

## Versions

- [AC 25-17A](https://openairdocs.org/ac/25-17) (Current), approved May 18, 2009, 893 pages
- [AC 25-17](https://openairdocs.org/ac/25-17?v=4869435CE599B865862569B20075289A) (Historical), approved Jul 15, 1991, 176 pages

## ADs that cite it (1)

- [AD 2017-09-09](https://openairdocs.org/ad/2017-09-09): Passenger Compartment Equipment · Boeing 717-200, MD-90-30, CL-600-2C10 (Regional Jet Series 700) and 17 more. Effective Jun 28, 2017

## Text

Each page's text from the PDF; open the PDF at a page with #page=N. Some pages are OCR from the scanned FAA advisory circular. OCR can misread letters and numbers. Those pages are marked (OCR).

### Page 1

U.S. Department of Transportation Federal Aviation Administration Advisory Circular Subject: Transport Airplane Cabin Interiors Crashworthiness Handbook Date: 05/24/16 Initiated By: ANM-115 AC No: 25-17A Change: 1

1. PURPOSE. This change clarifies guidance for the head strike zone, to standardize application of the head strike zone when showing compliance with Title 14, Code of Federal Regulations (14 CFR) 25.785(b) and (d). Protecting the occupant’s head from serious injury requires determination of the zone that the head could strike, i.e., the head strike zone. Because inertial forces will cause the head to travel along the longitudinal axis of the airplane, when applicants show compliance for the inertia forces specified in §§ 25.561 and 25.562, the head strike zone should be oriented in the same direction (the airplane longitudinal axis) as the forces are applied. The guidance in the previous release of this AC did not state this to be the case, so some applicants misinterpreted the head strike direction to be aligned with the seat, regardless of angle of installation of the seat and the inertial forces. This interpretation was not consistent with § 25.785, which protects occupants in the emergency landing conditions specified in §§ 25.561 and 25.562. Additionally, a literal interpretation of the head strike zone depicted in AC 25-17A would include portions of the occupant’s own seat very close to the seat back and seat bottom cushions. This part of the zone is not considered likely to cause serious injury to the occupant’s head and has been removed from the zone.

2. PRINCIPAL CHANGES. Change 1 updates AC 25-17A, Transport Airplane Cabin Interiors Crashworthiness Handbook, dated May 18, 2009. We have added the change number and date of revision at the top of each changed page. We have also marked the changes with a vertical change bar in the margin. Specifically, Change 1 incorporates the following changes:

a. On pages 46, 59, 72, 85, 98, 112, 126, and 140, the definition of the head strike zone is modified to specify the zone is in the direction of the airplane longitudinal axis, and does not include those portions of the occupant’s own seat that are very close to the seat back and seat bottom cushions.

b. On pages 47, 60, 73, 86, 99, 113, 127 and 141, the figure showing the head strike zone is modified to show the zone is in the direction of the airplane longitudinal axis, and does not include those portions of the occupant’s own seat that are very close to the seat back and seat bottom cushions.

### Page 2 (OCR)

Page Control Chart Remove Pages Dated Insert Pages Dated 46 and 47. 05/18/2009 46 and 47. .. 05/24/2016 59 and 60 . 05/18/2009 59 and 60. .. 05/24/2016 72 and 23 .. 05/18/2009 72 and 23. .. 05/24/2016 85 and 86 05/18/2009 85 and 86.. .. 05/24/2016 98 and 99 .. 05/18/2009 98 and 99. .. 05/24/2016 112 and 113 05/18/2009 112 and 113.. .. 05/24/2016 126 and 127... .. 05/18/2009 126 and 127... .. 05/24/2016 140 and 141 .. .. 05/18/2009 140 and 141.. ... 05/24/2016 If you have suggestions for improving this AC, you may use the Advisory Circular Feedback form at the end of this AC.

Michael Feas Michael Kaszycki Acting Manager, Transport Airplane Directorate Aircraft Certification Service

### Page 3

Subject: TRANSPORT AIRPLANE CAB

**IN INTERIORS**

CRASHWORTHINESS HANDBOOK Date: 5/18/2009 Initiated By: ANM-110 AC No: 25-17A Change:

l. PURPOSE. This Advisory Circular (AC) provides acceptable certification methods, but not necessarily the only acceptable methods, for demonstrating compliance with the crashworthiness requirements of part 25, as amended through Amendment 25-112, of Title 14 of the Code of Federal Regulations (14 CFR) for transport category airplanes. The guidance in this AC is not mandatory nor a regulation.

**2. APPLICABILITY.**

a. Available guidance pertaining to part 25 is presented according to the amendment level of part 25 to which it applies. For modified airplanes certificated under part 25, the pertinent guidance may be obtained from this AC by reference to the applicable amendment level.

(Compliance with later rules may be required in accordance with §§ 21.101(a) and 25.2, or with applicable operating rules as noted above.) Additional guidance may be included in this AC that pertains to either prior amendments or sections that have not been modified. This guidance has been developed to address issues that either have developed since the original issue of this AC, or were inadvertently omitted. The guidance presented in this AC for part 25 airplanes may be used for airplanes certificated under CAR 4b to the extent the rules contained in the older certification bases are the same as those of part 25. The guidance presented herein applies to part 25 through Amendment 25-112.

b. The guidance provided in this document is directed to airplane manufacturers, modifiers, foreign regulatory authorities, and FAA transport airplane type certification engineers, and their designees.

c. This material is neither mandatory nor regulatory in nature and does not constitute a regulation. It describes acceptable means, but not the only means, for demonstrating compliance with the applicable regulations. The FAA will consider other methods of demonstrating compliance that an applicant may elect to present. While these guidelines are not mandatory, they are derived from extensive FAA and industry experience in determining compliance with the relevant regulations. On the other hand, if we become aware of circumstances that convince us that following this AC would not result in compliance with the applicable regulations, we will

### Page 4

ii not be bound by the terms of this AC, and we may require additional substantiation or design changes as a basis for finding compliance.

d. This material does not change, create any additional, authorize changes in, or permit deviations from, regulatory requirements.

3. CANCELLATION. ADVISORY CIRCULAR 25-17, Transport Airplane Cabin Interiors Crashworthiness Handbook, dated July 15, 1991, is canceled.

**4. BACKGROUND.**

a. Crashworthiness, as applied to airplane cabin interiors, denotes the incorporation in basic design of considerations pertinent to the protection of airplane occupants in a “survivable crash environment.” A survivable crash environment prevails when the cabin occupants are subjected to crash forces within human tolerance levels, and the structural integrity of the passenger space remains intact such that the occupants can rapidly evacuate the airplane. Structural design for airplane safety has embodied airworthiness and crashworthiness design objectives to varying degrees. Airworthiness design objectives pertain to the ability of the airframe to withstand design loads, or to maintain safety of flight of the airplane relative to the operational environment. Crashworthiness design objectives pertain to safety of the occupants relative to the airplane. Some aspects of crashworthiness, e.g., fuel tank/system design, fuselage deformation and prevention of post-crash fires, are beyond the scope of this AC.

b. Since the inception of federal civil aircraft certification standards, prime emphasis has focused on design for airworthiness, with a preference for application of static load tests, as opposed to dynamic. The emphasis on airworthiness is understandable, since structural and handling deficiencies were inherent in early airplane designs. Further, there was not enough theoretical or technical knowledge available from service experience to generate meaningful design parameters for crash survival. Likewise, in early design, as now, dynamic criteria have been difficult to ascertain. Except for standards for seat belts, seat static load requirements, and exits, crashworthiness was given very little attention until the post-World War II period. During subsequent years, the regulatory process expanded emphasis on crashworthiness. A significant change occurred in 1967, when the Federal Aviation Administration (FAA) promulgated a series of crashworthiness standards affecting transport category airplanes. Further changes were implemented in 1972. As reflected in the rule changes of 1967, the FAA's approach to crashworthiness principally involved three areas of concern: (1) protection of airplane occupants from crash impact; (2) minimizing development and severity of potential crash fire; and (3) rapid evacuation of airplane occupants. Each of these factors has been a focal point in the periodic upgrading of regulatory standards.

c. Part 4b of the former Civil Air Regulations (CAR) was recodified in 1965 as part 25 of 14CFR. The related policy material contained in Civil Aeronautics Manual (CAM) 4b was applicable to part 25 as originally recodified and to current part 25 except in areas that have been amended since recodification. Those policies are included in this AC and listed as guidance applicable to the original recodified version of part 25.

### Page 5

iii

d. This AC consists of the original part 25 of 14 CFR (1965 recodified version), followed by appropriate guidance. Amendments to the regulation are presented in chronological order, with those paragraphs changed by the amendment enclosed within [ ]. The complete regulation text is provided for each amendment. If guidance exists for an amended rule, it is presented following the regulation paragraphs. Guidance from previous amendments to the rule are reprinted for each applicable amendment of the regulation. At the end of the guidance paragraph within ( ) is the amendment level when the guidance was first applicable.

e. Certain changes may require compliance with rules later than the type certification basis.

For example:

(1) § 21.101 the change product rule – helps determine when amended and supplemental type certification products need to utilize later amendment levels for areas of change.

(2) § 25.2 special retroactive requirements – requires, in part, that applicants for amended or supplemental type certification projects need to utilize amendment levels which may be later than those in the type certification basis of the airplane when the projects will result in an increase in the maximum seating capacity of the airplanes.

(3) Operating rules §§ 91.58, 121.310, 121.311, 121.312, 121.317, 121.318, 121.319,

125.113, 135.170, and Appendix A of part 135 of the CFR – require, in some cases, that airplanes operating under these parts have materials or equipment installed which are in excess of the type certification basis of the airplanes.

f. Advisory circulars listed in Appendix 3 may be revised after issuance of this AC. The latest available revision of the listed AC should be used.

/s/ Ali Bahrami Ali Bahrami Manager, Transport Airplane Directorate Aircraft Certification Service,

### Page 6

iv

TABLE OF CONTENTS Paragraph Page 1 – 10 [RESERVED] SECTION 25.561 EMERGENCY LANDING CONDITIONS

**GENERAL**

11. Regulation in Effect at Adoption of Part 25. 1

12. Amendment 25-23, Effective May 8, 1970. 2

13. Amendment 25-64, Effective June 16, 1988. 3

14. Amendment 25-91, Effective July 29, 1997. 4 15 – 20. [RESERVED] SECTION 25.562 EMERGENCY LANDING DYNAMIC

**CONDITIONS**

21. Section 25.562 Did Not Exist Prior to Amendment 25-64. 7

22. Amendment 25-64, Effective June 16, 1988. 7 23 – 40. [RESERVED] SECTION 25.772 PILOT COMPARTMENT DOORS

41. Section 25.772 Did Not Exist Prior to Amendment 25-33. 13

42. Amendment 25-33, Effective October 21, 1972. 13

43. Amendment 25-47, Effective December 24, 1979. 13

44. Amendment 25-72, Effective August 20, 1990. 15

45. Amendment 25-106, Effective January 15, 2002. 16 46 - 60. [RESERVED] SECTION 25.783 DOORS

61. Regulation in Effect at Adoption of Part 25. 19

62. Amendment 25-15, Effective October 24, 1967. 22

63. Amendment 25-23, Effective May 8, 1970. 25

64. Amendment 25-54, Effective October 14, 1980. 28

65. Amendment 25-72, Effective August 20, 1990. 32

66. Amendment 25-88, E ffective December 9, 1996. 36 67 - 80. [RESERVED] SECTION 25.785 SEATS, BERTHS, SAFETY BELTS, AND

**HARNESSES**

81. Regulation in Effect at Adoption of Part 25. 41

82. Amendment 25-15, Effective October 24, 1967. 53

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v

83. Amendment 25-20, Effective April 23, 1969. 66

84. Amendment 25-32, Effective May 1, 1972. 79

85. Amendment 25-51, Effective March 6, 1980. 92

86. Amendment 25-64, Effective June 16, 1988. 106

87. Amendment 25-72, Effective August 20, 1990. 120

88. Amendment 25-88, Effective December 9, 1996. 134 89 - 100. [RESERVED] SECTION 25.787 STOWAGE COMPARTMENTS

101. Regulation in Effect at Adoption of Part 25. 149

102. Amendment 25-32, Effective May 1, 1972. 149

103. Amendment 25-38, Effective February 1, 1977. 152

104. Amendment 25-51, Effective March 6, 1980. 155 105 - 120. [RESERVED] SECTION 25.789 RETENTION OF ITEMS OF MASS

121. Section 25.789 Did Not Exist Prior To Amendment 25-32. 159

122. Amendment 25-32, Effective May 1, 1972. 159

123. Amendment 25-46, Effective December 1, 1978. 159 124 - 140. [RESERVED] SECTION 25.791 PASSENGER INFORMATION SIGNS

141. Section 25.791 Did Not Exist Prior to Amendment 25-32. 161

142. Amendment 25-32, Effective May 1, 1972. 161

143. Amendment 25-72, Effective August 20, 1990. 162 144 - 160. [RESERVED] SECTION 25.793 FLOOR SURFACES

161. Section 25.793 Did Not Exist Prior to Amendment 25-51. 165

162. Amendment 25-51, Effective March 6, 1980. 165 163 - 210. [RESERVED] SECTION 25.795 SECURITY CONSIDERATIONS

211. Section 25.795 Did Not Exist Prior to Amendment 25-106. 167

212. Amendment 25-106, Effective January 15, 2002. 167

213 - 250. [RESERVED]

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vi SECTION 25.801 DITCHING

251. Regulation in Effect at Adoption of Part 25. 169

252. Amendment 25-72, Effective August 20, 1990. 171 253 - 270. [RESERVED] SECTION 25.803 EMERGENCY EVACUATION

271. Regulation In Effect At Adoption Of Part 25. 175

272. Amendment 25-1, Effective June 7, 1965. 175

273. Amendment 25-15, Effective October 24, 1967. 176

274. Amendment 25-17, Effective June 20, 1968. 180

275. Amendment 25-20, Effective April 23, 1969. 185

276. Amendment 25-32, Effective May 1, 1972. 190

277. Amendment 25-46, Effective December 1, 1978. 195

278. Amendment 25-72, Effective August 20, 1990. 201 279 - 300. [RESERVED] SECTION 25.805 FLIGHTCREW EMERGENCY EXITS

301. Amendment 25-72, Effective August 20, 1990. 205

302. Amendment 25-72, Effective August 20, 1990. 205 303 - 320. [RESERVED] SECTION 25.807 PASSENGER EMERGENCY EXITS

321. Regulation in Effect at Adoption of Part 25. 207

322. Amendment 25-15, Effective October 24, 1967. 211

323. Amendment 25-32, Effective May 1, 1972. 219

324. Amendment 25-39, Effective February 10, 1977. 228

325. Amendment 25-46, Effective February 11, 1978. 236

326. Amendment 25-55, Effective April 26, 1982. 245

327. Amendment 25-67, Effective July 24, 1989. 254

328. Amendment 25-72, Effective August 20, 1990. 263

329. Amendment 25-88, Effective December 9, 1996. 270

330. Amendment 25-94, Effective March 25, 1998. 277 331 - 350. [RESERVED] SECTION 25.809 EMERGENCY EXIT ARRANGEMENT

351. Regulation in Effect at Adoption of Part 25. 285

352. Amendment 25-1, Effective June 7, 1965. 285

353. Amendment 25-9, Effective June 30, 1966. 290

354. Amendment 25-15, Effective October 24, 1967. 292

355. Amendment 25-32, Effective, May 1, 1972. 296

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vii

356. Amendment 25-34, Effective December 31, 1972. 301

357. Amendment 25-46, Effective December 1, 1978. 306

358. Amendment 25-47, Effective December 24, 1979. 312

359. Amendment 25-72, Effective August 20, 1990. 318 360 - 370. [RESERVED] SECTION 25.810 EMERGENCY EGRESS ASSIST MEANS

**AND ESCAPE ROUTES**

371. Section 25.810 Did Not Exist Prior to Amendment 25-72. 321

372. Amendment 25-72, Effective August 20, 1990. 321

373. Amendment 25-88, Effective December 9, 1996. 326 374 - 380. [RESERVED] SECTION 25.811 EMERGENCY EXIT MARKING

381. Regulation in Effect at Adoption of Part 25. 333

382. Amendment 25-1, Effective June 7, 1965. 334

383. Amendment 25-15, Effective October 24, 1967. 339

384. Amendment 25-32, Effective May 1, 1972. 344

385. Amendment 25-46, Effective December 1, 1978. 349

386. Amendment 25-79, Effective September 27, 1993. 355

387. Amendment 25-88, Effective December 9, 1996. 360 388 - 390. [RESERVED] SECTION 25.812 EMERGENCY LIGHTING

391. Section 25.812 Did Not Exist Prior to Amendment 25-15. 365

392. Amendment 25-15, Effective October 24, 1967. 365

393.

Amendment 25-28, Effective September 25, 1971. 369

394. Amendment 25-32, Effective May 1, 1972. 373

395. Amendment 25-46, Effective December 1, 1978. 378

396. Amendment 25-58, Effective November 26, 1984. 383

397. Amendment 25-88, Effective December 9, 1996. 389

398 - 410. [RESERVED] SECTION 25.813 EMERGENCY EXIT ACCESS

411. Regulation in Effect at Adoption of Part 25. 397

412. Amendment 25-1, Effective June 7, 1965. 403

413. Amendment 25-15, Effective October 24, 1967. 409

414. Amendment 25-17, Effective June 20, 1968. 417

415. Amendment 25-32, Effective May 1, 1972. 424

416. Amendment 25-46, Effective December 1, 1978. 432

417. Amendment 25-72, Effective August 20, 1990. 440

418. Amendment 25-76, Effective June 3, 1992. 450

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viii

419. Amendment 25-88, Effective December 9, 1996. 461 420 - 440. [RESERVED] SECTION 25.815 WIDTH OF MAIN AISLE

441. Regulation in Effect at Adoption of Part 25. 473

442. Amendment 25-15, Effective October 24, 1967. 474

443. Amendment 25-38, Effective February 1, 1977. 476 444 - 460. [RESERVED] SECTION 25.817 MAXIMUM NUMBER OF SEATS ABREAST

461. Section 25.817 Did Not Exist Prior to Amendment 25-15. 479

462. Amendment 25-15, Effective October 24, 1967. 479 463 - 480. [RESERVED] SECTION 25.819 LOWER DECK SERVICE COMPARTMENTS (INCLUDING GALLEYS)

481. Section 25.819 Did Not Exist Prior to Amendment 25-53. 481

482. Amendment 25-53, Effective August 31, 1980. 481

483. Amendment 25-110, Effective July 21, 2003. 483 484 - 600. [RESERVED] SECTION 25.851 FIRE EXTINGUISHERS

601. Regulation in Effect at Adoption of Part 25. 487

602. Amendment 25-54, Effective October 14, 1980. 490

603. Amendment 25-72, Effective August 20, 1990. 493

604. Amendment 25-74, Effective May 16, 1991. 497 605 - 620. [RESERVED] SECTION 25.853 COMPARTMENT INTERIORS

621. Regulation in Effect at Adoption of Part 25. 503

622. Amendment 25-15, Effective October 24, 1967. 508

623. Amendment 25-17, Ef fective June 20, 1968. 511

624. Amendment 25-23, Effective May 8, 1970. 515

625. Amendment 25-32, Effective May 1, 1972. 519

626. Amendment 25-51, Effective March 6, 1980. 523

627. Amendment 25-59, Effective November 26, 1984. 528

628. Amendment 25-60, Effective June 16, 1986. 532

629. Amendment 25-61, Effective August 20, 1986. 537

630. Amendment 25-66, Effective September 26, 1988. 542

631. Amendment 25-72, Effective August 20, 1990. 548

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ix

632. Amendment 25-83, Effective March 6, 1995. 552 633 - 640. [RESERVED] SECTION 25.854 LAVATORY FIRE PROTECTION

641. Section 25.854 Did Not Exist Prior to Amendment 25-74. 557

642. Amendment 25-74, Effective May 16, 1991. 557 643 - 650. [RESERVED] SECTION 25.855 CARGO AND BAGGAGE

**COMPARTMENTS**

651. Regulation in Effect at Adoption of Part 25. 559

652. Amendment 25-15, Effective October 24, 1967. 560

653. Amendment 25-32, Effective May 1, 1972. 561

654. Amendment 25-60, Effective June 16, 1986 563

655. Amendment 25-72, Effective August 20, 1990. 565

656. Amendment 25-93, Effective March 19, 1998. 567 657 - 660. [RESERVED] SECTION 25.856 THERMAL/ACOUSTIC INSULATION

**MATERIALS**

661. Section 25.856 Did Not Exist Prior to Amendment 25-111. 571

662. Amendment 25-111, Effective September 2, 2003. 571 663 - 670. [RESERVED] SECTION 25.857 CARGO COMPARTMENT

**CLASSIFICATION**

671. Regulation in Effect at Adoption of Part 25. 573

672. Amendment 25-32, Effective May 1, 1972. 576

673. Amendment 25-60, Effective June 16, 1986. 580

674. Amendment 25-93, Effective March 19, 1998. 583 675 - 730. [RESERVED] SECTION 25.869 FIRE PROTECTION: SYSTEMS

731. S ection 25.869 Did Not Exist Prior to Amendment 25-72. 587

732. Amendment 25-72, Effective July 20, 1990. 587 733 - 750. [RESERVED] SECTION 25.1307 MISCELLANEOUS

751. Regulation in Effect at Adoption of Part 25. 589

752. Amendment 25-23, Effective May 8, 1970. 589

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x

753. Amendment 25-46, Effective December 1, 1978. 590

754. Amendment 25-54, Effective October 14, 1980. 591

755. Amendment 25-72, Effective August 20, 1990. 592 756 - 780. [RESERVED] SECTION 25.1359 ELECTRICAL SYSTEM FIRE AND SMOKE

**PROTECTION**

781. Section 25.1359(d) Did Not Exist Prior to Amendment 25-32. 595

782. Amendment 25-32, Effective May 1, 1972. 595

783. Removed at Amendment 25-72, Effective August 20, 1990. 595 784 - 800. [RESERVED] SECTION 25.1411 SAFETY EQUIPMENT—GENERAL

801. Regulation in Effect at Adoption of Part 25. 597

802. Amendment 25-32, Effective May 1, 1972. 599

803. Amendment 25-46, Effective December 1, 1978. 601

804. Amendment 25-53, Effective August 31, 1980. 603

805. Amendment 25-70, Effective November 27, 1989. 606

806. Amendment 25-79, Effective September 27, 1993. 608 807 - 820. [RESERVED] SECTION 25.1413 SAFETY BELTS

821. Regulation in Effect at Adoption of Part 25. 613

822. Amendment 25-44, Effective December 4, 1978. 613

823. Amendment 25-51, Effective March 8, 1980. 614

824. Removed at Amendment 25-72, Effective July 20, 1990. 614 825 - 840. [RESERVED] SECTION 25.1415 DITCHING EQUIPMENT

841. Regulation in Effect at Adoption of Part 25. 615

842. Amendment 25-29, Effective October 21, 1971. 617

843. Amendment 25-52, Effective September 9, 1980. 619

844. Amendment 25-72, Effective August 20, 1990. 622

845.

Amendment 25-82, Effective June 21, 1994. 624 846 - 880. [RESERVED] SECTION 25.1421 MEGAPHONES

881. Section 25.1421 Did Not Exist Prior to Amendment 25-41. 627

882. Amendment 25-41, Effective September 1, 1977. 627 883 - 900. [RESERVED]

### Page 13

xi SECTION 25.1423 PUBLIC ADDRESS SYSTEMS

901. Section 25.1423 Did Not Exist Prior to Amendment 25-70. 629

902. Amendment 25-70, Effective November 27, 1989. 629

903. Amendment 25-79, Effective September 27, 1993. 629 904 – 920. [RESERVED] SECTION 25.1439(a) PROTECTIVE BREATHING

**EQUIPMENT**

921. Regulation in Effect at Adoption of Part 25. 631

922. Amendment 25-38, Effective February 1, 1977.. 631 923 - 970. [RESERVED] SECTION 25.1447 EQUIPMENT STANDARDS FOR OXYGEN

**DISPENSING UNITS**

971. Regulation in Effect at Adoption of Part 25. 633

972. Amendment 25-41, Effective September 1, 1977. 635

973. Amendment 25-87, Effective July 5, 1996. 637 974 - 1010. [RESERVED] SECTION 25.1451 FIRE PROTECTION FOR OXYGEN

EQUIPMENT 1011. Regulation in Effect at Adoption of Part 25. 641 1012. Removed at Amendment 25-72, Effective August 20, 1990. 641 1013 - 1040. [RESERVED] SECTION 25.1541 MARKINGS AND PLACARDS—GENERAL 1041. Regulation in Effect at Adoption of Part 25. 643 1042 - 1060. [RESERVED] SECTION 25.1557(a), (c), and (d) MISCELLANEOUS

MARKINGS AND PLACARDS 1061. Regulation in Effect at Adoption of Part 25. 645 1062. Amendment 25-32, Effective May 1, 1972. 645 1063. Amendment 25-38, Effective February 1, 1977. 646 1064. Amendment 25-72, Effective August 20, 1990. 646 1065 - 1100. [RESERVED]

### Page 14

xii SECTION 25.1561 SAFETY EQUIPMENT 1101. Regulation in Effect at Adoption of Part 25. 647 1102. Amendment 25-46, Effective December 1, 1978. 647 1103 - 1150. [RESERVED] APPENDIX F TO PART 25 ACCEPTABLE PROCEDURES

FOR FLAMMABILITY TESTING FOR COMPLIANCE WITH PART 25 FLAMMABILITY REQUIREMENTS 1151. Appendix F Did Not Exist Prior to Amendment 25-15. 649 1152. Appendix F, Amendment 25-15, Effective October 24, 1967. 649 1153. Appendix F, Amendment 25-32, Effective May 1, 1972. 650 1154. Appendix F, Amendment 25-55, Effective April 26, 1982. 653 1155. [Part I] Amendment 25-59, Effective November 26, 1984. 655 1156. Part I Amendment 25-72, Effective August 20, 1990. 658 1157. Part I Amendment 25-111, Effective September 2, 2003. 662 1158 - 1161. [RESERVED] 1162. Appendix F, Part II, Did Not Exist Prior to Amendment 25-59. 667 1163. Part II Amendment 25-59, Effective November 26, 1984. 667 1164. Part II Amendment 25-72, Effective August 20, 1990. 677 1165. Part II Amendment 25-94, Effective March 25, 1998. 685 1166 - 1170. [RESERVED] 1171. Appendix F, Part III, Did Not Exist Prior to Amendment 25-60. 693 1172. Amendment 25-60, Effective June 16, 1986. 693 1173 - 1177. [RESERVED] 1178. Appendix F, Part IV, Did Not Exist Prior to Amendment 25-61. 701 1179. Part IV Amendment 25-61, Effective August 20, 1986. 701 1180. Part IV Amendment 25-66, Effective September 26, 1988. 715 1181 - 1185. [RESERVED] 1186. Appendix F, Part V, Did Not Exist Prior to Amendment 25-66. 727 1187. Part V Amendment 25-66, Effective September 26, 1988. 727

1188 - 1192. [RESERVED] 1193. Appendix F, Part VI, Did Not Exist Prior to Amendment 25-111. 729 1194. Amendment 25-111, Effective September 2, 2003. 729 1195 - 1200. [RESERVED]

### Page 15

xiii 1201. Appendix F, Part VII, Did Not Exist Prior to Amendment 25-111. 743 1202. Appendix F, Amendment 25-111, Effective September 2, 2003. 743 1203 - 1207. [RESERVED] APPENDIX J TO PART 25—EMERGENCY EVACUATION 1208. Appendix J Did Not Exist at Prior to Amendment 25-72. 759 1209. Appendix J, Amendment 25-72, Effective August 20, 1990. 759 1210. Appendix J, Amendment 25-79, Effective September 27, 1993. 761 1211 - 1300. [RESERVED] Appendix 1. CROSS REFERENCE FOR PART 25 AT AMENDMENT 25-0 765 AND CAM 4b Appendix 2. SYMBOLIC REGULATORY MESSAGES 767 Appendix 3. CRASHWORTHINESS ADVISORY CIRCULARS 773 Appendix 4. TEST PROCEDURES FOR EVALUATING NONSTANDARD 777

EXITS FOR TRANSPORT CATEGORY AIRPLANES Appendix 5. CRASHWORTHINESS TECHNICAL STANDARD ORDERS 781 Appendix 6. INTERIOR COMPLIANCE CHECKLIST- EXAMPLE 783 Appendix 7. AMENDMENT BY AMENDMENT HISTORY OF 793

CRASHWORTHINESS REQUIREMENTS Appendix 8. FIRE CONTAINMENT TEST METHODS 805 Appendix 9. ACRONYMS 813 Appendix 10. CROSS REFERENCE FOR PRE-AMENDMENT 25-72 AND 815 POST AMENDMENT 25-72 Appendix 11. FAA MEMORANDUM, 01-115-11, ORIGINAL RELEASE: 819 DAT ED NOVEMBER 6, 2001, LATEST REVISION, SUBJECT:

**CERTIFICATION OF STRENGTHENED FLIGHTDECK**

DOORS ON TRANSPORT CATEGORY AIRPLANES Appendix 12. ESTABLISHING THE MAXIMUM PASSENGER SEATING 841

**CAPACITY FOR AN AIRPLANE MODEL**

### Page 16

xiv Appendix 13. FAA POLICY MEMO ANM-03-115-31, “POLICY 845

**STATEMENT ON CONDUCTING COMPONENT LEVEL**

TESTS TO DEMONSTRATE COMPLIANCE WITH §§ 25.785(B) AND (D)” DATED MAY 9, 2005 Appendix 14. FAA POLICY MEMO ANM-115-05-001, “POLICY 867 STATEMENT ON THE INSTALLATION OF “NO STOWAGE”

**PLACARDS ON SURFACES NOT DESIGNED OR INTENDED**

TO BE USED FOR STOWAGE Appendix 15. FIGURES SHOWING REQUIRED AISLES, CROSS AISLES, 873

**AND PASSAGEWAYS FOR TYPE A AND B EXITS**

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**1 SECTION 25.561 EMERGENCY LANDING CONDITIONS GENERAL**

**11. REGULATION IN EFFECT AT ADOPTION OF PART 25.**

a. Regulation.

(a) The airplane, although it may be damaged in emergency landing conditions on land or water, must be designed as prescribed in this section to protect each occupant under those conditions.

(b) The structure must be designed to give each occupant every reasonable chance of escaping serious injury in a minor crash landing when-

(1) Proper use is made of seats, belts, and all other safety design provisions;

(2) The wheels are retracted (where applicable); and

(3) The occupant experiences the following ultimate inertia forces relative to the surrounding structure:

(i) Upward-2.0 g.

(ii) Forward-9.0 g.

(iii) Sideward-1.5 g.

(iv) Downward-4.5 g, or any lesser force that will not be exceeded when the airplane absorbs the landing loads resulting from impact with an ultimate descent velocity of five f.p.s. at design landing weight.

(c) The supporting structure must be designed to restrain, under all loads up to those specified in paragraph (b) (3) of this section, each item of mass that could injure an occupant if it came loose in a minor crash landing.

b. Guidance. Paragraph (b). When testing a seat to demonstrate compliance with the static requirements of § 25.561, the testing should be conducted with an occupant center of gravity (CG) location as defined in NAS 809 (referenced in Technical Standard Order (TSO) C39) and AS8049 (referenced in the current version of TSO-C127). This CG location should be utilized in any airplane interface load analysis conducted. (Amendment 25-0)

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12. AMENDMENT 25-23, Effective May 8, 1970.

a. Regulation.

(a) The airplane, although it may be damaged in emergency landing conditions on land or water, must be designed as prescribed in this section to protect each occupant under those conditions.

(b) The structure must be designed to give each occupant every reasonable chance of escaping serious injury in a minor crash landing when—

(1) Proper use is made of seats, belts, and all other safety design provisions;

(2) The wheels are retracted (where applicable); and

(3) The occupant experiences the following ultimate inertia forces [acting separately] relative to the surrounding structure:

(i) Upward-2.0g.

(ii) Forward-9.0g.

(iii) Sideward-1.5g .

(iv) Downward-4.5g, or any lesser force that will not be exceeded when the airplane absorbs the landing loads resulting from impact with an ultimate descent velocity of five f.p.s. at design landing weight.

(c) The supporting structure must be designed to restrain, under all loads up to those specified in paragraph (b)(3) of this section, each item of mass that could injure an occupant if it came loose in a minor crash landing.

b. Guidance. Paragraph (b). When testing a seat to demonstrate compliance with the static requirements of § 25.561, the testing should be conducted with an occupant center of gravity (CG) location as defined in NAS 809 (referenced in Technical Standard Order (TSO) C39) and AS8049 (referenced in the current version of TSO-C127). This CG location should be utilized in any airplane interface load analysis conducted. (Amendment 25-0)

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13. AMENDMENT 25-64, Effective June 16, 1988.

a. Regulation.

(a) The airplane, although it may be damaged in emergency landing conditions on land or water, must be designed as prescribed in this section to protect each occupant under those conditions.

(b) The structure must be designed to give each occupant every reasonable change of escaping serious injury in a minor crash landing when—

(1) Proper use is made of seats, belts, and all other safety design provisions;

(2) The wheels are retracted (where applicable); and

(3) The occupant experiences the following ultimate inertia forces acting separately relative to the surrounding structure:

(i) [Upward, 3.0g.]

(ii) Forward, 9.0g.

(iii) [Sideward, 3.0g on the airframe; and 4.0g on the seats and their attachments.

(iv) Downward, 6.0g.

(v) Rearward, 1.5g]

(c) The supporting structure must be designed to restrain, under all loads up to those specified in paragraph (b)(3) of this section, each item of mass that could injure an occupant if it came loose in a minor crash landing.

[(d) Seats and items of mass (and their supporting structure) must not deform under any loads up to those specified in paragraph (b)(3) of this section in any manner that would impede subsequent rapid evacuation of occupants.]

b. Guidance.

(1) Paragraph (b). When testing a seat to demonstrate compliance with the static requirements of § 25.561, the testing should be conducted with an occupant center of gravity (CG) location as defined in NAS 809 (referenced in Technical Standard Order (TSO) C39) and AS8049 (referenced in the current version of TSO-C127). This CG location should be utilized in any airplane interface load analysis conducted. (Amendment 25-0)

(2) Paragraph (d). The permanent deformations of items of mass, such as galleys and closets, located near exits should not interfere with the opening of those exits. Also, shared

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4 loading (loads imposed by the deformation of one furnishing onto an adjacent furnishing) between adjacent items of mass should be considered when determining maximum deformations.

Refer to AC 25.562-1B “Dynamic Evaluation of Seat Restraint Systems & Occupant Protection on Transport Airplanes,” dated 1/19/96, Appendix 2 for policy concerning seat deformations for both §§ 25.561(d) and 25.562(c)(8). For § 25.561(d) only the forward, rearward, and sideward deformations are applicable. Deformations and possible load sharing between articles need only be considered for a common load case (e.g., 9g to 9g & 16g to 16g). The dynamic deflections of seats in particular do not have to be considered in conjunction with the static deflections of other articles when assessing possible load sharing. That is, when a seat substantiated under § 25.562 has interaction with another article substantiated under § 25.561, the assessment of load sharing is done using the § 25.561 deflections/reactions for both articles. (Amendment 25-64)

14. AMENDMENT 25-91, Effective July 29, 1997.

a. Regulation.

(a) The airplane, although it may be damaged in emergency landing conditions on land or water, must be designed as prescribed in this section to protect each occupant under those conditions.

(b) The structure must be designed to give each occupant every reasonable chance of escaping serious injury in a minor crash landing when-

(1) Proper use is made of seats, belts, and all other safety design provisions;

(2) The wheels are retracted (where applicable); and

(3) The occupant experiences the following ultimate inertia forces relative to the surrounding structure:

(i) Upward, 3.0g.

(ii) Forward, 9.0g.

(iii) Sideward, 3.0g on the airframe; and 4.0g on the seats and their attachments.

(iv) Downward, 6.0g.

(v) Rearward, 1.5g.

[(c) For equipment, cargo in the passenger compartments and any other large masses, the following apply:

(1) Except as provided in paragraph (c)(2) of this section, these items must be positioned so that if they break loose, they will be unlikely to:

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(i) Cause direct injury to occupants;

(ii) Penetrate fuel tanks or lines or cause fire or explosion hazard by damage to adjacent systems; or

(iii) Nullify any of the escape facilities provided for use after an emergency landing.

(2) When such positioning is not practical (e.g. fuselage mounted engines or auxiliary power units) each such item of mass shall be restrained under all loads up to those specified in paragraph (b)(3) of this section. The local attachments for these items should be designed to withstand 1.33 times the specified loads if these items are subject to severe wear and tear through frequent removal (e.g. quick change interior items).]

(d) Seats and items of mass (and their supporting structure) must not deform under any loads up to those specified in paragraph (b)(3) of this section in any manner that would impede subsequent rapid evacuation of occupants.

b. Guidance.

(1) Paragraph (b). When testing a seat to demonstrate compliance with the static requirements of § 25.561, the testing should be conducted with an occupant center of gravity (CG) location as defined in NAS 809 (referenced in Technical Standard Order (TSO) C39) and AS8049 (referenced in the current version of TSO-C127). This CG location should be utilized in any airplane interface load analysis conducted. (Amendment 25-0)

(2) Paragraph (d). The permanent deformations of items of mass, such as galleys and closets, located near exits should not interfere with the opening of those exits. Also, shared loading (loads imposed by the deformation of one furnishing onto an adjacent furnishing) between adjacent items of mass should be considered when determining maximum deformations.

Refer to AC 25.562-1B dated 1/10/2006, Appendix 2 for policy concerning seat deformations for both §§ 25.561(d) and 25.562(c)(8). For § 25.561(d) only the forward, rearward, and sideward deformations are applicable. Deformations and possible load sharing between articles need only be considered for a common load case (e.g., 9g to 9g & 16g to 16g) . The dynamic deflections of seats in particular do not have to be considered in conjunction with the static deflections of other articles when assessing possible load sharing. That is, when a seat substantiated under § 25.562 has interaction with another article substantiated under § 25.561, the assessment of load sharing is done using the § 25.561 deflections/reactions for both articles. (Amendment 25-64) 15 – 20. [RESERVED]

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**7 SECTION 25.562 EMERGENCY LANDING DYNAMIC CONDITIONS**

21. Section 25.562 Did Not Exist Prior to Amendment 25-64.

22. AMENDMENT 25-64, Effective June 16, 1988.

a. Regulation.

(a) The seat and restraint system in the airplane must be designed as prescribed in this section to protect each occupant during an emergency landing condition when-

(1) Proper use is made of seats, safety belts, and shoulder harnesses provided for in the design; and

(2) The occupant is exposed to loads resulting from the conditions prescribed in this section.

(b) Each seat type design approved for crew or passenger occupancy during takeoff and landing must successfully complete dynamic tests or be demonstrated by rational analysis based on dynamic tests of a similar type seat, in accordance with each of the following emergency landing conditions. The tests must be conducted with an occupant simulated by a 170-pound anthropomorphic test dummy, as defined by 49 CFR Part 572, Subpart B, or its equivalent, sitting in the normal upright position.

(1) A change In downward vertical velocity (∆V) of not less than 35 feet per second, with the airplane's longitudinal axis canted downward 30 degrees with respect to the horizontal plane and with the wings level. Peak floor deceleration must occur in not more than 0.08 seconds after impact and must reach a minimum of 14g.

(2) A change in forward longitudinal velocity (∆V) of not less than 44 feet per second, with the airplane's longitudinal axis horizontal and yawed 10 degrees either right or left, whichever would cause the greatest likelihood of the upper torso restraint system (where installed) moving off the occupant's shoulder, and with the wings level. Peak floor deceleration must occur in not more than 0.09 seconds after impact and must reach a minimum of 16g. Where floor rails or floor fittings are used to attach the seating devices to the test fixture, the rails or fittings must be misaligned with respect to the adjacent set of rails or fittings by at least 10 degrees vertically

(i.e., out of Parallel) with one rolled 10 degrees.

(c) The following performance measures must not be exceeded during the dynamic tests conducted in accordance with paragraph (b) of this section:

(1) Where upper torso straps are used for crewmembers, tension loads in individual straps must not exceed 1,750 pounds. If dual straps are used for restraining the upper torso, the total strap tension loads must not exceed 2,000 pounds.

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(2) The maximum compressive load measured between the pelvis and the lumbar column of the anthropomorphic dummy must not exceed 1,500 pounds.

(3) The upper torso restraint straps (where installed) must remain on the occupant's shoulder during the impact.

(4) The lap safety belt must remain on the occupant's pelvis during the impact.

(5) Each occupant must be protected from serious head injury under the conditions prescribed in paragraph (b) of this section. Where head contact with seats or other structure can occur, protection must be provided so that the head impact does not exceed a Head Injury Criterion (HIC) of 1,000 units. The level of HIC is defined by the equation:

Where:

t1 is the initial integration time, t2 is the final integration time, and a(t) is the total acceleration vs. time-curve for the head strike, and where

(t) is in seconds, and (a) is in units of gravity (g).

(6) Where leg injuries may result from contact with seats or other structure, protection must be provided to prevent axially compressive loads exceeding 2,250 pounds in each femur.

(7) The seat must remain attached at all points of attachment, although the structure may have yielded.

(8) Seats must not yield under the tests specified in paragraphs (b)(1) and (b)(2) of this section to the extent they would impede rapid evacuation of the airplane occupants.

b. Guidance.

(1) Refer to AC 25.562-1B, “Dynamic Evaluation of Seat Restraint Systems & Occupant Protection on Transport Airplanes,” dated 1/10/2006. (Amendment 25-64) HIC = (t - t ) [ 1(t - t ) tt a(t ) dt ][ 2 1 2 1 12 2.5∫ ]max

### Page 25

(2) Paragraph (c)(5). The FAA issued policy memorandum ANM-03-115-28, dated October 2, 2003, and titled “Policy Statement on Use of Surrogate Parts When Evaluating Seatbacks and Seatback Mounted Accessories for Compliance with §§ 25.562(c)(5) and

25.785(b) and (d). This policy may be used with any test method used to demonstrate compliance with blunt force trauma for items mounted on the seatback. The new policy may be used for demonstrating compliance with § 25.562(c)(5), Amendment 25-64, and is provided below. (Amendment 25-64)

(i) The FAA has determined that it is acceptable to use a surrogate test article made of 6061-T4 aluminum which meets the criteria below in lieu of an accessory for demonstrating compliance with §§ 25.562(c)(5) and 25.785(b) and (d) for blunt trauma assessments. An exception to the use of the surrogate test article occurs when the accessory is more rigid (deflects less and absorbs less energy during impact) than the plate defined in this memorandum. In that case, the accessory should be used in the test(s) and not a surrogate test article. The following criteria are applicable when using a surrogate test article during blunt trauma testing in accordance with §§ 25.562(c)(5) and 25.785(b) and (d): (Amendment 25-64) (A) The surrogate part should be fabricated from 6061-T4 aluminum and have a minimum thickness of 0.238-inch (i.e., 0.25-inch minus a 0.012-inch manufacturing tolerance) at all locations. The length and width of the surrogate part should equal, within tolerances, the length and width of the actual part, respectively. (Amendment 25-64) (B) The exposed surface of the surrogate part that will be impacted should be flat. That is, it is not required to have the contour of the accessory’s exposed surface represented by the surrogate part. Note that this is based on typical accessory installations, which are essentially mounted flush with the seatback and have a generally homogeneous contact area.

Small variations in the surface due to the contour of plastic parts may be ignored. Designs that differ from this (e.g., a design with an exposed structural protrusion) might require the exposed surface of the actual part to be represented in order to adequately assess head injury potential.

(Amendment 25-64) (C) The weight of the surrogate part, and additional ballast if needed, should be ±10 percent of the weight of the actual part. (Amendment 25-64) (D) The surrogate part should be located on the seatback in the same place

(i.e., within manufacturing tolerances for mounting the actual part) where the actual part would be located in terms of the x and y coordinates in Figure 22-1. The surrogate part should be located such that the surface, which will be contacted during the test, is at the same location (i.e., within manufacturing tolerances for mounting the actual part) where the actual part would be in terms of the z coordinate (refer to figure 22-1). (Amendment 25-64) (E) The surrogate part should be attached to the seat by the final production hardware or a conservative representation of the final production hardware. For substantiating blunt trauma requirements, a conservative representation of the attachment hardware would be at least as rigid as the actual hardware. The surrogate part should be mounted so that it would not move farther or faster, with respect to the seatback, than the actual part during the test. Note that

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10 a conservative representation of the attachment hardware for determining HIC may not adequately represent the attachment hardware for substantiating it to § 25.562 loads. However, if the attachment hardware is adequately represented for substantiating it to § 25.562 loads, the test using a surrogate part may also be used to demonstrate that the attachment hardware will retain the actual accessory under § 25.562 loads. (Amendment 25-64) (F) If the surrogate part cracks during a test, the test results are invalid.

(Amendment 25-64) (G) A surrogate part made of a material and thickness other than 6061-T4 aluminum in a nominal thickness of 0.25-inch may be used if an FAA Aircraft Certification Office finds that it is at least as rigid (i.e., it deflects less and absorbs less energy during the test).

Surrogate test articles which are less rigid than the aluminum surrogate part defined above are not addressed in this AC. If an applicant desires to use a surrogate part which is less rigid, its use should be approved through the issue paper process (or equivalent) or by an FAA policy memorandum. Testing may be required to determine the acceptability of these less rigid surrogate parts. (Amendment 25-64)

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FIGURE 22-1 SURROGATE PART INSTALLED ON SEATBACK Surrogate part installed on the back side of the seatback in lieu of the actual accessory.

The x and y axes are in the plane of the backside of the seatback 23 - 40. [RESERVED] 11

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### Page 29

**13 SECTION 25.772 PILOT COMPARTMENT DOORS**

41. Section 25.772 Did Not Exist Prior to Amendment 25-33.

42. AMENDMENT 25-33, Effective October 21, 1972.

a. Regulation.

(a) Except as provided in paragraph (b) of this section, if a lockable door is installed between the pilot compartment and the passenger compartment to comply with § 121.313(f) of this chapter, the emergency exit configuration of the airplane must be designed so that neither crewmembers nor passengers need use that door in order to reach the emergency exits provided for them.

(b) The provisions of paragraph (a) of this section do not apply to an airplane that-

(l) Has a maximum passenger seating configuration of 20 seats or less; or

(2) Is excepted from the equipment requirements of § 121.313(f) under the provisions of § 121.583(a) of this chapter.

b. Guidance. There is no guidance for this regulation.

43. AMENDMENT 25-47, Effective December 24, 1979.

a. Regulation.

(a) Except as provided in paragraph (b) of this section, if a lockable door is installed between the pilot compartment and the passenger compartment to comply with § 121.313(f) of this chapter, the emergency exit configuration of the airplane must be designed so that neither crewmembers nor passengers need use that door in order to reach the emergency exits provided for them. [However, for passenger configuration, means must be provided to enable flight crewmembers to directly enter the passenger compartment from the pilot compartment if the cockpit door becomes jammed.]

(b) The provisions of paragraph (a) of this section do not apply to an airplane that-

(1) Has a maximum passenger seating configuration of 20 seats or less; or

(2) Is excepted from the equipment requirements of § 121.313(f) under the provisions of § 121.583(a) of this chapter.

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b. Guidance.

(1) Paragraph (a). Compliance may be shown by either analysis or demonstration.

(Amendment 25-47)

(2) Paragraph (a). Acceptance of frangible doors. The following test procedure is acceptable to demonstrate that the door between the pilot compartment and the passenger compartment will not block the flight crewmembers' escape in the event the door is jammed. An acceptable means of showing compliance is by demonstrating that the door is frangible and the flightcrew participants can rapidly egress from the pilot compartment without assistance.

(Amendment 25-47)

(i) The test should be conducted in an airplane, or a mockup if the mockup conforms to the production airplane's interior configuration. If a mockup is used, it should include the observer's seat(s), if they are part of the type design, and the bulkhead and door to be tested. The door should be blocked to simulate possible jamming from the top, bottom, and sides (closing and locking alone may not be adequate to simulate all possible jamming). If the fragments from the broken door could cause an obstruction to the escape routes for passenger emergency egress, and if an emergency evacuation demonstration is required by airworthiness regulations or operating rules, consideration should be given to include the passengers in the test.

For emergency evacuation demonstrations with passengers, refer to § 25.803(c), Amendment 25-

15. (Amendment 25-47)

(ii) Two participants representing a pilot in the left crew seat and a copilot in the right crew seat should be used for the test. They should be persons with no special escape abilities. The crewmembers should be a female approximately 60-inches tall and weighing no more than 102 lbs and a male approximately 74-inches tall and weighing no less than 210 lbs.

The foregoing statures and weights represent the 5th percentile female to 95th percentile male occupants respectively. The female participant will be instructed to break the door and be the first person to egress without assistance from the male participant. Instructions for enhancing the egress should be limited to those instructions that will be provided in the FAA-approved Airplane Flight Manual (AFM) or on the related placards. (Amendment 25-47)

(iii) The test should be conducted in night conditions. If conducted in a hangar during the day, the hangar should be draped and taped so that all sunlight is prevented from entering the hangar. Similar conditions should exist if conducted at night either in or out of a hangar. Lighting may be allowed at ground level to aid in leaving the area near the airplane providing the lighting is kept low and shielded so it does not aid evacuating the airplane. Use of emergency lighting is acceptable. (Amendment 25-47)

(iv) Personnel participating should be informed of the purpose of the demonstration and of the safety precautions. Safety of participants is the responsibility of the applicant, and should be considered to prevent injuries to the participants without compromising the test results.

Participants may wear protective gear such as crash helmets, but the protective gear, tools, or any other device should not be used to break through the door. (Amendment 25-47)

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44. AMENDMENT 25-72, Effective August 20, 1990.

a. Regulation.

[For an airplane that has a maximum passenger seating configuration of more than 20 seats and that has a lockable door installed between the pilot compartment and the passenger compartment:

(a) The emergency exit configuration must be designed so that neither crewmembers nor passengers need use that door in order to reach the emergency exits provided for them; and

(b) Means must be provided to enable flight crewmembers to directly enter the passenger compartment from the pilot compartment if the cockpit door becomes jammed.]

b. Guidance.

(1) Paragraph (b). Compliance may be shown by either analysis or demonstration.

(Amendment 25-47)

(2) Paragraph (b). Acceptance of frangible doors. The following test procedure is acceptable to demonstrate that the door between the pilot compartment and the passenger compartment will not block the flight crewmembers' escape in the event the door is jammed. An acceptable means of showing compliance is by demonstrating that the door is frangible and the flightcrew participants can rapidly egress from the pilot compartment without assistance.

(Amendment 25-47)

(i) The test should be conducted in an airplane, or a mockup if the mockup conforms to the production airplane's interior configuration. If a mockup is used, it should include the observer's seat(s), if they are part of the type design, and the bulkhead and door to be tested. The door should be blocked to simulate possible jamming from the top, bottom, and sides (closing and locking alone may not be adequate to simulate all possible jamming). If the fragments from the broken door could cause an obstruction to the escape routes for passenger emergency egress, and if an emergency evacuation demonstration is required by airworthiness regulations or operating rules, consideration should be given to include the passengers in the test.

For emergency evacuation demonstrations with passengers, refer to § 25.803(c), Amendment 25-

15. (Amendment 25-47)

(ii) Two participants representing a pilot in the left crew seat and a copilot in the right crew seat should be used for the test. They should be persons with no special escape abilities. The crewmembers should be a female approximately 60-inches tall and weighing no more than 102 lbs and a male approximately 74-inches tall and weighing no less than 210 lbs.

The foregoing statures and weights represent the 5th percentile female to 95th percentile male occupants respectively. The female participant will be instructed to break the door and be the first person to egress without assistance from the male participant. Instructions for enhancing the

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16 egress should be limited to those instructions that will be provided in the FAA-approved Airplane Flight Manual (AFM) or on the related placards. (Amendment 25-47)

(iii) The test should be conducted in night conditions. If conducted in a hangar during the day, the hangar should be draped and taped so that all sunlight is prevented from entering the hangar. Similar conditions should exist if conducted at night either in or out of a hangar. Lighting may be allowed at ground level to aid in leaving the area near the airplane providing the lighting is kept low and shielded so it does not aid evacuating the airplane. Use of emergency lighting is acceptable. (Amendment 25-47)

(iv) Personnel participating should be informed of the purpose of the demonstration and of the safety precautions. Safety of participants is the responsibility of the applicant, and should be considered to prevent injuries to the participants without compromising the test results.

Participants may wear protective gear such as crash helmets, but the protective gear, tools, or any other device should not be used to break through the door. (Amendment 25-47)

45. AMENDMENT 25-106, Effective January 15, 2002.

a. Regulation.

For an airplane that has a [lockable door installed between the pilot compartment and the passenger compartment:

(a) For airplanes with a maximum passenger seating configuration of more than 20 seats, the emergency exit configuration must be designed so that neither crewmembers nor passengers require use of the flightdeck door in order to reach the emergency exits provided for them;]

(b) Means must be provided to enable flight crewmembers to directly enter the passenger compartment from the pilot compartment if the cockpit door becomes jammed.

[(c) There must be an emergency means to enable a flight attendant to enter the pilot compartment in the event that the flightcrew becomes incapacitated.]

b. Guidance.

(1) Paragraph (b). Compliance may be shown by either analysis or demonstration.

(Amendment 25-47)

(2) Paragraph (b). Acceptance of frangible doors. The following test procedure is acceptable to demonstrate that the door between the pilot compartment and the passenger compartment will not block the flight crewmembers' escape in the event the door is jammed. An acceptable means of showing compliance is by demonstrating that the door is frangible and the

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17 flightcrew participants can rapidly egress from the pilot compartment without assistance.

(Amendment 25-47)

(i) The test should be conducted in an airplane, or a mockup if the mockup conforms to the production airplane's interior configuration. If a mockup is used, it should include the observer's seat(s), if they are part of the type design, and the bulkhead and door to be tested. The door should be blocked to simulate possible jamming from the top, bottom, and sides (closing and locking alone may not be adequate to simulate all possible jamming). If the fragments from the broken door could cause an obstruction to the escape routes for passenger emergency egress, and if an emergency evacuation demonstration is required by airworthiness regulations or operating rules, consideration should be given to include the passengers in the test.

For emergency evacuation demonstrations with passengers, refer to § 25.803(c), Amendment 25-

15. (Amendment 25-47)

(ii) Two participants representing a pilot in the left crew seat and a copilot in the right crew seat should be used for the test. They should be persons with no special escape abilities. The crewmembers should be a female approximately 60-inches tall and weighing no more than 102 lbs and a male approximately 74-inches tall and weighing no less than 210 lbs.

The foregoing statures and weights represent the 5th percentile female to 95th percentile male occupants respectively. The female participant will be instructed to break the door and be the first person to egress without assistance from the male participant. Instructions for enhancing the egress should be limited to those instructions that will be provided in the FAA-approved Airplane Flight Manual (AFM) or on the related placards. (Amendment 25-47)

(iii) The test should be conducted in night conditions. If conducted in a hangar during the day, the hangar should be draped and taped so that all sunlight is prevented from entering the hangar. Similar conditions should exist if conducted at night either in or out of a hangar. Lighting may be allowed at ground level to aid in leaving the area near the airplane providing the lighting is kept low and shielded so it does not aid evacuating the airplane. Use of emergency lighting is acceptable. (Amendment 25-47)

(iv) Personnel participating should be informed of the purpose of the demonstration and of the safety precautions. Safety of participants is the responsibility of the applicant, and should be considered to prevent injuries to the participants without compromising the test results.

Participants may wear protective gear such as crash helmets, but the protective gear, tools, or any other device should not be used to break through the door. (Amendment 25-47)

(3) Paragraph (c). Refer to Appendix 11, FAA Memorandum, 01-115-11, Original Release: dated November 6, 2001, Revised December 3, 2002, “Subject: Certification of Strengthened Flightdeck Doors on Transport Category Airplanes.” This policy memorandum outlines acceptable means of compliance with this paragraph and many other regulatory requirements that were affected by Amendment 25-106. (Amendment 25-106) 46 - 60. [RESERVED]

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### Page 35

**19 SECTION 25.783 DOORS**

**61. REGULATION IN EFFECT AT ADOPTION OF PART 25.**

a. Regulation.

(a) Each cabin must have at least one easily accessible external door.

(b) There must be a means to lock and safeguard each external door against opening in flight (either inadvertently by persons or as a result of mechanical failure). Each external door must be openable from both the inside and the outside, even though persons may be crowded against the door on the inside of the airplane. Inward opening doors may be used if there are means to prevent occupants from crowding against the door to an extent that would interfere with the opening of the door. The means of opening must be simple and obvious and must be arranged and marked so that it can be readily located and operated, even in darkness. Auxiliary locking devices may be used.

(c) Each external door must be reasonably free from jamming as a result of fuselage deformation in a minor crash.

(d) Each external door must be located where persons using them will not be endangered by the propellers when appropriate operating procedures are used.

(e) There must be a provision for direct visual inspection of the locking mechanism by crewmembers to determine whether external doors, for which the initial opening movement is outward (including passenger, crew, service, and cargo doors), are fully locked. In addition, there must be a visual means to signal to appropriate crewmembers when normally used external doors are closed and fully locked.

(f) Cargo and service doors not suitable for use as an exit in an emergency need only meet paragraph (e) of this section and be safeguarded against opening in flight as a result of mechanical failure.

b. Guidance.

(l) Paragraphs (b) through (e). The requirements of these paragraphs apply to all cabin and pilot compartment external doors usable for entrance or egress. It is not restricted to the main cabin door. Cargo and service doors not suitable for emergency egress need only comply with § 25.783(e) and be safeguarded against opening in flight as a result of mechanical failure.

(Amendment 25-0)

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(2) Paragraph (b). Auxiliary locking devices. (Amendment 25-0)

(i) The use of auxiliary locking devices is permitted. Such devices would include dual locking handles, other types of locking and safety devices, two position handles, and dual operation handles (where one operation such as pushing or pulling on the handle unlocks the latching mechanism and the second operation of turning the handle unlatches the door for opening). Auxiliary locking devices should be used only as an additional safety factor and should not be used as a means of correcting an inadequate design of the primary locking or latching means. The advantages to be gained from the installation of auxiliary or dual locking devices (safety chains and dual handle main locking means) should be weighed against the need to easily and rapidly open the door in case of emergencies so that the overall level of safety is as high as practicable. (Amendment 25-0)

(ii) All locking or safety means, including safety chains and latches of any kind, should be so positioned and designed that their presence, location and means of operation are obvious to one not familiar with door designs. (Amendment 25-0) (A) The means of fastening safety devices should be sufficiently simple to make removal easy. (Amendment 25-0) (B) Any emergency release mechanism installed to release the safety device should operate with a simple motion and upon the application of relatively small forces.

(Amendment 25-0) (C) All locking devices should be readily operable from both inside and outside of the airplane and be appropriately marked both inside and outside. (Amendment 25-0)

(iii) Auxiliary safety devices meeting the standards of paragraph (ii) above may be fastened in place during the entire flight. It will not be necessary to have such devices unlatched during takeoff and landing. Auxiliary safety devices such as safety chains or bars that do not meet the standards of paragraph (ii) above may be used provided operating instructions are installed at or near the device and a placard is installed requiring the removal of such devices prior to takeoff and landing. For related guidance, Refer to paragraph 351b(3). (Amendment 25-

0)

(3) Paragraph (b). Power operated external doors. Power operated doors should be so designed that the door can be opened by manual means even when power is inactivated. The loss of power should not cause the door to become unlatched. Since emergency landings, such as the wheels-up condition, may result in the severance of electrical wires or rupture of hydraulic and pneumatic lines, the power which may be needed for operation of the doors or exits may be lost. Similarly, it is conceivable that under emergency conditions, the electrical power source may be purposely interrupted to reduce the possibility of fire. (Amendment 25-0)

(4) Paragraphs (b) and (e). Means for safeguarding against inadvertent opening in flight. Auxiliary locking devices may be used to reduce the probability of inadvertent opening in flight provided they meet the standards and conditions covered above. (Amendment 25-0)

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(i) It is acceptable to create a limited access zone in front of the door to eliminate the possibility of a passenger using the door handle as a steadying means and thereby inadvertently opening the door. Although providing a restricted zone by means of a barrier may appear to conflict with the requirements of § 25.813 for an unobstructed passageway to Type I, and Type II emergency exits, it is considered that it would contribute sufficiently to the overall safety of the airplane occupants to be permitted. This device may be a rope, chain, rigid bar or gate. Such installations should be waist high to provide the maximum benefits for an adult and the end fastenings should be simple to make removal easy. It is not considered acceptable to install full-length auxiliary doors, but waist-high rigid gates would be acceptable provided they open toward the door and will not block the opening of the cabin door in any way. The locking means should be one, which could be easily overridden such as a spring-loaded ball type latch.

(Amendment 25-0)

(ii) Flexible gates such as those made from webbing are not acceptable on the basis that persons may become entangled during an emergency egress. The use of a barrier to prevent persons from inadvertently opening the door in flight does not eliminate the need for a safety means to provide for possible malfunctioning of the primary locking mechanism; however, the auxiliary safety means covered above may eliminate the need for a restricted zone. (Amendment 25-0)

(5) Paragraph (e). Direct visual inspection. The means of complying with paragraph

(e) of this section will depend upon the type of door and locking mechanism used. In all cases there should be provisions to ascertain that an unsatisfactory condition does not exist after closing the door. In some instances a central window for viewing the position of the mechanism may be sufficient while other cases may require one or more windows in the door frame to permit inspection of the bayonet location relative to that portion of the lock in the door frame.

The need for or the number and location of inspection openings or windows will depend on the type of door and locking mechanism used. (Amendment 25-0)

(6) Paragraph (e). Visual indicating system. The objective herein is to be able to ascertain by visual means that the door or locking means is sufficiently engaged to eliminate hazards emanating from an improperly closed door. Outward opening doors present a different problem from inward opening doors. (Amendment 25-0)

(i) The visual indicating system may consist of an indicator for each individual door, or a system connecting all doors in series. If the latter system is used, it need not necessarily show which door is not fully locked. (Amendment 25-0)

(ii) It is not necessary that more than one crewmember be able to ascertain by a visual signal that all external doors, normally used by the crew in supplying the airplane, or in loading and unloading passengers and cargo, are fully closed and locked. The visual signal should be located so that it may easily be seen by the appropriate crewmember from his station.

(Amendment 25-0)

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62. AMENDMENT 25-15, Effective October 24, 1967.

a. Regulation.

(a) Each cabin must have at least one easily accessible external door.

(b) There must be a means to lock and safeguard each external door against opening in flight (either inadvertently by persons or as a result of mechanical failure). Each external door must be openable from both the inside and the outside, even though persons may be crowded against the door on the inside of the airplane. Inward opening doors may be used if there are means to prevent occupants from crowding against the door to an extent that would interfere with the opening of the door. The means of opening must be simple and obvious and must be arranged and marked so that it can be readily located and operated, even in darkness. Auxiliary locking devices may be used.

(c) Each external door must be reasonably free from jamming as a result of fuselage deformation in a minor crash.

(d) Each external door must be located where persons using them will not be endangered by the propellers when appropriate operating procedures are used.

(e) There must be a provision for direct visual inspection of the locking mechanism by crewmembers to determine whether external doors, for which the initial opening movement is outward (including passenger, crew, service, and cargo doors), are fully locked. In addition, there must be a visual means to signal to appropriate crewmembers when normally used external doors are closed and fully locked.

(f) Cargo and service doors not suitable for use as an exit in an emergency need only meet paragraph (e) of this section and be safeguarded against opening in flight as a result of mechanical failure.

[(g) Each passenger entry door in the side of the fuselage must qualify as a Type A, Type I, or Type II passenger emergency exit and must meet the requirements of §§ 25.807 through 25.813 that apply to that type of passenger emergency exit. If an integral stair is installed at such a passenger entry door, the stair must be designed so that when subjected to the inertia forces specified in § 25.561, and following the collapse of one or more legs of the landing gear, it will not interfere to an extent that will reduce the effectiveness of emergency egress through the passenger entry door.]

b. Guidance.

(l) Paragraphs (b) through (e). The requirements of these paragraphs apply to all cabin and pilot compartment external doors usable for entrance or egress. It is not restricted to the

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23 main cabin door. Cargo and service doors not suitable for emergency egress need only comply with § 25.783(e) and be safeguarded against opening in flight as a result of mechanical failure.

(Amendment 25-0)

(2) Paragraph (b). Auxiliary locking devices. (Amendment 25-0)

(i) The use of auxiliary locking devices is permitted. Such devices would include dual locking handles, other types of locking and safety devices, two position handles, and dual operation handles (where one operation such as pushing or pulling on the handle unlocks the latching mechanism and the second operation of turning the handle unlatches the door for opening). Auxiliary locking devices should be used only as an additional safety factor and should not be used as a means of correcting an inadequate design of the primary locking or latching means. The advantages to be gained from the installation of auxiliary or dual locking devices (safety chains and dual handle main locking means) should be weighed against the need to easily and rapidly open the door in case of emergencies so that the overall level of safety is as high as practicable. (Amendment 25-0)

(ii) All locking or safety means, including safety chains and latches of any kind, should be so positioned and designed that their presence, location and means of operation are obvious to one not familiar with door designs. (Amendment 25-0) (A) The means of fastening safety devices should be sufficiently simple to make removal easy. (Amendment 25-0) (B) Any emergency release mechanism installed to release the safety device should operate with a simple motion and upon the application of relatively small forces.

(Amendment 25-0) (C) All locking devices should be readily operable from both inside and outside of the airplane and be appropriately marked both inside and outside. (Amendment 25-0)

(iii) Auxiliary safety devices meeting the standards of paragraph (ii) above may be fastened in place during the entire flight. It will not be necessary to have such devices unlatched during takeoff and landing. Auxiliary safety devices such as safety chains or bars that do not meet the standards of paragraph (ii) above may be used provided operating instructions are installed at or near the device and a placard is installed requiring the removal of such devices prior to takeoff and landing. For related guidance, Refer to paragraph 351b(3). (Amendment 25-

0)

(3) Paragraph (b). Power operated external doors. Power operated doors should be so designed that the door can be opened by manual means even when power is inactivated. The loss of power should not cause the door to become unlatched. Since emergency landings, such as the wheels-up condition, may result in the severance of electrical wires or rupture of hydraulic and pneumatic lines, the power which may be needed for operation of the doors or exits may be lost. Similarly, it is conceivable that under emergency conditions, the electrical power source may be purposely interrupted to reduce the possibility of fire. (Amendment 25-0)

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(4) Paragraphs (b) and (e). Means for safeguarding against inadvertent opening in flight. Auxiliary locking devices may be used to reduce the probability of inadvertent opening in flight provided they meet the standards and conditions covered above. (Amendment 25-0)

(i) It is acceptable to create a limited access zone in front of the door to eliminate the possibility of a passenger using the door handle as a steadying means and thereby inadvertently opening the door. Although providing a restricted zone by means of a barrier may appear to conflict with the requirements of § 25.813 for an unobstructed passageway to Type I, and Type II emergency exits, it is considered that it would contribute sufficiently to the overall safety of the airplane occupants to be permitted. This device may be a rope, chain, rigid bar or gate. Such installations should be waist high to provide the maximum benefits for an adult and the end fastenings should be simple to make removal easy. It is not considered acceptable to install full-length auxiliary doors, but waist-high rigid gates would be acceptable provided they open toward the door and will not block the opening of the cabin door in any way. The locking means should be one, which could be easily overridden such as a spring-loaded ball type latch.

(Amendment 25-0)

(ii) Flexible gates such as those made from webbing are not acceptable on the basis that persons may become entangled during an emergency egress. The use of a barrier to prevent persons from inadvertently opening the door in flight does not eliminate the need for a safety means to provide for possible malfunctioning of the primary locking mechanism; however, the auxiliary safety means covered above may eliminate the need for a restricted zone. (Amendment 25-0)

(5) Paragraph (e). Direct visual inspection. The means of complying with paragraph

(e) of this section will depend upon the type of door and locking mechanism used. In all cases there should be provisions to ascertain that an unsatisfactory condition does not exist after closing the door. In some instances a central window for viewing the position of the mechanism may be sufficient while other cases may require one or more windows in the door frame to permit inspection of the bayonet location relative to that portion of the lock in the door frame.

The need for or the number and location of inspection openings or windows will depend on the type of door and locking mechanism used. (Amendment 25-0)

(6) Paragraph (e). Visual indicating system. The objective herein is to be able to ascertain by visual means that the door or locking means is sufficiently engaged to eliminate hazards emanating from an improperly closed door. Outward opening doors present a different problem from inward opening doors. (Amendment 25-0)

(i) The visual indicating system may consist of an indicator for each individual door, or a system connecting all doors in series. If the latter system is used, it need not necessarily show which door is not fully locked. (Amendment 25-0)

(ii) It is not necessary that more than one crewmember be able to ascertain by a visual signal that all external doors, normally used by the crew in supplying the airplane, or in

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25 loading and unloading passengers and cargo, are fully closed and locked. The visual signal should be located so that it may easily be seen by the appropriate crewmember from his station.

(Amendment 25-0)

63. AMENDMENT 25-23, Effective May 8, 1970.

a. Regulation.

(a) Each cabin must have at least one easily accessible external door.

(b) There must be a means to lock and safeguard each external door against opening in flight (either inadvertently by persons or as a result of mechanical failure [or failure of a single structural element]). Each external door must be openable from both the inside and the outside, even though persons may be crowded against the door on the inside of the airplane. Inward opening doors may be used if there are means to prevent occupants from crowding against the door to an extent that would interfere with the opening of the door. The means of opening must be simple and obvious and must be arranged and marked so that it can be readily located and operated, even in darkness. Auxiliary locking devices may be used.

(c) Each external door must be reasonably free from jamming as a result of fuselage deformation in a minor crash.

(d) Each external door must be located where persons using them will not be endangered by the propellers when appropriate operating procedures are used.

(e) There must be a provision for direct visual inspection of the locking mechanism by crewmembers to determine whether external doors, for which the initial opening movement is outward (including passenger, crew, service, and cargo doors), are fully locked. In addition, there must be a visual means to signal to appropriate crewmembers when normally used external doors are closed and fully locked.

(f) Cargo and service doors not suitable for use as an exit in an emergency need only meet paragraph (e) of this section and be safeguarded against opening in flight as a result of mechanical failure [or failure of a single structural element].

(g) Each passenger entry door in the side of the fuselage must qualify as a Type A, Type I, or Type II passenger emergency exit and must meet the requirements of §§ 25.807 through 25.813 that apply to that type of passenger emergency exit. If an integral stair is installed at such a passenger entry door, the stair must be designed so that when subjected to the inertia forces specified in § 25.561, and following the collapse of one or more legs of the landing gear, it will not interfere to an extent that will reduce the effectiveness of emergency egress through the passenger entry door.

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b. Guidance.

(l) Paragraphs (b) through (e). The requirements of these paragraphs apply to all cabin and pilot compartment external doors usable for entrance or egress. It is not restricted to the main cabin door. Cargo and service doors not suitable for emergency egress need only comply with § 25.783(e) and be safeguarded against opening in flight as a result of mechanical failure.

(Amendment 25-0)

(2) Paragraph (b). Auxiliary locking devices. (Amendment 25-0)

(i) The use of auxiliary locking devices is permitted. Such devices would include dual locking handles, other types of locking and safety devices, two position handles, and dual operation handles (where one operation such as pushing or pulling on the handle unlocks the latching mechanism and the second operation of turning the handle unlatches the door for opening). Auxiliary locking devices should be used only as an additional safety factor and should not be used as a means of correcting an inadequate design of the primary locking or latching means. The advantages to be gained from the installation of auxiliary or dual locking devices (safety chains and dual handle main locking means) should be weighed against the need to easily and rapidly open the door in case of emergencies so that the overall level of safety is as high as practicable. (Amendment 25-0)

(ii) All locking or safety means, including safety chains and latches of any kind, should be so positioned and designed that their presence, location and means of operation are obvious to one not familiar with door designs. (Amendment 25-0) (A) The means of fastening safety devices should be sufficiently simple to make removal easy. (Amendment 25-0) (B) Any emergency release mechanism installed to release the safety device should operate with a simple motion and upon the application of relatively small forces.

(Amendment 25-0) (C) All locking devices should be readily operable from both inside and outside of the airplane and be appropriately marked both inside and outside. (Amendment 25-0)

(iii) Auxiliary safety devices meeting the standards of paragraph (ii) above may be fastened in place during the entire flight. It will not be necessary to have such devices unlatched during takeoff and landing. Auxiliary safety devices such as safety chains or bars that do not meet the standards of paragraph (ii) above may be used provided operating instructions are installed at or near the device and a placard is installed requiring the removal of such devices prior to takeoff and landing. For related guidance, Refer to paragraph 351b(3). (Amendment 25-

0)

(3) Paragraph (b). Power operated external doors. Power operated doors should be so designed that the door can be opened by manual means even when power is inactivated. The

### Page 43

27 loss of power should not cause the door to become unlatched. Since emergency landings, such as the wheels-up condition, may result in the severance of electrical wires or rupture of hydraulic and pneumatic lines, the power which may be needed for operation of the doors or exits may be lost. Similarly, it is conceivable that under emergency conditions, the electrical power source may be purposely interrupted to reduce the possibility of fire. (Amendment 25-0)

(4) Paragraphs (b) and (e). Means for safeguarding against inadvertent opening in flight. Auxiliary locking devices may be used to reduce the probability of inadvertent opening in flight provided they meet the standards and conditions covered above. (Amendment 25-0)

(i) It is acceptable to create a limited access zone in front of the door to eliminate the possibility of a passenger using the door handle as a steadying means and thereby inadvertently opening the door. Although providing a restricted zone by means of a barrier may appear to conflict with the requirements of § 25.813 for an unobstructed passageway to Type I, and Type II emergency exits, it is considered that it would contribute sufficiently to the overall safety of the airplane occupants to be permitted. This device may be a rope, chain, rigid bar or gate. Such installations should be waist high to provide the maximum benefits for an adult and the end fastenings should be simple to make removal easy. It is not considered acceptable to install full-length auxiliary doors, but waist-high rigid gates would be acceptable provided they open toward the door and will not block the opening of the cabin door in any way. The locking means should be one, which could be easily overridden such as a spring-loaded ball type latch.

(Amendment 25-0)

(ii) Flexible gates such as those made from webbing are not acceptable on the basis that persons may become entangled during an emergency egress. The use of a barrier to prevent persons from inadvertently opening the door in flight does not eliminate the need for a safety means to provide for possible malfunctioning of the primary locking mechanism; however, the auxiliary safety means covered above may eliminate the need for a restricted zone. (Amendment 25-0)

(5) Paragraph (e). Direct visual inspection. The means of complying with paragraph

(e) of this section will depend upon the type of door and locking mechanism used. In all cases there should be provisions to ascertain that an unsatisfactory condition does not exist after closing the door. In some instances a central window for viewing the position of the mechanism may be sufficient while other cases may require one or more windows in the door frame to permit inspection of the bayonet location relative to that portion of the lock in the door frame.

The need for or the number and location of inspection openings or windows will depend on the type of door and locking mechanism used. (Amendment 25-0)

(6) Paragraph (e). Visual indicating system. The objective herein is to be able to ascertain by visual means that the door or locking means is sufficiently engaged to eliminate hazards emanating from an improperly closed door. Outward opening doors present a different problem from inward opening doors. (Amendment 25-0)

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(i) The visual indicating system may consist of an indicator for each individual door, or a system connecting all doors in series. If the latter system is used, it need not necessarily show which door is not fully locked. (Amendment 25-0)

(ii) It is not necessary that more than one crewmember be able to ascertain by a visual signal that all external doors, normally used by the crew in supplying the airplane, or in loading and unloading passengers and cargo, are fully closed and locked. The visual signal should be located so that it may easily be seen by the appropriate crewmember from his station.

(Amendment 25-0)

64. AMENDMENT 25-54, Effective October 14, 1980.

a. Regulation.

(a) Each cabin must have at least one easily accessible external door.

(b) There must be a means to lock and safeguard each external door against opening in flight (either inadvertently by persons or as a result of mechanical failure or failure of a single structural element [either during or after closure]). Each external door must be openable from both the inside and the outside, even though persons may be crowded against the door on the inside of the airplane. Inward opening doors may be used if there are means to prevent occupants from crowding against the door to an extent that would interfere with the opening of the door. The means of opening must be simple and obvious and must be arranged and marked so that it can be readily located and operated, even in darkness. Auxiliary locking devices may be used.

(c) Each external door must be reasonably free from jamming as a result of fuselage deformation in a minor crash.

(d) Each external door must be located where persons using them will not be endangered by the propellers when appropriate operating procedures are used.

[(e) There must be a provision for direct visual inspection of the locking mechanism to determine if external doors, for which the initial opening movement is not inward (including passenger, crew, service, and cargo doors), are fully closed and locked.

The provision must be discernible under operational lighting conditions by appropriate crewmembers using a flashlight or equivalent lighting source. In addition, there must be a visual warning means to signal the appropriate flight crewmembers if any external door is not fully closed and locked. The means must be designed such that any failure or combination of failures that would result in an erroneous closed and locked indication is improbable for doors for which the initial opening movement is not inward.

(f) External doors must have provisions to prevent the initiation of pressurization of the airplane to an unsafe level if the door is not fully closed and locked. In addition,

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29 it must be shown by safety analysis that inadvertent opening is extremely improbable.] [(g)] Cargo and service doors not suitable for use as an exit in an emergency need only meet paragraph (e) of this section and be safeguarded against opening in flight as a result of mechanical failure or failure of a single structural element.

(h) Each passenger entry door in the side of the fuselage must qualify as a Type A, Type I, or Type II passenger emergency exit and must meet the requirements of §§ 25.807 through 25.813 that apply to that type of passenger emergency exit.

(i) If an integral stair is installed in a passenger entry door that is qualified as a passenger emergency exit, the stair must be designed so that under the following conditions the effectiveness of passenger emergency egress will not be impaired:

(1) The door, integral stair, and operating mechanism have been subjected to the inertia forces specified in § 25.561(b)(3), acting separately relative to the surrounding structure.

[(2) The airplane is in the normal ground attitude and in each of the attitudes corresponding to collapse of one or more legs of the landing gear.

(j) All lavatory doors must be designed to preclude anyone from becoming trapped inside the lavatory, and if a locking mechanism is installed, it be capable of being unlocked from the outside without the aid of special tools.]

b. Guidance.

(1) Refer to § 25.809 for related requirements, and AC 25.783-1, “Fuselage, Doors, Hatches, and Exits,” dated 12/10/86, for related guidance. (Amendment 25-54)

(2) Paragraph (b). Protection against inadvertent exit door openings is required, but at the same time, a single-motion handle operation to open a passenger door should be provided to facilitate emergency egress. Auxiliary locking devices that complicate the door opening process may be accepted as necessary, though undesirable, if it can be substantiated that there is no other practicable means of protecting against inadvertent exit door opening. (Amendment 25-54)

(i) Auxiliary locking devices that may initially be assumed to be necessary, in fact might be eliminated by assuring that the door is designed in accordance with human factors principles. A door that is opened by moving a handle from the up position to a down position represents a design contrary to the convention believed to be familiar to most people in the aircraft industry. Therefore, this design may lend itself to contributing to an inadvertent door opening, as has actually happened. In addition, a door handle that is in the up position when the door is closed lends itself to more easily being used as a handhold in flight, which may result in an inadvertent opening. The threat inherent in this design would practically mandate the inclusion of auxiliary locking devices, to the possible detriment of emergency egress capability.

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30 On the other hand, a door handle which operates in a conventional manner (i.e., moves up to open, moves down to close) is not as prone to inappropriate operation, nor is it in a location as susceptible for use as a handhold in flight. Consequently, this design, in addition to being more user-friendly from a human factors viewpoint, may eliminate any need for auxiliary locking devices. (Amendment 25-54)

(ii) Handles which operate in a rotary manner (in a plane parallel to that of the door) are not known to have been implicated in any incidents as noted above, nor has clockwise versus counterclockwise rotary motion been known to be controversial in this regard (except that counterclockwise may be the most universally accepted convention for opening jars, faucets, etc.). Likewise, these handles have not been considered to represent the attractive handhold devices in flight that other types of handles might and, furthermore, they require a deliberate effort to actuate. (Amendment 25-54)

(iii) When it can be substantiated to the satisfaction of the FAA that auxiliary locking devices are necessary to comply with the inadvertent door opening requirements of §§ 25.783(a) and 25.809(f), and it is not through design defect that these devices are provided, any potentially adverse impact of these devices on emergency egress must be minimized through adherence to the available guidance pertinent to auxiliary locking devices. "Design defect" in this context may reasonably be considered to include designs which neglect to address known human factors concerns as highlighted herein. Auxiliary locking devices which are deemed to be not simple and obvious, are not acceptable. Devices which are hidden by design or color, recessed, contoured, camouflaged, or otherwise concealed to the degree that a naive person may need to read a placard to determine how to open the door are not simple and obvious, and are therefore not acceptable. Suitable demonstrations may be required to substantiate acceptability in this regard. (Amendment 25-54)

(3) Paragraphs (b) through (e). The requirements of these paragraphs apply to all cabin and pilot compartment external doors usable for entrance or egress. It is not restricted to the main cabin door. (Amendment 25-0)

(4) Paragraph (b). Auxiliary locking devices. (Amendment 25-0)

(i) The use of auxiliary locking devices is permitted. Such devices would include dual locking handles, other types of locking and safety devices, two position handles, and dual operation handles (where one operation such as pushing or pulling on the handle unlocks the latching mechanism and the second operation of turning the handle unlatches the door for opening). Auxiliary locking devices should be used only as an additional safety factor and should not be used as a means of correcting an inadequate design of the primary locking or latching means. The advantages to be gained from the installation of auxiliary or dual locking devices (safety chains and dual handle main locking means) should be weighed against the need to easily and rapidly open the door in case of emergencies so that the overall level of safety is as high as practicable. (Amendment 25-0)

### Page 47

(ii) All locking or safety means, including safety chains and latches of any kind, should be so positioned and designed that their presence, location and means of operation are obvious to one not familiar with door designs. (Amendment 25-0) (A) The means of fastening safety devices should be sufficiently simple to make removal easy. (Amendment 25-0) (B) Any emergency release mechanism installed to release the safety device should operate with a simple motion and upon the application of relatively small forces.

(Amendment 25-0) (C) All locking devices should be readily operable from both inside and outside of the airplane and be appropriately marked both inside and outside. (Amendment 25-0)

(iii) Auxiliary safety devices meeting the standards of paragraph (ii) above may be fastened in place during the entire flight. It will not be necessary to have such devices unlatched during takeoff and landing. Auxiliary safety devices such as safety chains or bars that do not meet the standards of paragraph (ii) above may be used provided operating instructions are installed at or near the device and a placard is installed requiring the removal of such devices prior to takeoff and landing. For related guidance, Refer to paragraph 351b(3). (Amendment 25-

0)

(5) Paragraph (b). Power operated external doors. Power operated doors should be so designed that the door can be opened by manual means even when power is inactivated. The loss of power should not cause the door to become unlatched. Since emergency landings, such as the wheels-up condition, may result in the severance of electrical wires or rupture of hydraulic and pneumatic lines, the power which may be needed for operation of the doors or exits may be lost. Similarly, it is conceivable that under emergency conditions, the electrical power source may be purposely interrupted to reduce the possibility of fire. (Amendment 25-0)

(i) It is acceptable to create a limited access zone in front of the door to eliminate the possibility of a passenger using the door handle as a steadying means and thereby inadvertently opening the door. Although providing a restricted zone by means of a barrier may appear to conflict with the requirements of § 25.813 for an unobstructed passageway to Type I, and Type II emergency exits, it is considered that it would contribute sufficiently to the overall safety of the airplane occupants to be permitted. This device may be a rope, chain, rigid bar or gate. Such installations should be waist high to provide the maximum benefits for an adult and the end fastenings should be simple to make removal easy. It is not considered acceptable to install full-length auxiliary doors, but waist-high rigid gates would be acceptable provided they open toward the door and will not block the opening of the cabin door in any way. The locking means should be one, which could be easily overridden such as a spring-loaded ball type latch.

(Amendment 25-0)

(ii) Flexible gates such as those made from webbing are not acceptable on the basis that persons may become entangled during an emergency egress. The use of a barrier to prevent persons from inadvertently opening the door in flight does not eliminate the need for a safety

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32 means to provide for possible malfunctioning of the primary locking mechanism; however, the auxiliary safety means covered above may eliminate the need for a restricted zone. (Amendment 25-0)

(6) Paragraph (e). Visual indicating system. The objective herein is to be able to ascertain by visual means that the door or locking means is sufficiently engaged to eliminate hazards emanating from an improperly closed door. Outward opening doors present a different problem from inward opening doors. (Amendment 25-0)

(i) The visual indicating system may consist of an indicator for each individual door, or a system connecting all doors in series. If the latter system is used, it need not necessarily show which door is not fully locked. (Amendment 25-0)

(ii) It is not necessary that more than one crewmember be able to ascertain by a visual signal that all external doors, normally used by the crew in supplying the airplane, or in loading and unloading passengers and cargo, are fully closed and locked. The visual signal should be located so that it may easily be seen by the appropriate crewmember from his station.

(Amendment 25-0)

65. AMENDMENT 25-72, Effective August 20, 1990.

a. Regulation.

(a) Each cabin must have at least one easily accessible external door.

(b) There must be a means to lock and safeguard each external door against opening in flight (either inadvertently by persons or as a result of mechanical failure or failure of a single structural element either during or after closure). Each external door must be openable from both the inside and the outside, even though persons may be crowded against the door on the inside of the airplane. Inward opening doors may be used if there are means to prevent occupants from crowding against the door to an extent that would interfere with the opening of the door. The means of opening must be simple and obvious and must be arranged and marked so that it can be readily located and operated, even in darkness. Auxiliary locking devices may be used.

(c) Each external door must be reasonably free from jamming as a result of fuselage deformation in a minor crash.

(d) Each external door must be located where persons using them will not be endangered by the propellers when appropriate operating procedures are used.

(e) There must be a provision for direct visual inspection of the locking mechanism to determine if external doors, for which the initial opening movement is not inward (including passenger, crew, service, and cargo doors), are fully closed and locked.

The provision must be discernible under operational lighting conditions by appropriate crewmembers using a flashlight or equivalent lighting source. In

### Page 49

33 addition, there must be a visual warning means to signal the appropriate flight crewmembers if any external door is not fully closed and locked. The means must be designed such that any failure or combination of failures that would result in an erroneous closed and locked indication is improbable for doors for which the initial opening movement is not inward.

(f) External doors must have provisions to prevent the initiation of pressurization of the airplane to an unsafe level if the door is not fully closed and locked. In addition, it must be shown by safety analysis that inadvertent opening is extremely improbable.

[(g) Cargo and service doors not suitable for use as emergency exits need only meet paragraphs (e) and (f) of this section and be safeguarded against opening in flight as a result of mechanical failure or failure of a single structural element.]

(h) Each passenger entry door in the side of the fuselage must qualify as a Type A, Type I, or Type II passenger emergency exit and must meet the requirements of §§ 25.807 through 25.813 that apply to that type of passenger emergency exit.

(i) If an integral stair is installed in a passenger entry door that is qualified as a passenger emergency exit, the stair must be designed so that under the following conditions the effectiveness of passenger emergency egress will not be impaired:

(1) The door, integral stair, and operating mechanism have been subjected to the inertia forces specified in § 25.561(b)(3), acting separately relative to the surrounding structure.

(2) The airplane is in the normal ground attitude and in each of the attitudes corresponding to collapse of one or more legs of the landing gear.

(j) All lavatory doors must be designed to preclude anyone from becoming trapped inside the lavatory, and if a locking mechanism is installed, it be capable of being unlocked from the outside without the aid of special tools.

b. Guidance.

(1) Refer to § 25.809 for related requirements, and AC 25.783-1, “Fuselage, Doors, Hatches, and Exits,” dated 12/10/86, for related guidance. (Amendment 25-54)

(2) Paragraph (b). Protection against inadvertent exit door openings is required, but at the same time, a single-motion handle operation to open a passenger door should be provided to facilitate emergency egress. Auxiliary locking devices that complicate the door opening process may be accepted as necessary, though undesirable, if it can be substantiated that there is no other practicable means of protecting against inadvertent exit door opening. (Amendment 25-54)

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(i) Auxiliary locking devices that may initially be assumed to be necessary, in fact might be eliminated by assuring that the door is designed in accordance with human factors principles. A door that is opened by moving a handle from the up position to a down position represents a design contrary to the convention believed to be familiar to most people in the aircraft industry. Therefore, this design may lend itself to contributing to an inadvertent door opening, as has actually happened. In addition, a door handle that is in the up position when the door is closed lends itself to more easily being used as a handhold in flight, which may result in an inadvertent opening. The threat inherent in this design would practically mandate the inclusion of auxiliary locking devices, to the possible detriment of emergency egress capability.

On the other hand, a door handle which operates in a conventional manner (i.e., moves up to open, moves down to close) is not as prone to inappropriate operation, nor is it in a location as susceptible for use as a handhold in flight. Consequently, this design, in addition to being more user-friendly from a human factors viewpoint, may eliminate any need for auxiliary locking devices. (Amendment 25-54)

(ii) Handles which operate in a rotary manner (in a plane parallel to that of the door) are not known to have been implicated in any incidents as noted above, nor has clockwise versus counterclockwise rotary motion been known to be controversial in this regard (except that counterclockwise may be the most universally accepted convention for opening jars, faucets, etc.). Likewise, these handles have not been considered to represent the attractive handhold devices in flight that other types of handles might and, furthermore, they require a deliberate effort to actuate. (Amendment 25-54)

(iii) When it can be substantiated to the satisfaction of the FAA that auxiliary locking devices are necessary to comply with the inadvertent door opening requirements of §§ 25.783(a) and 25.809(f) (Amendment 25-72, 25.810(a)), and it is not through design defect that these devices are provided, any potentially adverse impact of these devices on emergency egress must be minimized through adherence to the available guidance pertinent to auxiliary locking devices. "Design defect" in this context may reasonably be considered to include designs which neglect to address known human factors concerns as highlighted herein.

Auxiliary locking devices which are deemed to be not simple and obvious, are not acceptable.

Devices which are hidden by design or color, recessed, contoured, camouflaged, or otherwise concealed to the degree that a naive person may need to read a placard to determine how to open the door are not simple and obvious, and are therefore not acceptable. Suitable demonstrations may be required to substantiate acceptability in this regard. (Amendment 25-54)

(3) Paragraphs (b) through (e). The requirements of these paragraphs apply to all cabin and pilot compartment external doors usable for entrance or egress. It is not restricted to the main cabin door. (Amendment 25-0)

(4) Paragraph (b). Auxiliary locking devices. (Amendment 25-0)

(i) The use of auxiliary locking devices is permitted. Such devices would include dual locking handles, other types of locking and safety devices, two position handles, and dual operation handles (where one operation such as pushing or pulling on the handle unlocks the latching mechanism and the second operation of turning the handle unlatches the door for

### Page 51

35 opening). Auxiliary locking devices should be used only as an additional safety factor and should not be used as a means of correcting an inadequate design of the primary locking or latching means. The advantages to be gained from the installation of auxiliary or dual locking devices (safety chains and dual handle main locking means) should be weighed against the need to easily and rapidly open the door in case of emergencies so that the overall level of safety is as high as practicable. (Amendment 25-0)

(ii) All locking or safety means, including safety chains and latches of any kind, should be so positioned and designed that their presence, location and means of operation are obvious to one not familiar with door designs. (Amendment 25-0) (A) The means of fastening safety devices should be sufficiently simple to make removal easy. (Amendment 25-0) (B) Any emergency release mechanism installed to release the safety device should operate with a simple motion and upon the application of relatively small forces.

(Amendment 25-0) (C) All locking devices should be readily operable from both inside and outside of the airplane and be appropriately marked both inside and outside. (Amendment 25-0)

(iii) Auxiliary safety devices meeting the standards of paragraph (ii) above may be fastened in place during the entire flight. It will not be necessary to have such devices unlatched during takeoff and landing. Auxiliary safety devices such as safety chains or bars that do not meet the standards of paragraph (ii) above may be used provided operating instructions are installed at or near the device and a placard is installed requiring the removal of such devices prior to takeoff and landing. For related guidance, Refer to paragraph 351b(3). (Amendment 25-

0)

(5) Paragraph (b). Power operated external doors. Power operated doors should be so designed that the door can be opened by manual means even when power is inactivated. The loss of power should not cause the door to become unlatched. Since emergency landings, such as the wheels-up condition, may result in the severance of electrical wires or rupture of hydraulic and pneumatic lines, the power which may be needed for operation of the doors or exits may be lost. Similarly, it is conceivable that under emergency conditions, the electrical power source may be purposely interrupted to reduce the possibility of fire. (Amendment 25-0)

(i) It is acceptable to create a limited access zone in front of the door to eliminate the possibility of a passenger using the door handle as a steadying means and thereby inadvertently opening the door. Although providing a restricted zone by means of a barrier may appear to conflict with the requirements of § 25.813 for an unobstructed passageway to Type I, and Type II emergency exits, it is considered that it would contribute sufficiently to the overall safety of the airplane occupants to be permitted. This device may be a rope, chain, rigid bar or gate. Such installations should be waist high to provide the maximum benefits for an adult and the end fastenings should be simple to make removal easy. It is not considered acceptable to install full-length auxiliary doors, but waist-high rigid gates would be acceptable provided they

### Page 52

36 open toward the door and will not block the opening of the cabin door in any way. The locking means should be one, which could be easily overridden such as a spring-loaded ball type latch.

(Amendment 25-0)

(ii) Flexible gates such as those made from webbing are not acceptable on the basis that persons may become entangled during an emergency egress. The use of a barrier to prevent persons from inadvertently opening the door in flight does not eliminate the need for a safety means to provide for possible malfunctioning of the primary locking mechanism; however, the auxiliary safety means covered above may eliminate the need for a restricted zone. (Amendment 25-0)

(6) Paragraph (e). Visual indicating system. The objective herein is to be able to ascertain by visual means that the door or locking means is sufficiently engaged to eliminate hazards emanating from an improperly closed door. Outward opening doors present a different problem from inward opening doors. (Amendment 25-0)

(i) The visual indicating system may consist of an indicator for each individual door, or a system connecting all doors in series. If the latter system is used, it need not necessarily show which door is not fully locked. (Amendment 25-0)

(ii) It is not necessary that more than one crewmember be able to ascertain by a visual signal that all external doors, normally used by the crew in supplying the airplane, or in loading and unloading passengers and cargo, are fully closed and locked. The visual signal should be located so that it may easily be seen by the appropriate crewmember from his station.

(Amendment 25-0)

66. AMENDMENT 25-88, Effective December 9, 1996.

a. Regulation.

(a) Each cabin must have at least one easily accessible external door.

(b) There must be a means to lock and safeguard each external door against opening in flight (either inadvertently by persons or as a result of mechanical failure or failure of a single structural element either during or after closure). Each external door must be openable from both the inside and the outside, even though persons may be crowded against the door on the inside of the airplane. Inward opening doors may be used if there are means to prevent occupants from crowding against the door to an extent that would interfere with the opening of the door. The means of opening must be simple and obvious and must be arranged and marked so that it can be readily located and operated, even in darkness. Auxiliary locking devices may be used.

(c) Each external door must be reasonably free from jamming as a result of fuselage deformation in a minor crash.

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(d) Each external door must be located where persons using them will not be endangered by the propellers when appropriate operating procedures are used.

(e) There must be a provision for direct visual inspection of the locking mechanism to determine if external doors, for which the initial opening movement is not inward (including passenger, crew, service, and cargo doors), are fully closed and locked.

The provision must be discernible under operational lighting conditions by appropriate crewmembers using a flashlight or equivalent lighting source. In addition, there must be a visual warning means to signal the appropriate flight crewmembers if any external door is not fully closed and locked. The means must be designed such that any failure or combination of failures that would result in an erroneous closed and locked indication is improbable for doors for which the initial opening movement is not inward.

(f) External doors must have provisions to prevent the initiation of pressurization of the airplane to an unsafe level if the door is not fully closed and locked. In addition, it must be shown by safety analysis that inadvertent opening is extremely improbable.

(g) Cargo and service doors not suitable for use as emergency exits only meet paragraphs (e) and (f) of this section and be safeguarded against opening in flight as a result of mechanical failure or failure of a single structural element.

[(h) Each passenger entry door in the side of the fuselage must meet the applicable requirements of §§ 25.807 through 25.813 for a Type II or larger passenger emergency exit.]

(i) If an integral stair is installed in a passenger entry door that is qualified as a passenger emergency exit, the stair must be designed so that under the following conditions the effectiveness of passenger emergency egress will not be impaired:

(1) The door, integral stair, and operating mechanism have been subjected to the inertia forces specified in § 25.561(b)(3), acting separately relative to the surrounding structure.

(2) The airplane is in the normal ground attitude and in each of the attitudes corresponding to collapse of one or more legs of the landing gear.

(j) All lavatory doors must be designed to preclude anyone from becoming trapped inside the lavatory, and if a locking mechanism is installed, it be capable of being unlocked from the outside without the aid of special tools.

b. Guidance.

(1) Refer to § 25.809 for related requirements, and AC 25.783-1, “Fuselage, Doors, Hatches, and Exits,” dated 12/10/86, for related guidance. (Amendment 25-54)

### Page 54

(2) Paragraph (b). Protection against inadvertent exit door openings is required, but at the same time, a single-motion handle operation to open a passenger door should be provided to facilitate emergency egress. Auxiliary locking devices that complicate the door opening process may be accepted as necessary, though undesirable, if it can be substantiated that there is no other practicable means of protecting against inadvertent exit door opening. (Amendment 25-54)

(i) Auxiliary locking devices that may initially be assumed to be necessary, in fact might be eliminated by assuring that the door is designed in accordance with human factors principles. A door that is opened by moving a handle from the up position to a down position represents a design contrary to the convention believed to be familiar to most people in the aircraft industry. Therefore, this design may lend itself to contributing to an inadvertent door opening, as has actually happened. In addition, a door handle that is in the up position when the door is closed lends itself to more easily being used as a handhold in flight, which may result in an inadvertent opening. The threat inherent in this design would practically mandate the inclusion of auxiliary locking devices, to the possible detriment of emergency egress capability.

On the other hand, a door handle which operates in a conventional manner (i.e., moves up to open, moves down to close) is not as prone to inappropriate operation, nor is it in a location as susceptible for use as a handhold in flight. Consequently, this design, in addition to being more user-friendly from a human factors viewpoint, may eliminate any need for auxiliary locking devices. (Amendment 25-54)

(ii) Handles which operate in a rotary manner (in a plane parallel to that of the door) are not known to have been implicated in any incidents as noted above, nor has clockwise versus counterclockwise rotary motion been known to be controversial in this regard (except that counterclockwise may be the most universally accepted convention for opening jars, faucets, etc.). Likewise, these handles have not been considered to represent the attractive handhold devices in flight that other types of handles might and, furthermore, they require a deliberate effort to actuate. (Amendment 25-54)

(iii) When it can be substantiated to the satisfaction of the FAA that auxiliary locking devices are necessary to comply with the inadvertent door opening requirements of §§ 25.783(a) and 25.809(f) (Amendment 25-72, 25.810(a)), and it is not through design defect that these devices are provided, any potentially adverse impact of these devices on emergency egress must be minimized through adherence to the available guidance pertinent to auxiliary locking devices. "Design defect" in this context may reasonably be considered to include designs which neglect to address known human factors concerns as highlighted herein.

Auxiliary locking devices which are deemed to be not simple and obvious, are not acceptable.

Devices which are hidden by design or color, recessed, contoured, camouflaged, or otherwise concealed to the degree that a naive person may need to read a placard to determine how to open the door are not simple and obvious, and are therefore not acceptable. Suitable demonstrations may be required to substantiate acceptability in this regard. (Amendment 25-54)

(3) Paragraphs (b) through (e). The requirements of these paragraphs apply to all cabin and pilot compartment external doors usable for entrance or egress. It is not restricted to the main cabin door. (Amendment 25-0)

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(4) Paragraph (b). Auxiliary locking devices. (Amendment 25-0)

(i) The use of auxiliary locking devices is permitted. Such devices would include dual locking handles, other types of locking and safety devices, two position handles, and dual operation handles (where one operation such as pushing or pulling on the handle unlocks the latching mechanism and the second operation of turning the handle unlatches the door for opening). Auxiliary locking devices should be used only as an additional safety factor and should not be used as a means of correcting an inadequate design of the primary locking or latching means. The advantages to be gained from the installation of auxiliary or dual locking devices (safety chains and dual handle main locking means) should be weighed against the need to easily and rapidly open the door in case of emergencies so that the overall level of safety is as high as practicable. (Amendment 25-0)

(ii) All locking or safety means, including safety chains and latches of any kind, should be so positioned and designed that their presence, location and means of operation are obvious to one not familiar with door designs. (Amendment 25-0) (A) The means of fastening safety devices should be sufficiently simple to make removal easy. (Amendment 25-0) (B) Any emergency release mechanism installed to release the safety device should operate with a simple motion and upon the application of relatively small forces.

(Amendment 25-0) (C) All locking devices should be readily operable from both inside and outside of the airplane and be appropriately marked both inside and outside. (Amendment 25-0)

(iii) Auxiliary safety devices meeting the standards of paragraph (ii) above may be fastened in place during the entire flight. It will not be necessary to have such devices unlatched during takeoff and landing. Auxiliary safety devices such as safety chains or bars that do not meet the standards of paragraph (ii) above may be used provided operating instructions are installed at or near the device and a placard is installed requiring the removal of such devices prior to takeoff and landing. For related guidance, Refer to paragraph 351b(3). (Amendment 25-

0)

(5) Paragraph (b). Power operated external doors. Power operated doors should be so designed that the door can be opened by manual means even when power is inactivated. The loss of power should not cause the door to become unlatched. Since emergency landings, such as the wheels-up condition, may result in the severance of electrical wires or rupture of hydraulic and pneumatic lines, the power which may be needed for operation of the doors or exits may be lost. Similarly, it is conceivable that under emergency conditions, the electrical power source may be purposely interrupted to reduce the possibility of fire. (Amendment 25-0)

(i) It is acceptable to create a limited access zone in front of the door to eliminate the possibility of a passenger using the door handle as a steadying means and thereby

### Page 56

40 inadvertently opening the door. Although providing a restricted zone by means of a barrier may appear to conflict with the requirements of § 25.813 for an unobstructed passageway to Type I, and Type II emergency exits, it is considered that it would contribute sufficiently to the overall safety of the airplane occupants to be permitted. This device may be a rope, chain, rigid bar or gate. Such installations should be waist high to provide the maximum benefits for an adult and the end fastenings should be simple to make removal easy. It is not considered acceptable to install full-length auxiliary doors, but waist-high rigid gates would be acceptable provided they open toward the door and will not block the opening of the cabin door in any way. The locking means should be one, which could be easily overridden such as a spring-loaded ball type latch.

(Amendment 25-0)

(ii) Flexible gates such as those made from webbing are not acceptable on the basis that persons may become entangled during an emergency egress. The use of a barrier to prevent persons from inadvertently opening the door in flight does not eliminate the need for a safety means to provide for possible malfunctioning of the primary locking mechanism; however, the auxiliary safety means covered above may eliminate the need for a restricted zone. (Amendment 25-0)

(6) Paragraph (e). Visual indicating system. The objective herein is to be able to ascertain by visual means that the door or locking means is sufficiently engaged to eliminate hazards emanating from an improperly closed door. Outward opening doors present a different problem from inward opening doors. (Amendment 25-0)

(i) The visual indicating system may consist of an indicator for each individual door, or a system connecting all doors in series. If the latter system is used, it need not necessarily show which door is not fully locked. (Amendment 25-0)

(ii) It is not necessary that more than one crewmember be able to ascertain by a visual signal that all external doors, normally used by the crew in supplying the airplane, or in loading and unloading passengers and cargo, are fully closed and locked. The visual signal should be located so that it may easily be seen by the appropriate crewmember from his station.

(Amendment 25-0) 67 - 80. [RESERVED]

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**41 SECTION 25.785 SEATS, BERTHS, SAFETY BELTS, AND HARNESSES**

**81. REGULATION IN EFFECT AT ADOPTION OF PART 25.**

a. Regulation.

(a) Each seat, berth, safety belt, harness, and adjacent part of the airplane, at each station designated as occupiable during takeoff and landing, must be designed so that a person making proper use of these facilities will not suffer serious injury in an emergency landing as a result of the inertia forces specified in § 25.561.

(b) Each seat and berth must be approved.

(c) Each occupant must be protected from head injury by-

(1) A safety belt and shoulder harness that will prevent the head from contacting any injurious object;

(2) A safety belt plus the elimination of any injurious object within striking radius of the head; or

(3) Safety belt plus a cushioned rest that will support the arms, shoulders, head and spine.

(d) If the seat backs do not have a firm hand hold, there must be a hand grip or rail along each aisle to enable occupants to steady themselves while using the aisles in moderately rough air.

(e) Each projecting object that would injure persons seated or moving about the airplane in normal flight must be padded.

(f) Each berth must be designed so that the forward part has a padded end board, canvas diaphragm, or equivalent means that can withstand the static load reaction of the occupant when subjected to the forward inertia force specified in § 25.561. Berths must be free from corners and protuberances likely to cause serious injury to a person occupying the berth during emergency conditions.

(g) Each crewmember seat at flight deck stations must have provisions for a shoulder harness. These seats must meet strength requirements of paragraph (i) of this section.

(h) Cabin attendant seats must be in the passenger compartment near approved floor level emergency exits.

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(i) Each seat, berth, and its supporting structure, must be designed for an occupant weight of 170 pounds, considering the maximum load factors, inertia forces, and reactions between the occupant, seat, and safety belt or harness, at each relevant flight and ground load condition (including the emergency landing conditions prescribed in § 25.561). For berths, the forward inertia force must be considered in accordance with paragraph (f) of this section and need not be considered with respect to the safety belt. In addition-

(l) The structural analysis and testing of the seats, berths, and their supporting structures may be determined by-

(i) Assuming that the critical load in the forward, sideward, downward, and rearward directions (as determined from the prescribed flight, ground, and emergency landing conditions) acts separately; and

(ii) Using selected combinations of loads if the required strength in each specified direction is substantiated;

(2) Each pilot seat must be designed for the reactions resulting from the application of the pilot forces prescribed in § 25.395; and

(3) The inertia forces specified in § 25.561 must be multiplied by a factor of l.33 (instead of the fitting factor prescribed in § 25.625) in determining the strength of the attachment of-

(i) Each seat to the structure; and

(ii) Each belt or harness to seat or structure.

b. Guidance.

(1) Paragraph (a). In order for the seat belt to be effective, it should be positioned to lay across the hip bone and ideally be about 45 degrees from the horizontal. An acceptable range for this angle is 35 degrees to 55 degrees. An acceptable range for the shoulder harness is 30 degrees above to 5 degrees below the horizontal. Refer to ACs 25.785-1A, “Flight Attendant Seat and Torso Restraint System Installations,” dated 1/6/94, and 43.13-1A, “Acceptable Methods, Techniques, and Practices-Aircraft Inspection and Repair (with Errata Sheet),” dated 4/17/72, for related guidance. When testing a seat to demonstrate compliance with the static requirements of § 25.561, the testing should be conducted with an occupant center of gravity (CG) location as defined in NAS 809 (referenced in Technical Standard Order (TSO) C39) and AS8049 (referenced in the current version of TSO-C127). This CG location should be utilized in any airplane interface load analysis conducted. (Amendment 25-0)

(2) Paragraphs (a) and (c). The FAA issued policy memorandum ANM-03-115-28, dated October 2, 2003, and titled “Policy Statement on Use of Surrogate Parts When Evaluating

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43 Seatbacks and Seatback Mounted Accessories for Compliance with §§ 25.562(c) (5) and

25.785(b) and (d). This policy may be used with any test method used to demonstrate compliance with blunt force trauma for items mounted on the seatback. The policy is applicable to Amendment 25-0, for §§ 25.785 (a) and (c) as follows: (Amendment 25-0)

(i) In many row-to-row seat configurations, seatback mounted accessories are installed within the head paths of forward facing seated occupants. In order to demonstrate compliance with the aforementioned requirements, tests are conducted to assess the injury potential of these seatbacks and accessories. This policy only addresses head injury caused by blunt trauma. It does not address parts that become loose or sharp projections that are formed that may be injurious to a seated occupant during a head impact. (Amendment 25-0)

(ii) The types of tests that are conducted for blunt trauma assessments are dependant on the certification basis of the airplane. Typically, airplanes which do not have § 25.562(c)(5) in their certification basis, must still comply with the more general occupant protection requirements of §§ 25.785(a) and (c). Sections 25.785(a) and (c) require that a seat be designed so that an occupant would not suffer “serious injury” in an emergency landing and that injurious objects within the striking radius of the head be eliminated. As a result, seatbacks/accessories on these airplanes must be evaluated to ensure that an occupant would not suffer serious head injury from blunt trauma. (Amendment 25-0)

(iii) Currently, blunt trauma tests are conducted with seatback mounted accessories represented by actual production parts or parts that are similar in construction to the production parts. Industry has informed the FAA that certification delays occur due to the unavailability of actual accessories for testing. In addition, accessories are typically damaged during certification tests and are not usable in subsequent tests or for installation and delivery to a customer. Several specimens of the same part are repeatedly used, and damaged, during certification tests due to test failures or substantiating alternate seatback designs. This results in significant costs to manufacturers and customers. (Amendment 25-0)

(iv) The FAA has determined that it is acceptable to use a surrogate test article made of 6061-T4 aluminum which meets the criteria below in lieu of an accessory for demonstrating compliance with §§ 25.785(a) and (c) for blunt trauma assessments. An exception to the use of the surrogate test article occurs when the accessory is more rigid (deflects less and absorbs less energy during impact) than the plate defined in this AC. In that case, the accessory should be used in the test(s) and not a surrogate test article. The following criteria are applicable when using a surrogate test article during blunt trauma testing in accordance with §§ 25. 785(a) and (c): (Amendment 25-0) (A) The surrogate part should be fabricated from 6061-T4 aluminum and have a minimum thickness of 0.238-inch (i.e., 0.25-inch minus a 0.012-inch manufacturing tolerance) at all locations. The length and width of the surrogate part should equal, within tolerances, the length and width of the actual part, respectively. (Amendment 25-0) (B) The exposed surface of the surrogate part that will be impacted should be flat. That is, it is not required to have the contour of the accessory’s exposed surface represented

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44 by the surrogate part. Note that this is based on typical accessory installations which are essentially mounted flush with the seatback and have a generally homogeneous contact area.

Small variations in the surface due to the contour of plastic parts may be ignored. Designs that differ from this (e.g., a design with an exposed structural protrusion) might require the exposed surface of the actual part to be represented in order to adequately assess head injury potential.

(Amendment 25-0) (C) The weight of the surrogate part, and additional ballast if needed, should be ±10 percent of the weight of the actual part. (Amendment 25-0) (D) The surrogate part should be located on the seatback in the same place

(i.e., within manufacturing tolerances for mounting the actual part) where the actual part would be located in terms of the x and y coordinates in Figure 81-1. The surrogate part should be located such that the surface, which will be contacted during the test, is at the same location (i.e., within manufacturing tolerances for mounting the actual part) where the actual part would be in terms of the z coordinate (refer to figure 81-1). (Amendment 25-0) (E) The surrogate part should be attached to the seat by the final production hardware or a conservative representation of the final production hardware. For substantiating blunt trauma requirements, a conservative representation of the attachment hardware would be at least as rigid as the actual hardware. The surrogate part should be mounted so that it would not move farther or faster, with respect to the seatback, than the actual part during the test.

(Amendment 25-0) (F) If the surrogate part cracks during a test, the test results are invalid.

(Amendment 25-0) (G) A surrogate part made of a material and thickness other than 6061-T4 aluminum in a nominal thickness of 0.25-inch may be used if an FAA Aircraft Certification Office finds that it is at least as rigid (i.e., it deflects less and absorbs less energy during the test).

Surrogate test articles which are less rigid than the aluminum surrogate part defined above are not addressed in this AC. If an applicant desires to use a surrogate part which is less rigid, its use should be approved through the issue paper process (or equivalent) or by an FAA policy memorandum. Testing may be required to determine the acceptability of these less rigid surrogate parts. (Amendment 25-0)

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FIGURE 81-1 SURROGATE PART INSTALLED ON SEATBACK Surrogate part installed on the back side of the seatback in lieu of the actual accessory.

The x and y axes are in the plane of the backside of the seatback 45

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(3) Paragraphs (a) and (c). The FAA issued policy memorandum ANM-03-115-31, dated May 9, 2005, and titled “Policy Statement on Conducting Component Level Tests to Demonstrate Compliance with §§ 25.785(b) and (d).” Appendix 13 of this AC contains the complete policy memorandum. Applicants may use the test methods described in Appendix 13 to demonstrate compliance with §§ 25.785(a) and (c) for both blunt force trauma and formation of post-impact sharp or injurious edges or features for items within the head strike zone defined in figure 81-2. The policy is applicable to design certification projects whose certification basis includes Amendment 25-0, for §§ 25.785 (a) and (c). (Amendment 25-0)

(4) Paragraph (c). For side facing seat installations, the following are satisfactory and do not need a shoulder harness: (Amendment 25-0)

(i) An unpadded bulkhead immediately adjacent to and forward of a normal width armrest. (Amendment 25-0)

(ii) Another occupant who serves as a “human cushion.” (Amendment 25-0)

(5) Paragraph (c)(2). The striking radius of the head for a forward facing seat (head strike zone) is considered to be a zone whose length is bounded between an arc at the shoulder height of the 5th percentile female occupant (20.5-inches) and an arc at the limit of the head path (35-inches) whose centers are at the intersection of the plane of the uncompressed top of the seat bottom cushion with the plane of the uncompressed front of the back cushion; commonly referred to as the cushion reference point (CRP), as shown in figure 81-2. Previously this was referred to as seat reference point (SRP). However, with the advent of dynamic seat testing, the definition for SRP was changed (refer to SAE ARP5526D). The head strike zone extends in the direction parallel to the airplane longitudinal axis. The width of the head strike zone is bounded by a vertical plane through the intersection of the centerlines of each armrest and the CRP as shown in figure 81-2. Typical installations to be considered are bulkheads, cabinets, tables, and passenger evacuation slide covers. The installation should not contain any pointed corners or sharp edges. The testing used to demonstrate that the installation is not injurious must take into account whether the system (e.g., seatback mounted telephone) is allowed to be used during taxi, takeoff and landing. If the system is allowed to be used during these phases of operation, the testing must consider the system in both the deployed and stowed position (e.g., seatback mounted telephone in or out of the cradle). If a surface or interior feature is located such that it is potentially hazardous in a combination of forward and side loads, it should be substantiated even if it might be slightly outside of the head strike zone. Any surface less than 18-inches above the floor need not be considered. Surfaces within the head strike zone may be padded with energy absorbing material, such as one inch of either Ensolite (Type AH, AHC, IV3, HHC or HH), Klegecell, or Airex 4070. Foam rubber is not satisfactory since it is an energy storing material. If the padding is easily removed, there should be acceptable placarding requiring the padding be in place during taxi, takeoff, and landing. (Amendment 25-0)

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97/52/50 АС 25-17A Change 1 FIGURE 81-2 HEAD STRIKE ZONE FOR § 25.785 Head Strike Zone

20.5 inch 35 inch arc arc

- CRP 18 inches CRP Centerline 35 inch arc of Armrest Seat Axis Airplane Longitudinal Axis Centerline of Armrest Seat Axis ‚CRP Airplane Centerline Longitudinal Axis of Armrest 35 inch arc Centerline of Armrest 47

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(6) Paragraph (c)(2). A flat surface within the 35-inch head strike arc, such as a table or partition, may be tested to the criteria of Society of Automotive Engineers (SAE) J921 or the following criteria. Impact injury criteria is discussed in AC 21-22, Injury Criteria for Human Exposure to Impact. (Amendment 25-0)

(i) A 13-pound bowling ball may be used to simulate the head of a 170-pound person whose seat belt is fastened and is subjected to 9g. (Amendment 25-0)

(ii) The ball shall impact the surface with at least 2780-inch-pounds of energy.

(Amendment 25-0)

(iii) The attachments of the test article shall not fail completely. (Amendment 25-0)

(iv) No parts shall become loose or sharp projections be formed that would be hazardous to the passengers. (Amendment 25-0)

(v) The test article may deform locally. (Amendment 25-0)

(vi) The surface being tested should perform equal to or better than a previously approved surface. The intent of this comparative test method is to test similar items (e.g., a seatback that does not have a telephone with a seatback that has a telephone installed). This test method should not be used to compare a seatback to an armrest. (Amendment 25-0)

(7) Paragraph (c)(2).

(i) Some passenger seats are designed with armrests that pivot upward such that the armrest could protrude beyond the seatbacks resulting in a potentially hazardous condition to persons seated behind these seats. Armrests that are adequately delethalized or restricted such that they cannot protrude aft of either seatback in any position are acceptable. (Amendment 25-0)

(ii) Armrests that are offset can be within the headstrike path of an occupant to the rear. Armrests within the striking radius of the head that are:

(A) bounded on both sides of the armrest by the seat backs and are offset more than 2-inches from the armrests of the seat to the rear, or (B) forward of an additional (exposed) seat in the row behind it, such that the forward armrest is bounded on one side only are considered to be injurious objects. The head must be protected from these injurious objects by some additional means such as padding.

Armrests that are bounded only on one side and not offset from the armrest of the seat in the rear are not considered to be injurious objects. (Amendment 25-0)

(8) Paragraph (c)(2). The FAA issued policy memorandum 02-115-15, dated November 25, 2002, titled “New Policy with respect to compliance with § 25.785(d), Amendment 25-88, for certification of passenger seat armrests.” The policy in this

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49 memorandum may be used for demonstrating compliance with § 25.785(c)(2), Amendment 25-0, and is provided below. (Amendment 25-0)

(i) Armrests that might possibly be struck by persons seated behind (aft of) them are characterized as “bounded” or “unbounded.” Bounded armrests are defined as follows:

(A) An armrest that has a seatback on both sides, with the distance between the structure of the adjacent seatbacks no greater than five inches, or (B) An armrest that has a seatback on one side and the airplane sidewall panel or a wall that is part of an airplane furnishing (e.g., galley, closet, lavatory) on the other side with the distance between the structure of the seatback and the panel/wall no greater than five inches.

(ii) For purposes of this AC, the structure of the seatback is considered to be the parts of the seatback with load carrying capability. It does not include upholstery material or soft foam installed for occupant comfort. In some seat designs there is a metal frame in the seatback that forms the support structure to which the foam and upholstery are used to provide the shape of the seatback. When measuring the distance between the structure of the adjacent seatbacks of no greater than five inches, the measurement would be between these metal or composite supports structures.

(iii) Unbounded armrests are those that do not meet either definition above.

Additionally, seat places that are located aft of unbounded armrests may be characterized as either “exposed” or “non-exposed.” The non-exposed seat place is typically an aisle seat place,

i.e., located adjacent to a passenger aisle (refer to figure 81-3). The exposed seat place is typically located where the number of seats in the row forward is different from that of the seat row aft. For example, near Type III overwing exits, many airplanes have a double seat installed inboard of the exit with an empty space between the seat and the exit. The seat row aft of the double seat has a triple seat (refer to figure 81-4). In figure 81-4, seat place “A” is an exposed seat place that makes the outboard armrest of the double seat an unbounded exposed armrest.

(iv) The definitions above apply to all armrests in the airplane as applicable. The existing policy contained in this AC paragraphs 81b(5) and 81b(7) are still applicable to the armrests identified in the new policy below.

(A) Note: The policy below addresses armrests within the 35-inch head strike arc and surfaces 18-inches and greater above the floor. Armrests outside the 35-inch head strike arc and armrest surfaces less than 18-inches above the floor are acceptable as defined in this AC paragraphs 81b(5) and 81b(7).

(B) An armrest is acceptable by inspection if the armrests of two consecutive

(i.e., one aft of the other) seat assemblies (seats need not be of the same part number) are offset no greater 0.5-inch total, including design and production tolerances.

(C) Bounded armrests and non-exposed unbounded armrests are acceptable if:

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(1) The armrests of two consecutive seat assemblies are offset greater than 0.5-inch but no greater than five inches total, including design, and production tolerances, and

(2) The breakover feature of the seatback(s) adjacent to the armrest in the forward seat assembly is (are) locked out.

(D) The seatback breakover feature may be locked out by any method that requires a tool to release the lock out provision. The lockout of the breakover feature must be effective for the seatback in the upright position used for taxi, takeoff, and landing. Seatbacks incorporating an energy absorbing feature to meet the HIC requirements of § 25.562 are considered to have the breakover lockout and are acceptable. Whatever the method of seatback breakover lock out, there typically is some movement of the seatback. This movement of the seatback is acceptable as long as when the seatback is moved to the worst case position by a small hand load applied to the top of the seatback, the armrest is still afforded protection by the seatback, with the end of the top of the armrest being forward of the aft side of the seatback.

(E) Bounded armrests and non-exposed unbounded armrests, where the offset is greater than two (2)-inches total, including design and production tolerances, need to be addressed as being injurious objects within the striking radius of the head, e.g., by padding the armrest.

(F) Exposed unbounded armrests; if the armrests of two consecutive seat assemblies that are offset by more than 0.5-inch total, including design and production tolerances, need to be addressed as being injurious objects within the striking radius of the head,

e.g., by padding the armrest.

(G) Armrests that are padded (using appropriate padding material as described in paragraph 81b(5) of this AC) must have the padding cover the length of the armrest that is encompassed by 35-inch and smaller head strike arcs. Bounded armrests, where the seatback(s) have the breakover feature locked out, need not be padded to encompass the entire 35-inch head strike arc because the seatbacks prevent the contact of the armrest on the forward side of the seatback(s). Therefore, these armrests need only be padded to the forward edge of the seatback(s) in their upright position achieved after the small hand force is applied to the seatback. Portions of the armrest surface that cannot be contacted by the head are not required to be padded, e.g., the lower (or under) surface of a curved armrest.

(H) As an alternative to the use of padding, surfaces within the striking radius of the head that translate out of the striking radius under a nominal (10 pound) load may be considered to provide adequate protection, e.g., armrests that have been pivoted upward, which pivot downward out of the head strike arc under the nominal load. During an evaluation of this feature, the load must be applied in a direction that approximates the motion of a seated and belted occupant in the seat aft of the armrest under crash conditions.

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**51 FIGURE 81-3 ARMREST OFFSET**

**FIGURE 81-4 NON-EXPOSED AND EXPOSED ARMREST**

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(9) Paragraph (d). The seat back may serve as a firm hand hold. Since many seats are capable of breaking over, the breakover load must be adequate to be considered firm. A load of 25 lbs minimum, acting horizontally, is considered adequate when applied at the top center of the seat back. (Refer to paragraph 411b.(10) for maximum breakover force.) Very large seat pitches (in excess of 65-inches) may not permit the seatbacks to act as a handhold. This is due to both distance between the seatbacks and the capability of the seats to have very large amounts of recline. In this case, it may be necessary to install supplementary features to serve as handholds.

Seat mounted headrests that move relative to the seatback do not need to be assessed for their ability to provide a firm handhold, provided the seatback remains available for use as a handhold, and meets the criteria identified above. Other interior features such as class dividers, closets and other monuments may also serve as acceptable handholds if they provide a surface for occupants to push against to steady themselves while moving about the cabin interior.

(Amendment 25-0)

(10) Paragraph (f). Each berth installation should include a seat belt located approximately at the occupant's pelvis. For a berth installation with the feet facing forward, a bag, enclosing the legs to catch the upper torso when subjected to 9g, would be satisfactory in lieu of a padded end board. If the head is facing forward, a strap over each shoulder configuration would be satisfactory. If the berth is side facing, a padded side board or two belts, located approximately at the thighs and approximately at the chest, would be satisfactory.

(Amendment 25-0)

(11) Paragraph (h). Flight attendant seats that are provided for the airplane configuration should be installed near the approved floor level emergency exits. This should not be interpreted as a requirement to install flight attendant seats at each floor level exit. "Near" is defined in AC 25.785-1A. (Amendment 25-0)

(12) Paragraph (i). In order to reduce the deceleration "g" forces on occupants, some forward facing seats are designed to collapse. Usually, the design incorporates collapsible front legs. Such is acceptable if the collapse does not occur until a minimum of 8g has been applied.

After the collapse has occurred, the ultimate load of 9g should be applied and maintained for the required three seconds. The activation of the energy absorbing feature should not result in occupant injury. Various dimensions, such as 35-inches to injurious object clearance, aisle width and clearance, and interference with exits, should be evaluated before and after activation of the energy absorbing feature. Required dimensional clearances, such as aisles, passageways, flight attendant assist spaces, exit opening envelopes, and clearance between seats and potentially injurious surfaces must be maintained after the energy-absorbing feature is activated. The final position of the seat should not trap occupants. When testing a seat to demonstrate compliance with the static requirements of § 25.561, the testing should be conducted with an occupant center of gravity (CG) location as defined in NAS 809 (referenced in Technical Standard Order (TSO) C39) and AS8049 (referenced in the current version of TSO-C127). This CG location should be utilized in any airplane interface load analysis conducted. (Amendment 25-0)

(13) Paragraph (i). Technical Standard Order (TSO)-C22 is applicable only to seat belts. Technical Standard Order C114 may be applicable to shoulder harnesses, or they may be

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53 approved as part of the airplane. Sled tests with anthropomorphic dummies have shown that shoulder harness loads for forward facing seats can vary between 40 percent and 60 percent of the total load. Therefore, it is acceptable to substantiate a shoulder harness load of 60 percent (Refer to AC 25.785-1A, “Flight Attendant Seat and Torso Restraint System Installations,” dated 1/6/94): 0.6x9gx170 lbs = 918 lbs. If the seat belt is not approved under TSO-C22 or later revision, it should be approved as part of the airplane. The seat belt should be substantiated for 100 percent of the occupant load: 9g x 170 lbs = 1530 lbs. This is necessary even if the shoulder harness is permanently attached to the seat belt, since it is usually possible to utilize the seat belt without using the shoulder harness. The l.33 fitting factor is applicable to these configurations.

(Amendment 25-0)

(14) Paragraph (i)(1)(i). A seat is normally approved to TSO-C39 or later revision.

This approval may not account for the critical load when occupied by less than maximum occupants, e.g., one or two occupants in a triple seat. In some seat designs, occupancy by less than the maximum could be a critical design load for a particular structural member. All possible combinations of seat place occupancy should be substantiated by test or analysis. The loads for underseat baggage restraint systems attached to the seat should be added to seat loads.

Refer to § 25.787 guidance for underseat baggage criteria. This can be done by the TSO manufacturer when doing the TSO substantiation or by the applicant who is installing the seat.

(Amendment 25-0)

(15) Paragraph (i)(3). The l.33 factor is only required to be applied to the stated attachments. This factor should be applied to both ends of each attachment, (i.e., the seat end and the airplane end) and the fitting. If the applicant wishes to test the entire seat and belt assembly to this l.33 factor, it is satisfactory. (Amendment 25-0)

82. AMENDMENT 25-15, Effective October 24, 1967.

a. Regulation.

(a) Each seat, berth, safety belt, harness, and adjacent part of the airplane at each station designated as occupiable during takeoff and landing must be designed so that a person making proper use of these facilities will not suffer serious injury in an emergency landing as a result of the inertia forces specified in §§ 25.561.

(b) Each seat and berth must be approved.

[(c) Each occupant of a sideward facing seat must be protected from head injury by a safety belt and an energy absorbing rest that will support the arms, shoulders, head, and spine, or by a safety belt and a shoulder harness that will prevent the head from contacting any injurious object. Each occupant of any other seat must be protected from head injury by-

(1) A safety belt and shoulder harness that will prevent the head from contacting any injurious object;

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(2) A safety belt plus the elimination of any injurious object within striking radius of the head; or

(3) A safety belt and an energy absorbing rest that will support the arms, shoulders, head, and spine.]

(d) If the seat backs do not have a firm hand hold, there must be a hand grip or rail along each aisle to enable occupants to steady themselves while using the aisles in moderately rough air.

(e) Each projecting object that would injure persons seated or moving about the airplane in normal flight must be padded.

(f) Each berth must be designed so that the forward part has a padded end board, canvas diaphragm, or equivalent means, that can withstand the static load reaction of the occupant when subjected to the forward inertia force specified in § 25.561.

Berths must be free from corners and protuberances likely to cause serious injury to a person occupying the berth during emergency conditions.

(g) Each crewmember seat at flight deck stations must have provisions for a shoulder harness. These seats must meet the strength requirements of paragraph (i) of this section.

(h) Cabin attendant seats must be in the passenger compartment near approved floor level emergency exits.

(i) Each seat berth, and its supporting structure, must be designed for an occupant weight of 170 pounds, considering the maximum load factors, inertia forces, and reactions between the occupant, seat, and safety belt or harness, at each relevant flight and ground load condition (including the emergency landing conditions prescribed in § 25.561). For berths, the forward inertia force must be considered in accordance with paragraph (f) of this section and need not be considered with respect to the safety belt. In addition-

(1) The structural analysis and testing of the seats, berths, and their supporting structures may be determined by-

(i) Assuming that the critical load in the forward, sideward, downward, and rearward directions (as determined from the prescribed flight, ground, and emergency landing conditions) acts separately; and

(ii) Using selected combinations of loads if the required strength in each specified direction is substantiated;

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(2) Each pilot seat must be designed for the reactions resulting from the application of the pilot forces prescribed in § 25.395; and

(3) The inertia forces specified in § 25.561 must be multiplied by a factor of 1.33 (instead of the fitting factor prescribed in § 25.625) in determining the strength of the attachment of-

(i) Each seat to the structure; and

(ii) Each belt or harness to the seat or structure.

b. Guidance.

(l) Paragraph (a). In order for the seat belt to be effective, it should be positioned to lay across the hip bone and ideally be about 45 degrees from the horizontal. An acceptable range for this angle is 35 degrees to 55 degrees. An acceptable range for the shoulder harness is 30 degrees above to 5 degrees below the horizontal. Refer to ACs 25.785-1A, “Flight Attendant Seat and Torso Restraint System Installations,” dated 1/6/94, and 43.13-1A, “Acceptable Methods, Techniques, and Practices-Aircraft Inspection and Repair (with Errata Sheet),” dated 4/17/72, for related guidance. When testing a seat to demonstrate compliance with the static requirements of § 25.561, the testing should be conducted with an occupant center of gravity (CG) location as defined in NAS 809 (referenced in Technical Standard Order (TSO) C39) and AS8049 (referenced in the current version of TSO-C127). This CG location should be utilized in any airplane interface load analysis conducted. (Amendment 25-0)(2) Paragraphs (a) and (c).

The FAA issued policy memorandum ANM-03-115-28, dated October 2, 2003, and titled “Policy Statement on Use of Surrogate Parts When Evaluating Seatbacks and Seatback Mounted Accessories for Compliance with §§ 25.562(c) (5) and 25.785(b) and (d). This policy may be used with any test method used to demonstrate compliance with blunt force trauma for items mounted on the seatback. The policy is applicable to Amendment 25-15, for §§ 25.785 (a) and

(c) as follows: (Amendment 25-0)

(i) In many row-to-row seat configurations, seatback mounted accessories are installed within the head paths of forward facing seated occupants. In order to demonstrate compliance with the aforementioned requirements, tests are conducted to assess the injury potential of these seatbacks and accessories. This policy only addresses head injury caused by blunt trauma. It does not address parts that become loose or sharp projections that are formed that may be injurious to a seated occupant during a head impact.

(ii) The types of tests that are conducted for blunt trauma assessments are dependant on the certification basis of the airplane. Typically, airplanes which do not have § 25.562(c)(5) in their certification basis, must still comply with the more general occupant protection requirements of §§ 25.785(a) and (c). Sections 25.785(a) and (c) require that a seat be designed so that an occupant would not suffer “serious injury” in an emergency landing and that injurious objects within the striking radius of the head be eliminated. As a result,

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56 seatbacks/accessories on these airplanes must be evaluated to ensure that an occupant would not suffer serious head injury from blunt trauma.

(iii) Currently, blunt trauma tests are conducted with seatback mounted accessories represented by actual production parts or parts that are similar in construction to the production parts. Industry has informed the FAA that certification delays occur due to the unavailability of actual accessories for testing. In addition, accessories are typically damaged during certification tests and are not usable in subsequent tests or for installation and delivery to a customer. Several specimens of the same part are repeatedly used, and damaged, during certification tests due to test failures or substantiating alternate seatback designs. This results in significant costs to manufacturers and customers.

(iv) The FAA has determined that it is acceptable to use a surrogate test article made of 6061-T4 aluminum which meets the criteria below in lieu of an accessory for demonstrating compliance with §§ 25.785(a) and (c) for blunt trauma assessments. An exception to the use of the surrogate test article occurs when the accessory is more rigid (deflects less and absorbs less energy during impact) than the plate defined in this AC. In that case, the accessory should be used in the test(s) and not a surrogate test article. The following criteria are applicable when using a surrogate test article during blunt trauma testing in accordance with §§ 25. 785(a) and (c):

(A) The surrogate part should be fabricated from 6061-T4 aluminum and have a minimum thickness of 0.238-inch (i.e., 0.25-inch minus a 0.012-inch manufacturing tolerance) at all locations. The length and width of the surrogate part should equal, within tolerances, the length and width of the actual part, respectively.

(B) The exposed surface of the surrogate part that will be impacted should be flat. That is, it is not required to have the contour of the accessory’s exposed surface represented by the surrogate part. Note that this is based on typical accessory installations which are essentially mounted flush with the seatback and have a generally homogeneous contact area.

Small variations in the surface due to the contour of plastic parts may be ignored. Designs that differ from this (e.g., a design with an exposed structural protrusion) might require the exposed surface of the actual part to be represented in order to adequately assess head injury potential.

(C) The weight of the surrogate part, and additional ballast if needed, should be ±10 percent of the weight of the actual part.

(D) The surrogate part should be located on the seatback in the same place

(i.e., within manufacturing tolerances for mounting the actual part) where the actual part would be located in terms of the x and y coordinates in Figure 82-1. The surrogate part should be located such that the surface, which will be contacted during the test, is at the same location (i.e., within manufacturing tolerances for mounting the actual part) where the actual part would be in terms of the z coordinate (refer to figure 82-1).

(E) The surrogate part should be attached to the seat by the final production hardware or a conservative representation of the final production hardware. For substantiating

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57 blunt trauma requirements, a conservative representation of the attachment hardware would be at least as rigid as the actual hardware. The surrogate part should be mounted so that it would not move farther or faster, with respect to the seatback, than the actual part during the test.

(F) If the surrogate part cracks during a test, the test results are invalid.

(G) A surrogate part made of a material and thickness other than 6061-T4 aluminum in a nominal thickness of 0.25-inch may be used if an FAA Aircraft Certification Office finds that it is at least as rigid (i.e., it deflects less and absorbs less energy during the test).

Surrogate test articles which are less rigid than the aluminum surrogate part defined above are not addressed in this AC. If an applicant desires to use a surrogate part which is less rigid, its use should be approved through the issue paper process (or equivalent) or by an FAA policy memorandum. Testing may be required to determine the acceptability of these less rigid surrogate parts.

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FIGURE 82-1 SURROGATE PART INSTALLED ON SEATBACK Surrogate part installed on the back side of the seatback in lieu of the actual accessory.

The x and y axes are in the plane of the backside of the seatback 58

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(3) Paragraphs (a) and (c). The FAA issued policy memorandum ANM-03-115-31, dated May 9, 2005, and titled “Policy Statement on Conducting Component Level Tests to Demonstrate Compliance with §§ 25.785(b) and (d).” Appendix 13 of this AC contains the complete policy memorandum. Applicants may use the test methods described in Appendix 13 to demonstrate compliance with §§ 25.785(a) and (c) for both blunt force trauma and formation of post-impact sharp or injurious edges or features for items within the head strike zone as defined in figure 82-2. The policy is applicable to design certification projects whose certification basis includes Amendment 25-15, for §§ 25.785 (a) and (c). (Amendment 25-0)

(4) Paragraph (c). For sideward facing seats, this change removed the option of a safety belt, and eliminated the possibility of locating any injurious object within striking radius of the head. This option is still satisfactory for forward and aft facing seats. The "human cushion" or unpadded bulkhead concept is not an adequate energy absorbing rest and therefore does not comply with this amendment of the regulation. The shoulder harness may be a diagonal shoulder harness over the forward shoulder. (Amendment 25-15)

(5) Paragraph (c)(2). The striking radius of the head for a forward facing seat (head strike zone) is considered to be a zone whose length is bounded between an arc at the shoulder height of the 5th percentile female occupant (20.5-inches) and an arc at the limit of the head path (35-inches) whose centers are at the intersection of the plane of the uncompressed top of the seat bottom cushion with the plane of the uncompressed front of the back cushion; commonly referred to as the cushion reference point (CRP), as shown in figure 82-2. Previously this was referred to as seat reference point (SRP). However, with the advent of dynamic seat testing, the definition for SRP was changed (refer to SAE ARP5526D). The head strike zone extends in the direction parallel to the airplane longitudinal axis. The width of the head strike zone is bounded by a vertical plane through the intersection of the centerlines of each armrest and the CRP as shown in figure 82-2. Typical installations to be considered are bulkheads, cabinets, tables, and passenger evacuation slide covers. The installation should not contain any pointed corners or sharp edges. The testing used to demonstrate that the installation is not injurious must take into account whether the system (e.g., seatback mounted telephone) is allowed to be used during taxi, takeoff and landing. If the system is allowed to be used during these phases of operation, the testing must consider the system in both the deployed and stowed position (e.g., seatback mounted telephone in or out of the cradle). If a surface or interior feature is located such that it is potentially hazardous in a combination of forward and side loads, it should be substantiated even if it might be slightly outside of the head strike zone. Any surface less than 18-inches above the floor need not be considered. Surfaces within the head strike zone may be padded with energy absorbing material, such as one inch of either Ensolite (Type AH, AHC, IV3, HHC or HH), Klegecell, or Airex 4070. Foam rubber is not satisfactory since it is an energy storing material. If the padding is easily removed, there should be acceptable placarding requiring the padding be in place during taxi, takeoff, and landing. (Amendment 25-0)

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FIGURE 82-2 HEAD STRIKE ZONE FOR § 25.785 Head Strike Zone

20.5 inch 35 inch arc arc CRP 18 inches CRP Centerline 35 inch arc of Armrest Seat Axis Airplane Longitudinal Axis Centerline of Armrest Seat Axis ‚CRP Airplane Centerline Longitudinal Axis of Armrest 35 inch arc Centerline of Armrest 60

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(6) Paragraph (c)(2). A flat surface within the 35-inch head strike arc, such as a table or partition, may be tested to the criteria of Society of Automotive Engineers (SAE) J921 or the following criteria. Impact injury criteria is discussed in AC 21-22, Injury Criteria for Human Exposure to Impact. (Amendment 25-0)

(i) A 13-pound bowling ball may be used to simulate the head of a 170-pound person whose seat belt is fastened and is subjected to 9g. (Amendment 25-0)

(ii) The ball shall impact the surface with at least 2780-inch-pounds of energy.

(Amendment 25-0)

(iii) The attachments of the test article shall not fail completely. (Amendment 25-0)

(iv) No parts shall become loose or sharp projections be formed that would be hazardous to the passengers. (Amendment 25-0)

(v) The test article may deform locally. (Amendment 25-0)

(vi) The surface being tested should perform equal to or better than a previously approved surface. The intent of this comparative test method is to test similar items (e.g., a seatback that does not have a telephone with a seatback that has a telephone installed). This test method should not be used to compare a seatback to an armrest. (Amendment 25-0)

(7) Paragraph (c)(2). (Amendment 25-0)

(i) Some passenger seats are designed with armrests that pivot upward such that the armrest could protrude beyond the seatbacks resulting in a potentially hazardous condition to persons seated behind these seats. Armrests that are adequately delethalized or restricted such that they cannot protrude aft of either seatback in any position are acceptable. (Amendment 25-0)

(ii) Armrests that are offset can be within the headstrike path of an occupant to the rear. Armrests within the striking radius of the head that are:

(A) bounded on both sides of the armrest by the seat backs and are offset more than 2-inches from the armrests of the seat to the rear, or (B) forward of an additional (exposed) seat in the row behind it, such that the forward armrest is bounded on one side only are considered to be injurious objects. The head must be protected from these injurious objects by some additional means such as padding.

Armrests that are bounded only on one side and not offset from the armrest of the seat in the rear are not considered to be injurious objects. (Amendment 25-0)

(8) Paragraph (c)(2). The FAA issued policy memorandum 02-115-15, dated November 25, 2002, titled “New Policy with respect to compliance with § 25.785(d), Amendment 25-88, for certification of passenger seat armrests.” The policy in this

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62 memorandum may be used for demonstrating compliance with § 25.785(c)(2), Amendment 25- 15, and is provided below. (Amendment 25-0)

(i) Armrests that might possibly be struck by persons seated behind (aft of) them are characterized as “bounded” or “unbounded.” Bounded armrests are defined as follows:

(A) An armrest that has a seatback on both sides, with the distance between the structure of the adjacent seatbacks no greater than five inches, or (B) An armrest that has a seatback on one side and the airplane sidewall panel or a wall that is part of an airplane furnishing (e.g., galley, closet, lavatory) on the other side with the distance between the structure of the seatback and the panel/wall no greater than five inches.

(ii) For purposes of this AC, the structure of the seatback is considered to be the parts of the seatback with load carrying capability. It does not include upholstery material or soft foam installed for occupant comfort. In some seat designs there is a metal frame in the seatback that forms the support structure to which the foam and upholstery are used to provide the shape of the seatback. When measuring the distance between the structure of the adjacent seatbacks of no greater than five inches, the measurement would be between these metal or composite supports structures.

(iii) Unbounded armrests are those that do not meet either definition above.

Additionally, seat places that are located aft of unbounded armrests may be characterized as either “exposed” or “non-exposed.” The non-exposed seat place is typically an aisle seat place,

i.e., located adjacent to a passenger aisle (refer to figure 82-3). The exposed seat place is typically located where the number of seats in the row forward is different from that of the seat row aft. For example, near Type III overwing exits, many airplanes have a double seat installed inboard of the exit with an empty space between the seat and the exit. The seat row aft of the double seat has a triple seat (refer to figure 82-4). In figure 82-4, seat place “A” is an exposed seat place that makes the outboard armrest of the double seat an unbounded exposed armrest.

(iv) The definitions above apply to all armrests in the airplane as applicable. The existing policy contained in this AC paragraphs 81b(5) and 81b(7) are still applicable to the armrests identified in the new policy below.

(A) Note: The policy below addresses armrests within the 35-inch head strike arc and surfaces 18-inches and greater above the floor. Armrests outside the 35-inch head strike arc and armrest surfaces less than 18-inches above the floor are acceptable as defined in this AC paragraphs 81b(5) and 81b(7).

(B) An armrest is acceptable by inspection if the armrests of two consecutive

(i.e., one aft of the other) seat assemblies (seats need not be of the same part number) are offset no greater 0.5-inch total, including design and production tolerances.

(C) Bounded armrests and non-exposed unbounded armrests are acceptable if:

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(1) The armrests of two consecutive seat assemblies are offset greater than 0.5-inch but no greater than two (2)-inches total, including design, and production tolerances, and

(2) The breakover feature of the seatback(s) adjacent to the armrest in the forward seat assembly is (are) locked out.

(D) The seatback breakover feature may be locked out by any method that requires a tool to release the lock out provision. The lockout of the breakover feature must be effective for the seatback in the upright position used for taxi, takeoff, and landing. Seatbacks incorporating an energy absorbing feature to meet the HIC requirements of § 25.562 are considered to have the breakover lockout and are acceptable. Whatever the method of seatback breakover lock out, there typically is some movement of the seatback. This movement of the seatback is acceptable as long as when the seatback is moved to the worst case position by a small hand load applied to the top of the seatback, the armrest is still afforded protection by the seatback, with the end of the top of the armrest being forward of the aft side of the seatback.

(E) Bounded armrests and non-exposed unbounded armrests, where the offset is greater than two (2)-inches total, including design and production tolerances, need to be addressed as being injurious objects within the striking radius of the head, e.g., by padding the armrest.

(F) Exposed unbounded armrests; if the armrests of two consecutive seat assemblies that are offset by more than 0.5-inch total, including design and production tolerances, need to be addressed as being injurious objects within the striking radius of the head,

e.g., by padding the armrest.

(G) Armrests that are padded (using appropriate padding material as described in paragraph 81b(5) of this AC) must have the padding cover the length of the armrest that is encompassed by 35-inch and smaller head strike arcs. Bounded armrests, where the seatback(s) have the breakover feature locked out, need not be padded to encompass the entire 35-inch head strike arc because the seatbacks prevent the contact of the armrest on the forward side of the seatback(s). Therefore, these armrests need only be padded to the forward edge of the seatback(s) in their upright position achieved after the small hand force is applied to the seatback. Portions of the armrest surface that cannot be contacted by the head are not required to be padded, e.g., the lower (or under) surface of a curved armrest.

(H) As an alternative to the use of padding, surfaces within the striking radius of the head that translate out of the striking radius under a nominal (10 pound) load may be considered to provide adequate protection, e.g., armrests that have been pivoted upward, which pivot downward out of the head strike arc under the nominal load. During an evaluation of this feature, the load must be applied in a direction that approximates the motion of a seated and belted occupant in the seat aft of the armrest under crash conditions.

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**64 FIGURE 82-3 ARMREST OFFSET**

**FIGURE 82-4 NON-EXPOSED AND EXPOSED ARMREST**

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(9) Paragraph (d). The seat back may serve as a firm hand hold. Since many seats are capable of breaking over, the breakover load must be adequate to be considered firm. A load of 25 lbs minimum, acting horizontally, is considered adequate when applied at the top center of the seat back. (Refer to paragraph 411b.(10) for maximum breakover force.) Very large seat pitches (in excess of 65-inches) may not permit the seatbacks to act as a handhold. This is due to both distance between the seatbacks and the capability of the seats to have very large amounts of recline. In this case, it may be necessary to install supplementary features to serve as handholds.

Seat mounted headrests that move relative to the seatback do not need to be assessed for their ability to provide a firm handhold, provided the seatback remains available for use as a handhold, and meets the criteria identified above. Other interior features such as class dividers, closets and other monuments may also serve as acceptable handholds if they provide a surface for occupants to push against to steady themselves while moving about the cabin interior.

(Amendment 25-0)

(10) Paragraph (f). Each berth installation should include a seat belt located approximately at the occupant's pelvis. For a berth installation with the feet facing forward, a bag, enclosing the legs to catch the upper torso when subjected to 9g, would be satisfactory in lieu of a padded end board. If the head is facing forward, a strap over each shoulder configuration would be satisfactory. If the berth is side facing, a padded side board or two belts, located approximately at the thighs and approximately at the chest, would be satisfactory.

(Amendment 25-0)

(11) Paragraph (h). Flight attendant seats that are provided for the airplane configuration should be installed near the approved floor level emergency exits. This should not be interpreted as a requirement to install flight attendant seats at each floor level exit. "Near" is defined in AC 25.785-A. (Amendment 25-0)

(12) Paragraph (i). In order to reduce the deceleration "g" forces on occupants, some forward facing seats are designed to collapse. Usually, the design incorporates collapsible front legs. Such is acceptable if the collapse does not occur until a minimum of 8g has been applied.

After the collapse has occurred, the ultimate load of 9g should be applied and maintained for the required three seconds. The activation of the energy absorbing feature should not result in occupant injury. Various dimensions, such as 35-inches to injurious object clearance, aisle width and clearance, and interference with exits, should be evaluated before and after activation of the energy absorbing feature. Required dimensional clearances, such as aisles, passageways, flight attendant assist spaces, exit opening envelopes, and clearance between seats and potentially injurious surfaces must be maintained after the energy-absorbing feature is activated. The final position of the seat should not trap occupants. When testing a seat to demonstrate compliance with the static requirements of § 25.561, the testing should be conducted with an occupant center of gravity (CG) location as defined in NAS 809 (referenced in Technical Standard Order (TSO) C39) and AS8049 (referenced in the current version of TSO-C127). This CG location should be utilized in any airplane interface load analysis conducted. (Amendment 25-0)

(13) Paragraph (i). Technical Standard Order (TSO)-C22 is applicable only to seat belts. Technical Standard Order C114 may be applicable to shoulder harnesses, or they may be

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66 approved as part of the airplane. Sled tests with anthropomorphic dummies have shown that shoulder harness loads for forward facing seats can vary between 40 percent and 60 percent of the total load. Therefore, it is acceptable to substantiate a shoulder harness load of 60 percent (Refer to AC 25.785-1A, “Flight Attendant Seat and Torso Restraint System Installations,” dated 1/6/94): 0.6x9gx170 lbs = 918 lbs. If the seat belt is not approved under TSO-C22 or later revision, it should be approved as part of the airplane. The seat belt should be substantiated for 100 percent of the occupant load: 9g x 170 lbs = 1530 lbs. This is necessary even if the shoulder harness is permanently attached to the seat belt, since it is usually possible to utilize the seat belt without using the shoulder harness. The l.33 fitting factor is applicable to these configurations.

(Amendment 25-0)

(14) Paragraph (i)(1)(i). A seat is normally approved to TSO-C39 or later revision.

This approval may not account for the critical load when occupied by less than maximum occupants, e.g., one or two occupants in a triple seat. In some seat designs, occupancy by less than the maximum could be a critical design load for a particular structural member. All possible combinations of seat place occupancy should be substantiated by test or analysis. The loads for underseat baggage restraint systems attached to the seat should be added to seat loads.

Refer to § 25.787 guidance for underseat baggage criteria. This can be done by the TSO manufacturer when doing the TSO substantiation or by the applicant who is installing the seat.

(Amendment 25-0)

(15) Paragraph (i)(3). The l.33 factor is only required to be applied to the stated attachments. This factor should be applied to both ends of each attachment, (i.e., the seat end and the airplane end) and the fitting. If the applicant wishes to test the entire seat and belt assembly to this l.33 factor, it is satisfactory. (Amendment 25-0)

83. AMENDMENT 25-20, Effective April 23, 1969.

a. Regulation.

(a) Each seat, berth, safety belt, harness, and adjacent part of the airplane at each station designated as occupiable during takeoff and landing must be designed so that a person making proper use of these facilities will not suffer serious injury in an emergency landing as a result of the inertia forces specified in §§ 25.561.

(b) Each seat and berth must be approved.

[(c) Each occupant of a seat that makes more than an 18 degree angle with the vertical plane containing the airplane centerline, must be protected from head injury by a safety belt and an energy absorbing rest that will support the arms, shoulders, head, and spine, or by a safety belt and shoulder harness that will prevent the head from contacting any injurious object.] Each occupant of any other seat must be protected from head injury by-

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(1) A safety belt and shoulder harness that will prevent the head from contacting any injurious object;

(2) A safety belt plus the elimination of any injurious object within striking radius of the head; or

(3) A safety belt and an energy absorbing rest that will support the arms, shoulders, head, and spine.

(d) If the seat backs do not have a firm hand hold, there must be a hand grip or rail along each aisle to enable occupants to steady themselves while using the aisles in moderately rough air.

(e) Each projecting object that would injure persons seated or moving about the airplane in normal flight must be padded.

(f) Each berth must be designed so that the forward part has a padded end board, canvas diaphragm, or equivalent means, that can withstand the static load reaction of the occupant when subjected to the forward inertia force specified in § 25.561.

Berths must be free from corners and protuberances likely to cause serious injury to a person occupying the berth during emergency conditions.

(g) Each crewmember seat at flight deck stations must have provisions for a shoulder harness. These seats must meet the strength requirements of paragraph (i) of this section.

(h) Cabin attendant seats must be in the passenger compartment near approved floor level emergency exits.

(i) Each seat berth, and its supporting structure, must be designed for an occupant weight of 170 pounds, considering the maximum load factors, inertia forces, and reactions between the occupant, seat, and safety belt or harness, at each relevant flight and ground load condition (including the emergency landing conditions prescribed in § 25.561). For berths, the forward inertia force must be considered in accordance with paragraph (f) of this section and need not be considered with respect to the safety belt. In addition-

(1) The structural analysis and testing of the seats, berths, and their supporting structures may be determined by-

(i) Assuming that the critical load in the forward, sideward, downward, and rearward directions (as determined from the prescribed flight, ground, and emergency landing conditions) acts separately; and

(ii) Using selected combinations of loads if the required strength in each specified direction is substantiated;

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(2) Each pilot seat must be designed for the reactions resulting from the application of the pilot forces prescribed in § 25.395; and

(3) The inertia forces specified in § 25.561 must be multiplied by a factor of 1.33 (instead of the fitting factor prescribed in § 25.625) in determining the strength of the attachment of-

(i) Each seat to the structure; and

(ii) Each belt or harness to the seat or structure.

b. Guidance.

(l) Paragraph (a). In order for the seat belt to be effective, it should be positioned to lay across the hip bone and ideally be about 45 degrees from the horizontal. An acceptable range for this angle is 35 degrees to 55 degrees. An acceptable range for the shoulder harness is 30 degrees above to 5 degrees below the horizontal. Refer to ACs 25.785-1A, “Flight Attendant Seat and Torso Restraint System Installations,” dated 1/6/94, and 43.13-1A, “Acceptable Methods, Techniques, and Practices-Aircraft Inspection and Repair (with Errata Sheet),” dated 4/17/72, for related guidance. When testing a seat to demonstrate compliance with the static requirements of § 25.561, the testing should be conducted with an occupant center of gravity (CG) location as defined in NAS 809 (referenced in Technical Standard Order (TSO) C39) and AS8049 (referenced in the current version of TSO-C127). This CG location should be utilized in any airplane interface load analysis conducted. (Amendment 25-0)

(2) Paragraphs (a) and (c). The FAA issued policy memorandum ANM-03-115-28, dated October 2, 2003, and titled “Policy Statement on Use of Surrogate Parts When Evaluating Seatbacks and Seatback Mounted Accessories for Compliance with §§ 25.562(c) (5) and

25.785(b) and (d). This policy may be used with any test method used to demonstrate compliance with blunt force trauma for items mounted on the seatback. The policy is applicable to Amendment 25-20, for §§ 25.785 (a) and (c) as follows: (Amendment 25-0)

(i) In many row-to-row seat configurations, seatback mounted accessories are installed within the head paths of forward facing seated occupants. In order to demonstrate compliance with the aforementioned requirements, tests are conducted to assess the injury potential of these seatbacks and accessories. This policy only addresses head injury caused by blunt trauma. It does not address parts that become loose or sharp projections that are formed that may be injurious to a seated occupant during a head impact.

(ii) The types of tests that are conducted for blunt trauma assessments are dependant on the certification basis of the airplane. Typically, airplanes which do not have § 25.562(c)(5) in their certification basis, must still comply with the more general occupant protection requirements of §§ 25.785(a) and (c). Sections 25.785(a) and (c) require that a seat be designed so that an occupant would not suffer “serious injury” in an emergency landing and that injurious objects within the striking radius of the head be eliminated. As a result,

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69 seatbacks/accessories on these airplanes must be evaluated to ensure that an occupant would not suffer serious head injury from blunt trauma.

(iii) Currently, blunt trauma tests are conducted with seatback mounted accessories represented by actual production parts or parts that are similar in construction to the production parts. Industry has informed the FAA that certification delays occur due to the unavailability of actual accessories for testing. In addition, accessories are typically damaged during certification tests and are not usable in subsequent tests or for installation and delivery to a customer. Several specimens of the same part are repeatedly used, and damaged, during certification tests due to test failures or substantiating alternate seatback designs. This results in significant costs to manufacturers and customers.

(iv) The FAA has determined that it is acceptable to use a surrogate test article made of 6061-T4 aluminum which meets the criteria below in lieu of an accessory for demonstrating compliance with §§ 25.785(a) and (c) for blunt trauma assessments. An exception to the use of the surrogate test article occurs when the accessory is more rigid (deflects less and absorbs less energy during impact) than the plate defined in this AC. In that case, the accessory should be used in the test(s) and not a surrogate test article. The following criteria are applicable when using a surrogate test article during blunt trauma testing in accordance with §§ 25. 785(a) and (c):

(A) The surrogate part should be fabricated from 6061-T4 aluminum and have a minimum thickness of 0.238-inch (i.e., 0.25-inch minus a 0.012-inch manufacturing tolerance) at all locations. The length and width of the surrogate part should equal, within tolerances, the length and width of the actual part, respectively.

(B) The exposed surface of the surrogate part that will be impacted should be flat. That is, it is not required to have the contour of the accessory’s exposed surface represented by the surrogate part. Note that this is based on typical accessory installations which are essentially mounted flush with the seatback and have a generally homogeneous contact area.

Small variations in the surface due to the contour of plastic parts may be ignored. Designs that differ from this (e.g., a design with an exposed structural protrusion) might require the exposed surface of the actual part to be represented in order to adequately assess head injury potential.

(C) The weight of the surrogate part, and additional ballast if needed, should be ±10 percent of the weight of the actual part.

(D) The surrogate part should be located on the seatback in the same place

(i.e., within manufacturing tolerances for mounting the actual part) where the actual part would be located in terms of the x and y coordinates in Figure 83-1. The surrogate part should be located such that the surface, which will be contacted during the test, is at the same location (i.e., within manufacturing tolerances for mounting the actual part) where the actual part would be in terms of the z coordinate (refer to figure 83-1).

(E) The surrogate part should be attached to the seat by the final production hardware or a conservative representation of the final production hardware. For substantiating

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70 blunt trauma requirements, a conservative representation of the attachment hardware would be at least as rigid as the actual hardware. The surrogate part should be mounted so that it would not move farther or faster, with respect to the seatback, than the actual part during the test.

(F) If the surrogate part cracks during a test, the test results are invalid.

(G) A surrogate part made of a material and thickness other than 6061-T4 aluminum in a nominal thickness of 0.25-inch may be used if an FAA Aircraft Certification Office finds that it is at least as rigid (i.e., it deflects less and absorbs less energy during the test).

Surrogate test articles which are less rigid than the aluminum surrogate part defined above are not addressed in this AC. If an applicant desires to use a surrogate part which is less rigid, its use should be approved through the issue paper process (or equivalent) or by an FAA policy memorandum. Testing may be required to determine the acceptability of these less rigid surrogate parts.

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FIGURE 83-1 SURROGATE PART INSTALLED ON SEATBACK Surrogate part installed on the back side of the seatback in lieu of the actual accessory.

The x and y axes are in the plane of the backside of the seatback 71

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(3) Paragraphs (a) and (c). The FAA issued policy memorandum ANM-03-115-31, dated May 9, 2005, and titled “Policy Statement on Conducting Component Level Tests to Demonstrate Compliance with §§ 25.785(b) and (d).” Appendix 13 of this AC contains the complete policy memorandum. Applicants may use the test methods in Appendix 13 to to demonstrate compliance with §§ 25.785(a) and (c) for both blunt force trauma and formation of post-impact sharp or injurious edges or features for items within the head strike zone as defined in figure 83-2. The policy is applicable to design certification projects whose certification basis includes Amendment 25-20, for §§ 25.785 (a) and (c). (Amendment 25-0)

(4) Paragraph (c). For sideward facing seats, this change removed the option of a safety belt, and eliminated the possibility of locating any injurious object within striking radius of the head. This option is still satisfactory for forward and aft facing seats. The "human cushion" or unpadded bulkhead concept is not an adequate energy absorbing rest and therefore does not comply with this amendment of the regulation. The shoulder harness may be a diagonal shoulder harness over the forward shoulder. (Amendment 25-15)

(5) Paragraph (c). The 18-degree requirement applies to both forward and aft facing seat installations. If the forward direction is considered as 0 degrees or 360 degrees of a circle, the segments from 18 degrees to 162 degrees and 198 degrees to 342 degrees are considered a side facing seat and the seat installation must comply with one of the two options stated in the regulation. (Amendment 25-20)

(6) Paragraph (c)(2). The striking radius of the head for a forward facing seat (head strike zone) is considered to be a zone whose length is bounded between an arc at the shoulder height of the 5th percentile female occupant (20.5-inches) and an arc at the limit of the head path (35-inches) whose centers are at the intersection of the plane of the uncompressed top of the seat bottom cushion with the plane of the uncompressed front of the back cushion; commonly referred to as the cushion reference point (CRP), as shown in figure 83-2. Previously this was referred to as seat reference point (SRP). However, with the advent of dynamic seat testing the definition for SRP was changed (refer to SAE ARP6626D). The head strike zone extends in the direction parallel to the airplane longitudinal axis. The width of the head strike zone is bounded by a vertical plane through the intersection of the centerlines of each armrest and the CRP as shown in figure 83-2. Typical installations to be considered are bulkheads, cabinets, tables, and passenger evacuation slide covers. The installation should not contain any pointed corners or sharp edges. The testing used to demonstrate that the installation is not injurious must take into account whether the system (e.g., seatback mounted telephone) is allowed to be used during taxi, takeoff and landing. If the system is allowed to be used during these phases of operation, the testing must consider the system in both the deployed and stowed position (e.g., seatback mounted telephone in or out of the cradle). If a surface or interior feature is located such that it is potentially hazardous in a combination of forward and side loads, it should be substantiated even if it might be slightly outside of the head strike zone. Any surface less than 18-inches above the floor need not be considered. Surfaces within the head strike zone may be padded with energy absorbing material, such as one inch of either Ensolite (Type AH, AHC, IV3, HHC or HH), Klegecell, or Airex 4070. Foam rubber is not satisfactory since it is an energy storing material. If the padding is easily removed, there should be acceptable placarding requiring the padding be in place during taxi, takeoff, and landing. (Amendment 25-0)

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FIGURE 83-2 HEAD STRIKE ZONE FOR § 25.785 Head Strike Zone

20.5 inch 35 inch arc arc CRP 18 inches CRP Centerline 35 inch arc of Armrest Seat Axis Airplane Longitudinal Axis Centerline of Armrest Seat Axis ‚CRP Airplane Centerline Longitudinal Axis of Armrest 35 inch arc Centerline of Armrest 73

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(7) Paragraph (c)(2). A flat surface within the 35-inch head strike arc, such as a table or partition, may be tested to the criteria of Society of Automotive Engineers (SAE) J921 or the following criteria. Impact injury criteria is discussed in AC 21-22, Injury Criteria for Human Exposure to Impact. (Amendment 25-0)

(i) A 13-pound bowling ball may be used to simulate the head of a 170-pound person whose seat belt is fastened and is subjected to 9g. (Amendment 25-0)

(ii) The ball shall impact the surface with at least 2780-inch-pounds of energy.

(Amendment 25-0)

(iii) The attachments of the test article shall not fail completely. (Amendment 25-0)

(iv) No parts shall become loose or sharp projections be formed that would be hazardous to the passengers. (Amendment 25-0)

(v) The test article may deform locally. (Amendment 25-0)

(vi) The surface being tested should perform equal to or better than a previously approved surface. The intent of this comparative test method is to test similar items (e.g., a seatback that does not have a telephone with a seatback that has a telephone installed). This test method should not be used to compare a seatback to an armrest. (Amendment 25-0)

(8) Paragraph (c)(2). (Amendment 25-0)

(i) Some passenger seats are designed with armrests that pivot upward such that the armrest could protrude beyond the seatbacks resulting in a potentially hazardous condition to persons seated behind these seats. Armrests that are adequately delethalized or restricted such that they cannot protrude aft of either seatback in any position are acceptable. (Amendment 25-0)

(ii) Armrests that are offset can be within the headstrike path of an occupant to the rear. Armrests within the striking radius of the head that are:

(A) bounded on both sides of the armrest by the seat backs and are offset more than 2-inches from the armrests of the seat to the rear, or (B) forward of an additional (exposed) seat in the row behind it, such that the forward armrest is bounded on one side only are considered to be injurious objects. The head must be protected from these injurious objects by some additional means such as padding.

Armrests that are bounded only on one side and not offset from the armrest of the seat in the rear are not considered to be injurious objects. (Amendment 25-0)

(9) Paragraph (c)(2). The FAA issued policy memorandum 02-115-15, dated November 25, 2002, titled “New Policy with respect to compliance with § 25.785(d), Amendment 25-88, for certification of passenger seat armrests.” The policy in this

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75 memorandum may be used for demonstrating compliance with § 25.785(c)(2), Amendment 25- 20, and is provided below. (Amendment 25-0)

(i) Armrests that might possibly be struck by persons seated behind (aft of) them are characterized as “bounded” or “unbounded.” Bounded armrests are defined as follows:

(A) An armrest that has a seatback on both sides, with the distance between the structure of the adjacent seatbacks no greater than five inches, or (B) An armrest that has a seatback on one side and the airplane sidewall panel or a wall that is part of an airplane furnishing (e.g., galley, closet, lavatory) on the other side with the distance between the structure of the seatback and the panel/wall no greater than five inches.

(ii) For purposes of this AC, the structure of the seatback is considered to be the parts of the seatback with load carrying capability. It does not include upholstery material or soft foam installed for occupant comfort. In some seat designs there is a metal frame in the seatback that forms the support structure to which the foam and upholstery are used to provide the shape of the seatback. When measuring the distance between the structure of the adjacent seatbacks of no greater than five inches, the measurement would be between these metal or composite supports structures.

(iii) Unbounded armrests are those that do not meet either definition above.

Additionally, seat places that are located aft of unbounded armrests may be characterized as either “exposed” or “non-exposed.” The non-exposed seat place is typically an aisle seat place,

i.e., located adjacent to a passenger aisle (refer to figure 83-3). The exposed seat place is typically located where the number of seats in the row forward is different from that of the seat row aft. For example, near Type III overwing exits, many airplanes have a double seat installed inboard of the exit with an empty space between the seat and the exit. The seat row aft of the double seat has a triple seat (refer to figure 83-4). In figure 83-4, seat place “A” is an exposed seat place that makes the outboard armrest of the double seat an unbounded exposed armrest.

(iv) The definitions above apply to all armrests in the airplane as applicable. The existing policy contained in this AC paragraphs 81b(5) and 81b(7) are still applicable to the armrests identified in the new policy below.

(A) Note: The policy below addresses armrests within the 35-inch head strike arc and surfaces 18-inches and greater above the floor. Armrests outside the 35-inch head strike arc and armrest surfaces less than 18-inches above the floor are acceptable as defined in this AC paragraphs 81b(5) and 81b(7).

(B) An armrest is acceptable by inspection if the armrests of two consecutive

(i.e., one aft of the other) seat assemblies (seats need not be of the same part number) are offset no greater 0.5-inch total, including design and production tolerances.

(C) Bounded armrests and non-exposed unbounded armrests are acceptable if:

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(1) The armrests of two consecutive seat assemblies are offset greater than 0.5-inch but no greater than two (2)-inches total, including design, and production tolerances, and

(2) The breakover feature of the seatback(s) adjacent to the armrest in the forward seat assembly is (are) locked out.

(D) The seatback breakover feature may be locked out by any method that requires a tool to release the lock out provision. The lockout of the breakover feature must be effective for the seatback in the upright position used for taxi, takeoff, and landing. Seatbacks incorporating an energy absorbing feature to meet the HIC requirements of § 25.562 are considered to have the breakover lockout and are acceptable. Whatever the method of seatback breakover lock out, there typically is some movement of the seatback. This movement of the seatback is acceptable as long as when the seatback is moved to the worst case position by a small hand load applied to the top of the seatback, the armrest is still afforded protection by the seatback, with the end of the top of the armrest being forward of the aft side of the seatback.

(E) Bounded armrests and non-exposed unbounded armrests, where the offset is greater than two (2)-inches total, including design and production tolerances, need to be addressed as being injurious objects within the striking radius of the head, e.g., by padding the armrest.

(F) Exposed unbounded armrests; if the armrests of two consecutive seat assemblies that are offset by more than 0.5-inch total, including design and production tolerances, need to be addressed as being injurious objects within the striking radius of the head,

e.g., by padding the armrest.

(G) Armrests that are padded (using appropriate padding material as described in paragraph 81b(5) of this AC) must have the padding cover the length of the armrest that is encompassed by 35-inch and smaller head strike arcs. Bounded armrests, where the seatback(s) have the breakover feature locked out, need not be padded to encompass the entire 35-inch head strike arc because the seatbacks prevent the contact of the armrest on the forward side of the seatback(s). Therefore, these armrests need only be padded to the forward edge of the seatback(s) in their upright position achieved after the small hand force is applied to the seatback. Portions of the armrest surface that cannot be contacted by the head are not required to be padded, e.g., the lower (or under) surface of a curved armrest.

(H) As an alternative to the use of padding, surfaces within the striking radius of the head that translate out of the striking radius under a nominal (10 pound) load may be considered to provide adequate protection, e.g., armrests that have been pivoted upward, which pivot downward out of the head strike arc under the nominal load. During an evaluation of this feature, the load must be applied in a direction that approximates the motion of a seated and belted occupant in the seat aft of the armrest under crash conditions.

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**77 FIGURE 83-3 ARMREST OFFSET**

**FIGURE 83-4 NON-EXPOSED AND EXPOSED ARMREST**

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(10) Paragraph (d). The seat back may serve as a firm hand hold. Since many seats are capable of breaking over, the breakover load must be adequate to be considered firm. A load of 25 lbs minimum, acting horizontally, is considered adequate when applied at the top center of the seat back. (Refer to paragraph 411b.(10) for maximum breakover force.) Very large seat pitches (in excess of 65-inches) may not permit the seatbacks to act as a handhold. This is due to both distance between the seatbacks and the capability of the seats to have very large amounts of recline. In this case, it may be necessary to install supplementary features to serve as handholds.

Seat mounted headrests that move relative to the seatback do not need to be assessed for their ability to provide a firm handhold, provided the seatback remains available for use as a handhold, and meets the criteria identified above. Other interior features such as class dividers, closets and other monuments may also serve as acceptable handholds if they provide a surface for occupants to push against to steady themselves while moving about the cabin interior.

(Amendment 25-0)

(11) Paragraph (f). Each berth installation should include a seat belt located approximately at the occupant's pelvis. For a berth installation with the feet facing forward, a bag, enclosing the legs to catch the upper torso when subjected to 9g, would be satisfactory in lieu of a padded end board. If the head is facing forward, a strap over each shoulder configuration would be satisfactory. If the berth is side facing, a padded side board or two belts, located approximately at the thighs and approximately at the chest, would be satisfactory.

(Amendment 25-0)

(12) Paragraph (h). Flight attendant seats that are provided for the airplane configuration should be installed near the approved floor level emergency exits. This should not be interpreted as a requirement to install flight attendant seats at each floor level exit. "Near" is defined in AC 25.785-1A. (Amendment 25-0)

(13) Paragraph (i). In order to reduce the deceleration "g" forces on occupants, some forward facing seats are designed to collapse. Usually, the design incorporates collapsible front legs. Such is acceptable if the collapse does not occur until a minimum of 8g has been applied.

After the collapse has occurred, the ultimate load of 9g should be applied and maintained for the required three seconds. The activation of the energy absorbing feature should not result in occupant injury. Various dimensions, such as 35-inches to injurious object clearance, aisle width and clearance, and interference with exits, should be evaluated before and after activation of the energy absorbing feature. Required dimensional clearances, such as aisles, passageways, flight attendant assist spaces, exit opening envelopes, and clearance between seats and potentially injurious surfaces must be maintained after the energy-absorbing feature is activated. The final position of the seat should not trap occupants. When testing a seat to demonstrate compliance with the static requirements of § 25.561, the testing should be conducted with an occupant center of gravity (CG) location as defined in NAS 809 (referenced in Technical Standard Order (TSO) C39) and AS8049 (referenced in the current version of TSO-C127). This CG location should be utilized in any airplane interface load analysis conducted. (Amendment 25-0)

(14) Paragraph (i). Technical Standard Order (TSO)-C22 is applicable only to seat belts. Technical Standard Order C114 may be applicable to shoulder harnesses, or they may be

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79 approved as part of the airplane. Sled tests with anthropomorphic dummies have shown that shoulder harness loads for forward facing seats can vary between 40 percent and 60 percent of the total load. Therefore, it is acceptable to substantiate a shoulder harness load of 60 percent (Refer to AC 25.785-1A, “Flight Attendant Seat and Torso Restraint System Installations,” dated 1/6/94): 0.6x9gx170 lbs = 918 lbs. If the seat belt is not approved under TSO-C22 or later revision, it should be approved as part of the airplane. The seat belt should be substantiated for 100 percent of the occupant load: 9g x 170 lbs = 1530 lbs. This is necessary even if the shoulder harness is permanently attached to the seat belt, since it is usually possible to utilize the seat belt without using the shoulder harness. The l.33 fitting factor is applicable to these configurations.

(Amendment 25-0)

(15) Paragraph (i)(1)(i). A seat is normally approved to TSO-C39 or later revision.

This approval may not account for the critical load when occupied by less than maximum occupants, e.g., one or two occupants in a triple seat. In some seat designs, occupancy by less than the maximum could be a critical design load for a particular structural member. All possible combinations of seat place occupancy should be substantiated by test or analysis. The loads for underseat baggage restraint systems attached to the seat should be added to seat loads.

Refer to § 25.787 guidance for underseat baggage criteria. This can be done by the TSO manufacturer when doing the TSO substantiation or by the applicant who is installing the seat.

(Amendment 25-0)

(16) Paragraph (i)(3). The l.33 factor is only required to be applied to the stated attachments. This factor should be applied to both ends of each attachment, (i.e., the seat end and the airplane end) and the fitting. If the applicant wishes to test the entire seat and belt assembly to this l.33 factor, it is satisfactory. (Amendment 25-0)

84. AMENDMENT 25-32, Effective May 1, 1972.

a. Regulation.

(a) Each seat, berth, safety belt, harness, and adjacent part of the airplane at each station designated as occupiable during takeoff and landing must be designed so that a person making proper use of these facilities will not suffer serious injury in an emergency landing as a result of the inertia forces specified in §§ 25.561.

(b) Each seat and berth must be approved.

(c) Each occupant of a seat that makes more than an 18 degree angle with the vertical plane containing the airplane centerline, must be protected from head injury by a safety belt and an energy absorbing rest that will support the arms, shoulders, head, and spine, or by a safety belt and shoulder harness that will prevent the head from contacting any injurious object. [Each occupant of any other seat must be protected from head injury by a safety belt and, as appropriate to the type, location, and angle of facing of each seat, by one or more of the following:

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(1) A shoulder harness that will prevent the head from contacting any injurious object.

(2) The elimination of any injurious object within striking radius of the head.

(3) An energy absorbing rest that will support the arms, shoulders, head, and spine.]

(d) If the seat backs do not have a firm hand hold, there must be a hand grip or rail along each aisle to enable occupants to steady themselves while using the aisles in moderately rough air.

(e) Each projecting object that would injure persons seated or moving about the airplane in normal flight must be padded.

(f) Each berth must be designed so that the forward part has a padded end board, canvas diaphragm, or equivalent means, that can withstand the static load reaction of the occupant when subjected to the forward inertia force specified in § 25.561.

Berths must be free from corners and protuberances likely to cause serious injury to a person occupying the berth during emergency conditions.

(g) Each crewmember seat at flight deck stations must have provisions for a shoulder harness. These seats must meet the strength requirements of paragraph (i) of this section.

(h) Cabin attendant seats must be in the passenger compartment near approved floor level emergency exits.

(i) Each seat berth, and its supporting structure, must be designed for an occupant weight of 170 pounds, considering the maximum load factors, inertia forces, and reactions between the occupant, seat, and safety belt or harness, at each relevant flight and ground load condition (including the emergency landing conditions prescribed in § 25.561). For berths, the forward inertia force must be considered in accordance with paragraph (f) of this section and need not be considered with respect to the safety belt. In addition-

(1) The structural analysis and testing of the seats, berths, and their supporting structures may be determined by-

(i) Assuming that the critical load in the forward, sideward, downward, and rearward directions (as determined from the prescribed flight, ground, and emergency landing conditions) acts separately; and

(ii) Using selected combinations of loads if the required strength in each specified direction is substantiated;

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(2) Each pilot seat must be designed for the reactions resulting from the application of the pilot forces prescribed in § 25.395; and

(3) The inertia forces specified in § 25.561 must be multiplied by a factor of 1.33 (instead of the fitting factor prescribed in § 25.625) in determining the strength of the attachment of-

(i) Each seat to the structure; and

(ii) Each belt or harness to the seat or structure.

b. Guidance.

(l) Paragraph (a). In order for the seat belt to be effective, it should be positioned to lay across the hip bone and ideally be about 45 degrees from the horizontal. An acceptable range for this angle is 35 degrees to 55 degrees. An acceptable range for the shoulder harness is 30 degrees above to 5 degrees below the horizontal. Refer to ACs 25.785-1A, “Flight Attendant Seat and Torso Restraint System Installations,” dated 1/6/94, and 43.13-1A, “Acceptable Methods, Techniques, and Practices-Aircraft Inspection and Repair (with Errata Sheet),” dated 4/17/72, for related guidance. When testing a seat to demonstrate compliance with the static requirements of § 25.561, the testing should be conducted with an occupant center of gravity (CG) location as defined in NAS 809 (referenced in Technical Standard Order (TSO) C39) and AS8049 (referenced in the current version of TSO-C127). This CG location should be utilized in any airplane interface load analysis conducted. (Amendment 25-0)

(2) Paragraphs (a) and (c). The FAA issued policy memorandum ANM-03-115-28, dated October 2, 2003, and titled “Policy Statement on Use of Surrogate Parts When Evaluating Seatbacks and Seatback Mounted Accessories for Compliance with §§ 25.562(c) (5) and

25.785(b) and (d). This policy may be used with any test method used to demonstrate compliance with blunt force trauma for items mounted on the seatback. The policy is applicable to Amendment 25-32, for §§ 25.785 (a) and (c) as follows: (Amendment 25-0)

(i) In many row-to-row seat configurations, seatback mounted accessories are installed within the head paths of forward facing seated occupants. In order to demonstrate compliance with the aforementioned requirements, tests are conducted to assess the injury potential of these seatbacks and accessories. This policy only addresses head injury caused by blunt trauma. It does not address parts that become loose or sharp projections that are formed that may be injurious to a seated occupant during a head impact.

(ii) The types of tests that are conducted for blunt trauma assessments are dependant on the certification basis of the airplane. Typically, airplanes which do not have § 25.562(c)(5) in their certification basis, must still comply with the more general occupant protection requirements of §§ 25.785(a) and (c). Sections 25.785(a) and (c) require that a seat be designed so that an occupant would not suffer “serious injury” in an emergency landing and that injurious objects within the striking radius of the head be eliminated. As a result,

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82 seatbacks/accessories on these airplanes must be evaluated to ensure that an occupant would not suffer serious head injury from blunt trauma.

(iii) Currently, blunt trauma tests are conducted with seatback mounted accessories represented by actual production parts or parts that are similar in construction to the production parts. Industry has informed the FAA that certification delays occur due to the unavailability of actual accessories for testing. In addition, accessories are typically damaged during certification tests and are not usable in subsequent tests or for installation and delivery to a customer. Several specimens of the same part are repeatedly used, and damaged, during certification tests due to test failures or substantiating alternate seatback designs. This results in significant costs to manufacturers and customers.

(iv) The FAA has determined that it is acceptable to use a surrogate test article made of 6061-T4 aluminum which meets the criteria below in lieu of an accessory for demonstrating compliance with §§ 25.785(a) and (c) for blunt trauma assessments. An exception to the use of the surrogate test article occurs when the accessory is more rigid (deflects less and absorbs less energy during impact) than the plate defined in this AC. In that case, the accessory should be used in the test(s) and not a surrogate test article. The following criteria are applicable when using a surrogate test article during blunt trauma testing in accordance with §§ 25. 785(a) and (c):

(A) The surrogate part should be fabricated from 6061-T4 aluminum and have a minimum thickness of 0.238-inch (i.e., 0.25-inch minus a 0.012-inch manufacturing tolerance) at all locations. The length and width of the surrogate part should equal, within tolerances, the length and width of the actual part, respectively.

(B) The exposed surface of the surrogate part that will be impacted should be flat. That is, it is not required to have the contour of the accessory’s exposed surface represented by the surrogate part. Note that this is based on typical accessory installations which are essentially mounted flush with the seatback and have a generally homogeneous contact area.

Small variations in the surface due to the contour of plastic parts may be ignored. Designs that differ from this (e.g., a design with an exposed structural protrusion) might require the exposed surface of the actual part to be represented in order to adequately assess head injury potential.

(C) The weight of the surrogate part, and additional ballast if needed, should be ±10 percent of the weight of the actual part.

(D) The surrogate part should be located on the seatback in the same place

(i.e., within manufacturing tolerances for mounting the actual part) where the actual part would be located in terms of the x and y coordinates in Figure 84-1. The surrogate part should be located such that the surface, which will be contacted during the test, is at the same location (i.e., within manufacturing tolerances for mounting the actual part) where the actual part would be in terms of the z coordinate (refer to figure 84-1).

(E) The surrogate part should be attached to the seat by the final production hardware or a conservative representation of the final production hardware. For substantiating

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83 blunt trauma requirements, a conservative representation of the attachment hardware would be at least as rigid as the actual hardware. The surrogate part should be mounted so that it would not move farther or faster, with respect to the seatback, than the actual part during the test.

(F) If the surrogate part cracks during a test, the test results are invalid.

(G) A surrogate part made of a material and thickness other than 6061-T4 aluminum in a nominal thickness of 0.25-inch may be used if an FAA Aircraft Certification Office finds that it is at least as rigid (i.e., it deflects less and absorbs less energy during the test).

Surrogate test articles which are less rigid than the aluminum surrogate part defined above are not addressed in this AC. If an applicant desires to use a surrogate part which is less rigid, its use should be approved through the issue paper process (or equivalent) or by an FAA policy memorandum. Testing may be required to determine the acceptability of these less rigid surrogate parts.

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FIGURE 84-1 SURROGATE PART INSTALLED ON SEATBACK Surrogate part installed on the back side of the seatback in lieu of the actual accessory.

The x and y axes are in the plane of the backside of the seatback 84

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(3) Paragraphs (a) and (c). The FAA issued policy memorandum ANM-03-115-31, dated May 9, 2005, and titled “Policy Statement on Conducting Component Level Tests to Demonstrate Compliance with §§ 25.785(b) and (d).” Appendix 13 of this AC contains the complete policy memorandum. Applicants may use the test methods described in Appendix 13 to demonstrate compliance with §§ 25.785(a) and (c) for both blunt force trauma and formation of post-impact sharp or injurious edges or features for items within the head strike zone as defined in figure 84-2. The policy is applicable to design certification projects whose certification basis includes Amendment 25-32, for §§ 25.785 (a) and (c). (Amendment 25-0)

(4) Paragraph (c). For sideward facing seats, this change removed the option of a safety belt, and eliminated the possibility of locating any injurious object within striking radius of the head. This option is still satisfactory for forward and aft facing seats. The "human cushion" or unpadded bulkhead concept is not an adequate energy absorbing rest and therefore does not comply with this amendment of the regulation. The shoulder harness may be a diagonal shoulder harness over the forward shoulder. (Amendment 25-15)

(5) Paragraph (c). The 18-degree requirement applies to both forward and aft facing seat installations. If the forward direction is considered as 0 degrees or 360 degrees of a circle, the segments from 18 degrees to 162 degrees and 198 degrees to 342 degrees are considered a side facing seat and the seat installation must comply with one of the two options stated in the regulation. (Amendment 25-20)

(6) Paragraph (c)(2). The striking radius of the head for a forward facing seat (head strike zone) is considered to be a zone whose length is bounded between an arc at the shoulder height of the 5th percentile female occupant (20.5-inches) and an arc at the limit of the head path (35-inches) whose centers are at the intersection of the plane of the uncompressed top of the seat bottom cushion with the plane of the uncompressed front of the back cushion; commonly referred to as the cushion reference point (CRP), as shown in figure 84-2. Previously this was referred to as seat reference point (SRP). However, with the advent of dynamic seat testing the definition for SRP was changed (refer to SAE ARP5526D). The head strike zone extends in the direction parallel to the airplane longitudinal axis. The width of the head strike zone is bounded by a vertical plane through the intersection of the centerlines of each armrest and the CRP as shown in figure 84-2. Typical installations to be considered are bulkheads, cabinets, tables, and passenger evacuation slide covers. The installation should not contain any pointed corners or sharp edges. The testing used to demonstrate that the installation is not injurious must take into account whether the system (e.g., seatback mounted telephone) is allowed to be used during taxi, takeoff and landing. If the system is allowed to be used during these phases of operation, the testing must consider the system in both the deployed and stowed position (e.g., seatback mounted telephone in or out of the cradle). If a surface or interior feature is located such that it is potentially hazardous in a combination of forward and side loads, it should be substantiated even if it might be slightly outside of the head strike zone. Any surface less than 18-inches above the floor need not be considered. Surfaces within the head strike zone may be padded with energy absorbing material, such as one inch of either Ensolite (Type AH, AHC, IV3, HHC or HH), Klegecell, or Airex 4070. Foam rubber is not satisfactory since it is an energy storing material. If the padding is easily removed, there should be acceptable placarding requiring the padding be in place during taxi, takeoff, and landing. (Amendment 25-0)

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FIGURE 84-2 HEAD STRIKE ZONE FOR § 25.785 Head Strike Zone

20.5 inch 35 inch arc arc CRP 18 inches CRP Centerline 35 inch arc of Armrest Seat Axis Airplane Longitudinal Axis Centerline of Armrest Seat Axis ‚CRP Airplane Centerline Longitudinal Axis of Armrest 35 inch arc Centerline of Armrest 86

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(7) Paragraph (c)(2). A flat surface within the 35-inch head strike arc, such as a table or partition, may be tested to the criteria of Society of Automotive Engineers (SAE) J921 or the following criteria. Impact injury criteria is discussed in AC 21-22, Injury Criteria for Human Exposure to Impact. (Amendment 25-0)

(i) A 13-pound bowling ball may be used to simulate the head of a 170-pound person whose seat belt is fastened and is subjected to 9g. (Amendment 25-0)

(ii) The ball shall impact the surface with at least 2780-inch-pounds of energy.

(Amendment 25-0)

(iii) The attachments of the test article shall not fail completely. (Amendment 25-0)

(iv) No parts shall become loose or sharp projections be formed that would be hazardous to the passengers. (Amendment 25-0)

(v) The test article may deform locally. (Amendment 25-0)

(vi) The surface being tested should perform equal to or better than a previously approved surface. The intent of this comparative test method is to test similar items (e.g., a seatback that does not have a telephone with a seatback that has a telephone installed). This test method should not be used to compare a seatback to an armrest. (Amendment 25-0)

(8) Paragraph (c)(2). (Amendment 25-0)

(i) Some passenger seats are designed with armrests that pivot upward such that the armrest could protrude beyond the seatbacks resulting in a potentially hazardous condition to persons seated behind these seats. Armrests that are adequately delethalized or restricted such that they cannot protrude aft of either seatback in any position are acceptable. (Amendment 25-0)

(ii) Armrests that are offset can be within the headstrike path of an occupant to the rear. Armrests within the striking radius of the head that are:

(A) bounded on both sides of the armrest by the seat backs and are offset more than 2-inches from the armrests of the seat to the rear, or (B) forward of an additional (exposed) seat in the row behind it, such that the forward armrest is bounded on one side only are considered to be injurious objects. The head must be protected from these injurious objects by some additional means such as padding.

Armrests that are bounded only on one side and not offset from the armrest of the seat in the rear are not considered to be injurious objects. (Amendment 25-0)

(9) Paragraph (c)(2). The FAA issued policy memorandum 02-115-15, dated November 25, 2002, titled “New Policy with respect to compliance with § 25.785(d), Amendment 25-88, for certification of passenger seat armrests.” The policy in this

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88 memorandum may be used for demonstrating compliance with § 25.785(c)(2), Amendment 25- 32, and is provided below.

(i) Armrests that might possibly be struck by persons seated behind (aft of) them are characterized as “bounded” or “unbounded.” Bounded armrests are defined as follows:

(A) An armrest that has a seatback on both sides, with the distance between the structure of the adjacent seatbacks no greater than five inches, or (B) An armrest that has a seatback on one side and the airplane sidewall panel or a wall that is part of an airplane furnishing (e.g., galley, closet, lavatory) on the other side with the distance between the structure of the seatback and the panel/wall no greater than five inches.

(ii) For purposes of this AC, the structure of the seatback is considered to be the parts of the seatback with load carrying capability. It does not include upholstery material or soft foam installed for occupant comfort. In some seat designs there is a metal frame in the seatback that forms the support structure to which the foam and upholstery are used to provide the shape of the seatback. When measuring the distance between the structure of the adjacent seatbacks of no greater than five inches, the measurement would be between these metal or composite supports structures.

(iii) Unbounded armrests are those that do not meet either definition above.

Additionally, seat places that are located aft of unbounded armrests may be characterized as either “exposed” or “non-exposed.” The non-exposed seat place is typically an aisle seat place,

i.e., located adjacent to a passenger aisle (refer to figure 84-3). The exposed seat place is typically located where the number of seats in the row forward is different from that of the seat row aft. For example, near Type III overwing exits, many airplanes have a double seat installed inboard of the exit with an empty space between the seat and the exit. The seat row aft of the double seat has a triple seat (refer to figure 84-4). In figure 84-4, seat place “A” is an exposed seat place that makes the outboard armrest of the double seat an unbounded exposed armrest.

(iv) The definitions above apply to all armrests in the airplane as applicable. The existing policy contained in this AC paragraphs 81b(5) and 81b(7) are still applicable to the armrests identified in the new policy below.

(A) Note: The policy below addresses armrests within the 35-inch head strike arc and surfaces 18-inches and greater above the floor. Armrests outside the 35-inch head strike arc and armrest surfaces less than 18-inches above the floor are acceptable as defined in this AC paragraphs 81b(5) and 81b(7).

(B) An armrest is acceptable by inspection if the armrests of two consecutive

(i.e., one aft of the other) seat assemblies (seats need not be of the same part number) are offset no greater 0.5-inch total, including design and production tolerances.

(C) Bounded armrests and non-exposed unbounded armrests are acceptable if:

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(1) The armrests of two consecutive seat assemblies are offset greater than 0.5-inch but no greater than two (2)-inches total, including design, and production tolerances, and

(2) The breakover feature of the seatback(s) adjacent to the armrest in the forward seat assembly is (are) locked out.

(D) The seatback breakover feature may be locked out by any method that requires a tool to release the lock out provision. The lockout of the breakover feature must be effective for the seatback in the upright position used for taxi, takeoff, and landing. Seatbacks incorporating an energy absorbing feature to meet the HIC requirements of § 25.562 are considered to have the breakover lockout and are acceptable. Whatever the method of seatback breakover lock out, there typically is some movement of the seatback. This movement of the seatback is acceptable as long as when the seatback is moved to the worst case position by a small hand load applied to the top of the seatback, the armrest is still afforded protection by the seatback, with the end of the top of the armrest being forward of the aft side of the seatback.

(E) Bounded armrests and non-exposed unbounded armrests, where the offset is greater than two (2)-inches total, including design and production tolerances, need to be addressed as being injurious objects within the striking radius of the head, e.g., by padding the armrest.

(F) Exposed unbounded armrests; if the armrests of two consecutive seat assemblies that are offset by more than 0.5-inch total, including design and production tolerances, need to be addressed as being injurious objects within the striking radius of the head,

e.g., by padding the armrest.

(G) Armrests that are padded (using appropriate padding material as described in paragraph 81b(5) of this AC) must have the padding cover the length of the armrest that is encompassed by 35-inch and smaller head strike arcs. Bounded armrests, where the seatback(s) have the breakover feature locked out, need not be padded to encompass the entire 35-inch head strike arc because the seatbacks prevent the contact of the armrest on the forward side of the seatback(s). Therefore, these armrests need only be padded to the forward edge of the seatback(s) in their upright position achieved after the small hand force is applied to the seatback. Portions of the armrest surface that cannot be contacted by the head are not required to be padded, e.g., the lower (or under) surface of a curved armrest.

(H) As an alternative to the use of padding, surfaces within the striking radius of the head that translate out of the striking radius under a nominal (10 pound) load may be considered to provide adequate protection, e.g., armrests that have been pivoted upward, which pivot downward out of the head strike arc under the nominal load. During an evaluation of this feature, the load must be applied in a direction that approximates the motion of a seated and belted occupant in the seat aft of the armrest under crash conditions.

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**90 FIGURE 84-3 ARMREST OFFSET**

**FIGURE 84-4 NON-EXPOSED AND EXPOSED ARMREST**

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(10) Paragraph (d). The seat back may serve as a firm hand hold. Since many seats are capable of breaking over, the breakover load must be adequate to be considered firm. A load of 25 lbs minimum, acting horizontally, is considered adequate when applied at the top center of the seat back. (Refer to paragraph 411b.(10) for maximum breakover force.) Very large seat pitches (in excess of 65-inches) may not permit the seatbacks to act as a handhold. This is due to both distance between the seatbacks and the capability of the seats to have very large amounts of recline. In this case, it may be necessary to install supplementary features to serve as handholds.

Seat mounted headrests that move relative to the seatback do not need to be assessed for their ability to provide a firm handhold, provided the seatback remains available for use as a handhold, and meets the criteria identified above. Other interior features such as class dividers, closets and other monuments may also serve as acceptable handholds if they provide a surface for occupants to push against to steady themselves while moving about the cabin interior.

(Amendment 25-0)

(11) Paragraph (f). Each berth installation should include a seat belt located approximately at the occupant's pelvis. For a berth installation with the feet facing forward, a bag, enclosing the legs to catch the upper torso when subjected to 9g, would be satisfactory in lieu of a padded end board. If the head is facing forward, a strap over each shoulder configuration would be satisfactory. If the berth is side facing, a padded side board or two belts, located approximately at the thighs and approximately at the chest, would be satisfactory.

(Amendment 25-0)

(12) Paragraph (h). Flight attendant seats that are provided for the airplane configuration should be installed near the approved floor level emergency exits. This should not be interpreted as a requirement to install flight attendant seats at each floor level exit. "Near" is defined in AC 25.785-1A. (Amendment 25-0)

(13) Paragraph (i). In order to reduce the deceleration "g" forces on occupants, some forward facing seats are designed to collapse. Usually, the design incorporates collapsible front legs. Such is acceptable if the collapse does not occur until a minimum of 8g has been applied.

After the collapse has occurred, the ultimate load of 9g should be applied and maintained for the required three seconds. The activation of the energy absorbing feature should not result in occupant injury. Various dimensions, such as 35-inches to injurious object clearance, aisle width and clearance, and interference with exits, should be evaluated before and after activation of the energy absorbing feature. Required dimensional clearances, such as aisles, passageways, flight attendant assist spaces, exit opening envelopes, and clearance between seats and potentially injurious surfaces must be maintained after the energy-absorbing feature is activated. The final position of the seat should not trap occupants. When testing a seat to demonstrate compliance with the static requirements of § 25.561, the testing should be conducted with an occupant center of gravity (CG) location as defined in NAS 809 (referenced in Technical Standard Order (TSO) C39) and AS8049 (referenced in the current version of TSO-C127). This CG location should be utilized in any airplane interface load analysis conducted. (Amendment 25-0)

(14) Paragraph (i). Technical Standard Order (TSO)-C22 is applicable only to seat belts. Technical Standard Order C114 may be applicable to shoulder harnesses, or they may be

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92 approved as part of the airplane. Sled tests with anthropomorphic dummies have shown that shoulder harness loads for forward facing seats can vary between 40 percent and 60 percent of the total load. Therefore, it is acceptable to substantiate a shoulder harness load of 60 percent (Refer to AC 25.785-1A, “Flight Attendant Seat and Torso Restraint System Installations,” dated 1/6/94): 0.6x9gx170 lbs = 918 lbs. If the seat belt is not approved under TSO-C22 or later revision, it should be approved as part of the airplane. The seat belt should be substantiated for 100 percent of the occupant load: 9g x 170 lbs = 1530 lbs. This is necessary even if the shoulder harness is permanently attached to the seat belt, since it is usually possible to utilize the seat belt without using the shoulder harness. The l.33 fitting factor is applicable to these configurations.

(Amendment 25-0)

(15) Paragraph (i)(1)(i). A seat is normally approved to TSO-C39 or later revision.

This approval may not account for the critical load when occupied by less than maximum occupants, e.g., one or two occupants in a triple seat. In some seat designs, occupancy by less than the maximum could be a critical design load for a particular structural member. All possible combinations of seat place occupancy should be substantiated by test or analysis. The loads for underseat baggage restraint systems attached to the seat should be added to seat loads.

Refer to § 25.787 guidance for underseat baggage criteria. This can be done by the TSO manufacturer when doing the TSO substantiation or by the applicant who is installing the seat.

(Amendment 25-0)

(16) Paragraph (i)(3). The l.33 factor is only required to be applied to the stated attachments. This factor should be applied to both ends of each attachment, (i.e., the seat end and the airplane end) and the fitting. If the applicant wishes to test the entire seat and belt assembly to this l.33 factor, it is satisfactory. (Amendment 25-0)

85. AMENDMENT 25-51, Effective March 6, 1980.

a. Regulation.

(a) Each seat, berth, safety belt, harness, and adjacent part of the airplane at each station designated as occupiable during takeoff and landing must be designed so that a person making proper use of these facilities will not suffer serious injury in an emergency landing as a result of the inertia forces specified in § 25.561.

(b) Each seat and berth must be approved.

(c) Each occupant of a seat that makes more than an 18 degree angle with the vertical plane containing the airplane centerline, must be protected from head injury by a safety belt and an energy absorbing rest that will support the arms, shoulders, head, and sine, or by a safety belt and shoulder harness that will prevent the head from contacting any injurious object. Each occupant of any other seat must be protected from head injury by a safety belt and, as appropriate to the type, location, and angle of facing of each seat, by one or more of the following:

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(1) A shoulder harness that will prevent the head from contacting any injurious object.

(2) The elimination of any injurious object within striking radius of the head.

(3) An energy absorbing rest that will support the arms, shoulders, head, and spine.

(d) If the seat backs do not have a firm hand hold, there must be a hand grip or rail along each aisle to enable occupants to steady themselves while using the aisles in moderately rough air.

(e) Each projecting object that would injure persons seated or moving about the airplane in normal flight must be padded.

(f) Each berth must be designed so that the forward part has a padded end board, canvas diaphragm, or equivalent means, that can withstand the static load reaction of the occupant when subjected to the forward inertia force specified in § 25.561.

Berths must be free from corners and protuberances likely to cause serious injury to a person occupying the berth during emergency conditions.

[(g) Each seat at a flight deck station must have a combined safety belt and shoulder harness with a single-point release that permits the flight desk occupant, when seated with safety belt and shoulder harness fastened, to perform all of the occupant's necessary flight deck functions. There must be a means to secure each combined safety belt and shoulder harness when not in use, to prevent interference with the operation of the airplane and with rapid egress in an emergency.

(h) Flight attendant seats in passenger compartments must be near required floor level emergency exits and be equipped with a restraint system consisting of a combined safety belt and shoulder harness unit with a single point release. There must be means to secure each combined safety belt and shoulder harness, when not in use, to prevent interference with rapid egress in an emergency. In addition-

(1) To the extend possible without compromising their proximity to required floor level emergency exits, flight attendant seats must be located to provide a direct view of the cabin area for which the flight attendant is individually responsible.

(2) Flight attendant seats must-

(i) Either be forward or rearward facing, with an energy absorbing rest that is designed to support the arms, shoulders, head, and spine; and

(ii) Be positioned so that when not in use they will not interfere with the use of passageways and exits.

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(i) Each seat, berth, and its supporting structure, must be designed for an occupant weight of 170 pounds, considering the maximum load factors, inertia forces, and reactions between the occupant, seat, and safety belt, harness or both at each relevant flight and ground load condition (including the emergency landing conditions prescribed in § 25.561). For berths, the forward inertia force must be considered in accordance with paragraph (f) of this section and need not be considered with respect to the safety belt. In addition-]

(1) The structural analysis and testing of the seats, berths, and their supporting structures may be determined by-

(i) Assuming that the critical load in the forward, sideward, downward, and rearward directions (as determined from the prescribed flight, ground, and emergency landing conditions) acts separately; and

(ii) Using selected combinations of loads if the required strength in each specified direction is substantiated;

(2) Each pilot seat must be designed for the reactions resulting from the application of the pilot forces prescribed in § 25.395; and

(3) The inertia forces specified in § 25.561 must be multiplied by a factor of 1.33 (instead of the fitting factor prescribed in § 25.625) in determining the strength of the attachment of-

(i) Each seat to the structure; and

(ii) Each belt or harness to the seat or structure.

(j) Each flight attendant seat must be located to minimize the probability of its occupant suffering injury by being struck by items dislodged in a galley, or from a stowage compartment or serving cart. All items expected in these locations in service must be considered.

(k) Each forward observer's seat required by the operating rules must be shown to be suitable for use in conducting the enroute inspections prescribed by § 121.581(a).]

b. Guidance.

(l) Paragraph (a). In order for the seat belt to be effective, it should be positioned to lay across the hip bone and ideally be about 45 degrees from the horizontal. An acceptable range for this angle is 35 degrees to 55 degrees. An acceptable range for the shoulder harness is 30 degrees above to 5 degrees below the horizontal. Refer to ACs 25.785-1A, “Flight Attendant Seat and Torso Restraint System Installations,” dated 1/6/94, and 43.13-1A, “Acceptable Methods, Techniques, and Practices-Aircraft Inspection and Repair (with Errata Sheet),” dated

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95 4/17/72, for related guidance. When testing a seat to demonstrate compliance with the static requirements of § 25.561, the testing should be conducted with an occupant center of gravity (CG) location as defined in NAS 809 (referenced in Technical Standard Order (TSO) C39) and AS8049 (referenced in the current version of TSO-C127). This CG location should be utilized in any airplane interface load analysis conducted. (Amendment 25-0)

(2) Paragraphs (a) and (c). The FAA issued policy memorandum ANM-03-115-28, dated October 2, 2003, and titled “Policy Statement on Use of Surrogate Parts When Evaluating Seatbacks and Seatback Mounted Accessories for Compliance with §§ 25.562(c) (5) and

25.785(b) and (d). This policy may be used with any test method used to demonstrate compliance with blunt force trauma for items mounted on the seatback. The policy is applicable to Amendment 25-51, for §§ 25.785 (a) and (c) as follows: (Amendment 25-0)

(i) In many row-to-row seat configurations, seatback mounted accessories are installed within the head paths of forward facing seated occupants. In order to demonstrate compliance with the aforementioned requirements, tests are conducted to assess the injury potential of these seatbacks and accessories. This policy only addresses head injury caused by blunt trauma. It does not address parts that become loose or sharp projections that are formed that may be injurious to a seated occupant during a head impact.

(ii) The types of tests that are conducted for blunt trauma assessments are dependant on the certification basis of the airplane. Typically, airplanes which do not have § 25.562(c)(5) in their certification basis, must still comply with the more general occupant protection requirements of §§ 25.785(a) and (c). Sections 25.785(a) and (c) require that a seat be designed so that an occupant would not suffer “serious injury” in an emergency landing and that injurious objects within the striking radius of the head be eliminated. As a result, seatbacks/accessories on these airplanes must be evaluated to ensure that an occupant would not suffer serious head injury from blunt trauma.

(iii) Currently, blunt trauma tests are conducted with seatback mounted accessories represented by actual production parts or parts that are similar in construction to the production parts. Industry has informed the FAA that certification delays occur due to the unavailability of actual accessories for testing. In addition, accessories are typically damaged during certification tests and are not usable in subsequent tests or for installation and delivery to a customer. Several specimens of the same part are repeatedly used, and damaged, during certification tests due to test failures or substantiating alternate seatback designs. This results in significant costs to manufacturers and customers.

(iv) The FAA has determined that it is acceptable to use a surrogate test article made of 6061-T4 aluminum which meets the criteria below in lieu of an accessory for demonstrating compliance with §§ 25.785(a) and (c) for blunt trauma assessments. An exception to the use of the surrogate test article occurs when the accessory is more rigid (deflects less and absorbs less energy during impact) than the plate defined in this AC. In that case, the accessory should be used in the test(s) and not a surrogate test article. The following criteria are applicable when using a surrogate test article during blunt trauma testing in accordance with §§ 25. 785(a) and (c):

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96 (A) The surrogate part should be fabricated from 6061-T4 aluminum and have a minimum thickness of 0.238-inch (i.e., 0.25-inch minus a 0.012-inch manufacturing tolerance) at all locations. The length and width of the surrogate part should equal, within tolerances, the length and width of the actual part, respectively.

(B) The exposed surface of the surrogate part that will be impacted should be flat. That is, it is not required to have the contour of the accessory’s exposed surface represented by the surrogate part. Note that this is based on typical accessory installations which are essentially mounted flush with the seatback and have a generally homogeneous contact area.

Small variations in the surface due to the contour of plastic parts may be ignored. Designs that differ from this (e.g., a design with an exposed structural protrusion) might require the exposed surface of the actual part to be represented in order to adequately assess head injury potential.

(C) The weight of the surrogate part, and additional ballast if needed, should be ±10 percent of the weight of the actual part.

(D) The surrogate part should be located on the seatback in the same place

(i.e., within manufacturing tolerances for mounting the actual part) where the actual part would be located in terms of the x and y coordinates in Figure 85-1. The surrogate part should be located such that the surface, which will be contacted during the test, is at the same location (i.e., within manufacturing tolerances for mounting the actual part) where the actual part would be in terms of the z coordinate (refer to figure 85-1).

(E) The surrogate part should be attached to the seat by the final production hardware or a conservative representation of the final production hardware. For substantiating blunt trauma requirements, a conservative representation of the attachment hardware would be at least as rigid as the actual hardware. The surrogate part should be mounted so that it would not move farther or faster, with respect to the seatback, than the actual part during the test.

(F) If the surrogate part cracks during a test, the test results are invalid.

(G) A surrogate part made of a material and thickness other than 6061-T4 aluminum in a nominal thickness of 0.25-inch may be used if an FAA Aircraft Certification Office finds that it is at least as rigid (i.e., it deflects less and absorbs less energy during the test).

Surrogate test articles which are less rigid than the aluminum surrogate part defined above are not addressed in this AC. If an applicant desires to use a surrogate part which is less rigid, its use should be approved through the issue paper process (or equivalent) or by an FAA policy memorandum. Testing may be required to determine the acceptability of these less rigid surrogate parts.

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FIGURE 85-1 SURROGATE PART INSTALLED ON SEATBACK Surrogate part installed on the back side of the seatback in lieu of the actual accessory.

The x and y axes are in the plane of the backside of the seatback 97

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(3) Paragraphs (a) and (c). The FAA issued policy memorandum ANM-03-115-31, dated May 9, 2005, and titled “Policy Statement on Conducting Component Level Tests to Demonstrate Compliance with §§ 25.785(b) and (d).” Appendix 13 of this AC contains the complete policy memorandum. Applicants may use the test methods described in Appendix 13 to demonstrate compliance with §§ 25.785(a) and (c) for both blunt force trauma and formation of post-impact sharp or injurious edges or features for items within the head strike zone as defined in figure 85-2. The policy is applicable to design certification projects whose certification basis includes Amendment 25-51, for §§ 25.785 (a) and (c). (Amendment 25-0)

(4) Paragraph (c). For sideward facing seats, this change removed the option of a safety belt, and eliminated the possibility of locating any injurious object within striking radius of the head. This option is still satisfactory for forward and aft facing seats. The "human cushion" or unpadded bulkhead concept is not an adequate energy absorbing rest and therefore does not comply with this amendment of the regulation. The shoulder harness may be a diagonal shoulder harness over the forward shoulder. (Amendment 25-15)

(5) Paragraph (c). The 18-degree requirement applies to both forward and aft facing seat installations. If the forward direction is considered as 0 degrees or 360 degrees of a circle, the segments from 18 degrees to 162 degrees and 198 degrees to 342 degrees are considered a side facing seat and the seat installation must comply with one of the two options stated in the regulation. (Amendment 25-20)

(6) Paragraph (c)(2). The striking radius of the head for a forward facing seat (head strike zone) is considered to be a zone whose length is bounded between an arc at the shoulder height of the 5th percentile female occupant (20.5-inches) and an arc at the limit of the head path (35-inches) whose centers are at the intersection of the plane of the uncompressed top of the seat bottom cushion with the plane of the uncompressed front of the back cushion; commonly referred to as the cushion reference point (CRP), as shown in figure 85-2. Previously this was referred to as seat reference point (SRP). However, with the advent of dynamic seat testing the definition for SRP was changed (refer to SAE ARP5526D). The head strike zone extends in the direction parallel to the airplane longitudinal axis. The width of the head strike zone is bounded by a vertical plane through the intersection of the centerlines of each armrest and the CRP as shown in figure 85-2. Typical installations to be considered are bulkheads, cabinets, tables, and passenger evacuation slide covers. The installation should not contain any pointed corners or sharp edges. The testing used to demonstrate that the installation is not injurious must take into account whether the system (e.g., seatback mounted telephone) is allowed to be used during taxi, takeoff and landing. If the system is allowed to be used during these phases of operation, the testing must consider the system in both the deployed and stowed position (e.g., seatback mounted telephone in or out of the cradle). If a surface or interior feature is located such that it is potentially hazardous in a combination of forward and side loads, it should be substantiated even if it might be slightly outside of the head strike zone. Any surface less than 18-inches above the floor need not be considered. Surfaces within the head strike zone may be padded with energy absorbing material, such as one inch of either Ensolite (Type AH, AHC, IV3, HHC or HH), Klegecell, or Airex 4070. Foam rubber is not satisfactory since it is an energy storing material. If the padding is easily removed, there should be acceptable placarding requiring the padding be in place during taxi, takeoff, and landing. (Amendment 25-0)

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FIGURE 85-2 HEAD STRIKE ZONE FOR § 25.785 Head Strike Zone

20.5 inch 35 inch arc arc CRP 18 inches CRP Centerline 35 inch arc of Armrest Seat Axis Airplane Longitudinal Axis Centerline of Armrest Seat Axis ‚CRP Airplane Centerline Longitudinal Axis of Armrest 35 inch arc Centerline of Armrest 99

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(7) Paragraph (c)(2). A flat surface within the 35-inch head strike arc, such as a table or partition, may be tested to the criteria of Society of Automotive Engineers (SAE) J921 or the following criteria. Impact injury criteria is discussed in AC 21-22, Injury Criteria for Human Exposure to Impact. (Amendment 25-0)

(i) A 13-pound bowling ball may be used to simulate the head of a 170-pound person whose seat belt is fastened and is subjected to 9g. (Amendment 25-0)

(ii) The ball shall impact the surface with at least 2780-inch-pounds of energy.

(Amendment 25-0)

(iii) The attachments of the test article shall not fail completely. (Amendment 25-0)

(iv) No parts shall become loose or sharp projections be formed that would be hazardous to the passengers. (Amendment 25-0)

(v) The test article may deform locally. (Amendment 25-0)

(vi) The surface being tested should perform equal to or better than a previously approved surface. The intent of this comparative test method is to test similar items (e.g., a seatback that does not have a telephone with a seatback that has a telephone installed). This test method should not be used to compare a seatback to an armrest. (Amendment 25-0)

(8) Paragraph (c)(2). (Amendment 25-0)

(i) Some passenger seats are designed with armrests that pivot upward such that the armrest could protrude beyond the seatbacks resulting in a potentially hazardous condition to persons seated behind these seats. Armrests that are adequately delethalized or restricted such that they cannot protrude aft of either seatback in any position are acceptable. (Amendment 25-0)

(ii) Armrests that are offset can be within the headstrike path of an occupant to the rear. Armrests within the striking radius of the head that are:

(A) bounded on both sides of the armrest by the seat backs and are offset more than 2-inches from the armrests of the seat to the rear, or (B) forward of an additional (exposed) seat in the row behind it, such that the forward armrest is bounded on one side only are considered to be injurious objects. The head must be protected from these injurious objects by some additional means such as padding.

Armrests that are bounded only on one side and not offset from the armrest of the seat in the rear are not considered to be injurious objects. (Amendment 25-0)

(9) Paragraph (c)(2). The FAA issued policy memorandum 02-115-15, dated November 25, 2002, titled “New Policy with respect to compliance with § 25.785(d), Amendment 25-88, for certification of passenger seat armrests.” The policy in this

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101 memorandum may be used for demonstrating compliance with § 25.785(c)(2), Amendment 25- 51, and is provided below.

(i) Armrests that might possibly be struck by persons seated behind (aft of) them are characterized as “bounded” or “unbounded.” Bounded armrests are defined as follows:

(A) An armrest that has a seatback on both sides, with the distance between the structure of the adjacent seatbacks no greater than five inches, or (B) An armrest that has a seatback on one side and the airplane sidewall panel or a wall that is part of an airplane furnishing (e.g., galley, closet, lavatory) on the other side with the distance between the structure of the seatback and the panel/wall no greater than five inches.

(ii) For purposes of this AC, the structure of the seatback is considered to be the parts of the seatback with load carrying capability. It does not include upholstery material or soft foam installed for occupant comfort. In some seat designs there is a metal frame in the seatback that forms the support structure to which the foam and upholstery are used to provide the shape of the seatback. When measuring the distance between the structure of the adjacent seatbacks of no greater than five inches, the measurement would be between these metal or composite supports structures.

(iii) Unbounded armrests are those that do not meet either definition above.

Additionally, seat places that are located aft of unbounded armrests may be characterized as either “exposed” or “non-exposed.” The non-exposed seat place is typically an aisle seat place,

i.e., located adjacent to a passenger aisle (refer to figure 85-3). The exposed seat place is typically located where the number of seats in the row forward is different from that of the seat row aft. For example, near Type III overwing exits, many airplanes have a double seat installed inboard of the exit with an empty space between the seat and the exit. The seat row aft of the double seat has a triple seat (Refer to figure 85-4). In Figure 85-4, seat place “A” is an exposed seat place that makes the outboard armrest of the double seat an unbounded exposed armrest.

(iv) The definitions above apply to all armrests in the airplane as applicable. The existing policy contained in this AC paragraphs 81b(5) and 81b(7) are still applicable to the armrests identified in the new policy below.

(A) Note: The policy below addresses armrests within the 35-inch head strike arc and surfaces 18-inches and greater above the floor. Armrests outside the 35-inch head strike arc and armrest surfaces less than 18-inches above the floor are acceptable as defined in this AC paragraphs 81b(5) and 81b(7).

(B) An armrest is acceptable by inspection if the armrests of two consecutive

(i.e., one aft of the other) seat assemblies (seats need not be of the same part number) are offset no greater 0.5-inch total, including design and production tolerances.

(C) Bounded armrests and non-exposed unbounded armrests are acceptable if:

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(1) The armrests of two consecutive seat assemblies are offset greater than 0.5-inch but no greater than two (2)-inches total, including design, and production tolerances, and

(2) The breakover feature of the seatback(s) adjacent to the armrest in the forward seat assembly is (are) locked out.

(D) The seatback breakover feature may be locked out by any method that requires a tool to release the lock out provision. The lockout of the breakover feature must be effective for the seatback in the upright position used for taxi, takeoff, and landing. Seatbacks incorporating an energy absorbing feature to meet the HIC requirements of § 25.562 are considered to have the breakover lockout and are acceptable. Whatever the method of seatback breakover lock out, there typically is some movement of the seatback. This movement of the seatback is acceptable as long as when the seatback is moved to the worst case position by a small hand load applied to the top of the seatback, the armrest is still afforded protection by the seatback, with the end of the top of the armrest being forward of the aft side of the seatback.

(E) Bounded armrests and non-exposed unbounded armrests, where the offset is greater than two (2)-inches total, including design and production tolerances, need to be addressed as being injurious objects within the striking radius of the head, e.g., by padding the armrest.

(F) Exposed unbounded armrests; if the armrests of two consecutive seat assemblies that are offset by more than 0.5-inch total, including design and production tolerances, need to be addressed as being injurious objects within the striking radius of the head,

e.g., by padding the armrest.

(G) Armrests that are padded (using appropriate padding material as described in paragraph 81b(5) of this AC) must have the padding cover the length of the armrest that is encompassed by 35-inch and smaller head strike arcs. Bounded armrests, where the seatback(s) have the breakover feature locked out, need not be padded to encompass the entire 35-inch head strike arc because the seatbacks prevent the contact of the armrest on the forward side of the seatback(s). Therefore, these armrests need only be padded to the forward edge of the seatback(s) in their upright position achieved after the small hand force is applied to the seatback. Portions of the armrest surface that cannot be contacted by the head are not required to be padded, e.g., the lower (or under) surface of a curved armrest.

(H) As an alternative to the use of padding, surfaces within the striking radius of the head that translate out of the striking radius under a nominal (10 pound) load may be considered to provide adequate protection, e.g., armrests that have been pivoted upward, which pivot downward out of the head strike arc under the nominal load. During an evaluation of this feature, the load must be applied in a direction that approximates the motion of a seated and belted occupant in the seat aft of the armrest under crash conditions.

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**103 FIGURE 85-3 ARMREST OFFSET**

**FIGURE 85-4 NON-EXPOSED AND EXPOSED ARMREST**

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(10) Paragraph (d). The seat back may serve as a firm hand hold. Since many seats are capable of breaking over, the breakover load must be adequate to be considered firm. A load of 25 lbs minimum, acting horizontally, is considered adequate when applied at the top center of the seat back. (Refer to paragraph 411b.(10) for maximum breakover force.) Very large seat pitches (in excess of 65-inches) may not permit the seatbacks to act as a handhold. This is due to both distance between the seatbacks and the capability of the seats to have very large amounts of recline. In this case, it may be necessary to install supplementary features to serve as handholds.

Seat mounted headrests that move relative to the seatback do not need to be assessed for their ability to provide a firm handhold, provided the seatback remains available for use as a handhold, and meets the criteria identified above. Other interior features such as class dividers, closets and other monuments may also serve as acceptable handholds if they provide a surface for occupants to push against to steady themselves while moving about the cabin interior.

(Amendment 25-0)

(11) Paragraph (f). Each berth installation should include a seat belt located approximately at the occupant's pelvis. For a berth installation with the feet facing forward, a bag, enclosing the legs to catch the upper torso when subjected to 9g, would be satisfactory in lieu of a padded end board. If the head is facing forward, a strap over each shoulder configuration would be satisfactory. If the berth is side facing, a padded side board or two belts, located approximately at the thighs and approximately at the chest, would be satisfactory.

(Amendment 25-0)

(12) Paragraphs (g) and (h). The combined safety belt and shoulder harness should consist of a standard safety belt and a shoulder harness with a strap over each shoulder. The shoulder harness straps should be as close to the neck as possible and may join behind the neck or each strap may attach separately to structure. In the front, the shoulder harness straps should attach to the buckle or safety belt near the buckle. Some harness geometries have been found acceptable where the shoulder harness straps are attached to the seat belt attach fittings. Ideally, the buckle should be located near the center of the torso. The single point release should be one action in which both the safety belt and shoulder harness are released simultaneously. The means provided to secure each combined safety belt and harness should be designed so that the belt and harness strap material does not get repeatedly creased over a long period of wear.

(Amendment 25-51)

(13) Paragraphs (g), (h) and (j). Refer to AC 25.785-lA, Flight Attendant Seat and Torso Restraint System Installations, dated 1/6/94, for additional acceptable means of compliance. (Amendment 25-51)

(14) Paragraph (h). Flight attendant seats that are provided for t he airplane configuration should be installed near the approved floor level emergency exits. This should not be interpreted as a requirement to install flight attendant seats at each floor level exit. "Near" is defined in AC 25.785-1A. (Amendment 25-0)

(15) Paragraph (i). In order to reduce the deceleration "g" forces on occupants, some forward facing seats are designed to collapse. Usually, the design incorporates collapsible front

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105 legs. Such is acceptable if the collapse does not occur until a minimum of 8g has been applied.

After the collapse has occurred, the ultimate load of 9g should be applied and maintained for the required three seconds. The activation of the energy absorbing feature should not result in occupant injury. Various dimensions, such as 35-inches to injurious object clearance, aisle width and clearance, and interference with exits, should be evaluated before and after activation of the energy absorbing feature. Required dimensional clearances, such as aisles, passageways, flight attendant assist spaces, exit opening envelopes, and clearance between seats and potentially injurious surfaces must be maintained after the energy-absorbing feature is activated. The final position of the seat should not trap occupants. When testing a seat to demonstrate compliance with the static requirements of § 25.561, the testing should be conducted with an occupant center of gravity (CG) location as defined in NAS 809 (referenced in Technical Standard Order (TSO) C39) and AS8049 (referenced in the current version of TSO-C127). This CG location should be utilized in any airplane interface load analysis conducted. (Amendment 25-0)

(16) Paragraph (i). Technical Standard Order (TSO)-C22 is applicable only to seat belts. Technical Standard Order C114 may be applicable to shoulder harnesses, or they may be approved as part of the airplane. Sled tests with anthropomorphic dummies have shown that shoulder harness loads for forward facing seats can vary between 40 percent and 60 percent of the total load. Therefore, it is acceptable to substantiate a shoulder harness load of 60 percent (Refer to AC 25.785-1A, “Flight Attendant Seat and Torso Restraint System Installations,” dated 1/6/94): 0.6x9gx170 lbs = 918 lbs. If the seat belt is not approved under TSO-C22 or later revision, it should be approved as part of the airplane. The seat belt should be substantiated for 100 percent of the occupant load: 9g x 170 lbs = 1530 lbs. This is necessary even if the shoulder harness is permanently attached to the seat belt, since it is usually possible to utilize the seat belt without using the shoulder harness. The l.33 fitting factor is applicable to these configurations.

(Amendment 25-0)

(17) Paragraph (i)(1)(i). A seat is normally approved to TSO-C39 or later revision.

This approval may not account for the critical load when occupied by less than maximum occupants, e.g., one or two occupants in a triple seat. In some seat designs, occupancy by less than the maximum could be a critical design load for a particular structural member. All possible combinations of seat place occupancy should be substantiated by test or analysis. The loads for underseat baggage restraint systems attached to the seat should be added to seat loads.

Refer to § 25.787 guidance for underseat baggage criteria. This can be done by the TSO manufacturer when doing the TSO substantiation or by the applicant who is installing the seat.

(Amendment 25-0)

(18) Paragraph (i)(3). The l.33 factor is only required to be applied to the stated attachments. This factor should be applied to both ends of each attachment, (i.e., the seat end and the airplane end) and the fitting. If the applicant wishes to test the entire seat and belt assembly to this l.33 factor, it is satisfactory. (Amendment 25-0)

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86. AMENDMENT 25-64, Effective June 16, 1988.

a. Regulation.

[(a) Each seat, berth, safety belt, harness, and adjacent part of the airplane at each station designated as occupiable during takeoff and landing must be designed so that a person making proper use of these facilities will not suffer serious injury in an emergency landing as a result of inertia forces specified in § 25.561 and 25.562.]

(b) Each seat and berth must be approved.

(c) Each occupant of a seat that makes more than an 18 degree angle with the vertical plane containing the airplane centerline, must be protected from head injury by a safety belt and an energy absorbing rest that will support the arms, shoulders, head, and sine, or by a safety belt and shoulder harness that will prevent the head from contacting any injurious object. Each occupant of any other seat must be protected from head injury by a safety belt and, as appropriate to the type, location, and angle of facing of each seat, by one or more of the following:

(1) A shoulder harness that will prevent the head from contacting any injurious object.

(2) The elimination of any injurious object within striking radius of the head.

(3) An energy absorbing rest that will support the arms, shoulders, head, and spine.

(d) If the seat backs do not have a firm hand hold, there must be a hand grip or rail along each aisle to enable occupants to steady themselves while using the aisles in moderately rough air.

(e) Each projecting object that would injure persons seated or moving about the airplane in normal flight must be padded.

(f) Each berth must be designed so that the forward part has a padded end board, canvas diaphragm, or equivalent means, that can withstand the static load reaction of the occupant when subjected to the forward inertia force specified in § 25.561.

Berths must be free from corners and protuberances likely to cause serious injury to a person occupying the berth during emergency conditions.

(g) Each seat at a flight deck station must have a combined safety belt and shoulder harness with a single-point release that permits the flight desk occupant, when seated with safety belt and shoulder harness fastened, to perform all of the occupant's necessary flight deck functions. There must be a means to secure each combined safety belt and shoulder harness when not in use, to prevent interference with the operation of the airplane and with rapid egress in an emergency.

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(h) Flight attendant seats in passenger compartments must be near required floor level emergency exits and be equipped with a restraint system consisting of a combined safety belt and shoulder harness unit with a single point release. There must be means to secure each combined safety belt and shoulder harness, when not in use, to prevent interference with rapid egress in an emergency. In addition-

(1) To the extend possible without compromising their proximity to required floor level emergency exits, flight attendant seats must be located to provide a direct view of the cabin area for which the flight attendant is individually responsible.

(2) Flight attendant seats must-

(i) Either be forward or rearward facing, with an energy absorbing rest that is designed to support the arms, shoulders, head, and spine; and

(ii) Be positioned so that when not in use they will not interfere with the use of passageways and exits.

(i) Each seat, berth, and its supporting structure, must be designed for an occupant weight of 170 pounds, considering the maximum load factors, inertia forces, and reactions between the occupant, seat, and safety belt, harness or both at each relevant flight and ground load condition (including the emergency landing conditions prescribed in § 25.561). For berths, the forward inertia force must be considered in accordance with paragraph (f) of this section and need not be considered with respect to the safety belt. In addition-

(1) The structural analysis and testing of the seats, berths, and their supporting structures may be determined by-

(i) Assuming that the critical load in the forward, sideward, downward, and rearward directions (as determined from the prescribed flight, ground, and emergency landing conditions) acts separately; and

(ii) Using selected combinations of loads if the required strength in each specified direction is substantiated;

(2) Each pilot seat must be designed for the reactions resulting from the application of the pilot forces prescribed in § 25.395; and

(3) The inertia forces specified in § 25.561 must be multiplied by a factor of 1.33 (instead of the fitting factor prescribed in § 25.625) in determining the strength of the attachment of-

(i) Each seat to the structure; and

(ii) Each belt or harness to the seat or structure.

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(j) Each flight attendant seat must be located to minimize the probability of its occupant suffering injury by being struck by items dislodged in a galley, or from a stowage compartment or serving cart. All items expected in these locations in service must be considered.

(k) Each forward observer's seat required by the operating rules must be shown to be suitable for use in conducting the enroute inspections prescribed by § 121.581(a).

b. Guidance.

(1) Refer to AC 25.562-1B dated 1/10/2006, Dynamic Evaluation of Seat Restraint Systems & Occupant Protection on Transport Airplanes, dated 1/19/96, for detailed guidance concerning this amendment. (Amendment 25-64)

(2) Compliance with § 25.785(a) can be demonstrated using the tests required by § 25.562(b), and showing compliance with the associated injury criteria, for those objects that are assessed in those tests. However, because the tests specified in § 25.562 are limited to certain conditions, they may not address all areas that could be injurious, either in flight, or in an emergency landing. For this reason, simply showing that an object is outside the headstrike envelope produced in a dynamic test in accordance with § 25.562 is not sufficient to show compliance with 25.785(a). Objects may, in fact, require delethalization, even though they are not struck in a dynamic test. (Amendment 25-64)

(3) Paragraph (a). In order for the seat belt to be effective, it should be positioned to lay across the hip bone and ideally be about 45 degrees from the horizontal. An acceptable range for this angle is 35 degrees to 55 degrees. An acceptable range for the shoulder harness is 30 degrees above to 5 degrees below the horizontal. Refer to ACs 25.785-1A, “Flight Attendant Seat and Torso Restraint System Installations,” dated 1/6/94, and 43.13-1A, “Acceptable Methods, Techniques, and Practices-Aircraft Inspection and Repair (with Errata Sheet),” dated 4/17/72, for related guidance. When testing a seat to demonstrate compliance with the static requirements of § 25.561, the testing should be conducted with an occupant center of gravity (CG) location as defined in NAS 809 (referenced in Technical Standard Order (TSO) C39) and AS8049 (referenced in the current version of TSO-C127). This CG location should be utilized in any airplane interface load analysis conducted. (Amendment 25-0)

(4) Paragraphs (a) and (c). The FAA issued policy memorandum ANM-03-115-28, dated October 2, 2003, and titled “Policy Statement on Use of Surrogate Parts When Evaluating Seatbacks and Seatback Mounted Accessories for Compliance with §§ 25.562(c) (5) and

25.785(b) and (d). This policy may be used with any test method used to demonstrate compliance with blunt force trauma for items mounted on the seatback. The policy is applicable to Amendment 25-64, for §§ 25.785 (a) and (c) as follows: (Amendment 25-0)

(i) In many row-to-row seat configurations, seatback mounted accessories are installed within the head paths of forward facing seated occupants. In order to demonstrate compliance with the aforementioned requirements, tests are conducted to assess the injury

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109 potential of these seatbacks and accessories. This policy only addresses head injury caused by blunt trauma. It does not address parts that become loose or sharp projections that are formed that may be injurious to a seated occupant during a head impact.

(ii) The types of tests that are conducted for blunt trauma assessments are dependant on the certification basis of the airplane. Airplane certification bases, which include § 25.562(c)(5), require that protection be provided so that a head impact does not result in a HIC greater than 1,000 units under the dynamic test conditions specified in § 25.562(b). Typically, airplanes which do not have § 25.562(c)(5) in their certification basis, must still comply with the more general occupant protection requirements of §§ 25.785(b) and (d). Sections 25.785(b) and

(d) require that a seat be designed so that an occupant would not suffer “serious injury” in an emergency landing and that injurious objects within the striking radius of the head be eliminated.

As a result, seatbacks/accessories on these airplanes must be evaluated to ensure that an occupant would not suffer serious head injury from blunt trauma.

(iii) Currently, blunt trauma tests are conducted with seatback mounted accessories represented by actual production parts or parts that are similar in construction to the production parts. Industry has informed the FAA that certification delays occur due to the unavailability of actual accessories for testing. In addition, accessories are typically damaged during certification tests and are not usable in subsequent tests or for installation and delivery to a customer. Several specimens of the same part are repeatedly used, and damaged, during certification tests due to test failures or substantiating alternate seatback designs. This results in significant costs to manufacturers and customers.

(iv) The FAA has determined that it is acceptable to use a surrogate test article made of 6061-T4 aluminum which meets the criteria below in lieu of an accessory for demonstrating compliance with §§ 25.562(c)(5) and 25.785(b) and (d) for blunt trauma assessments. An exception to the use of the surrogate test article occurs when the accessory is more rigid (deflects less and absorbs less energy during impact) than the plate defined in this AC. In that case, the accessory should be used in the test(s) and not a surrogate test article. The following criteria are applicable when using a surrogate test article during blunt trauma testing in accordance with §§ 25.562(c)(5) and 25.785(b) and (d):

(A) The surrogate part should be fabricated from 6061-T4 aluminum and have a minimum thickness of 0.238-inch (i.e., 0.25-inch minus a 0.012-inch manufacturing tolerance) at all locations. The length and width of the surrogate part should equal, within tolerances, the length and width of the actual part, respectively.

(B) The exposed surface of the surrogate part that will be impacted should be flat. That is, it is not required to have the contour of the accessory’s exposed surface represented by the surrogate part. Note that this is based on typical accessory installations which are essentially mounted flush with the seatback and have a generally homogeneous contact area.

Small variations in the surface due to the contour of plastic parts may be ignored. Designs that differ from this (e.g., a design with an exposed structural protrusion) might require the exposed surface of the actual part to be represented in order to adequately assess head injury potential.

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110 (C) The weight of the surrogate part, and additional ballast if needed, should be ±10 percent of the weight of the actual part.

(D) The surrogate part should be located on the seatback in the same place

(i.e., within manufacturing tolerances for mounting the actual part) where the actual part would be located in terms of the x and y coordinates in Figure 86-1. The surrogate part should be located such that the surface, which will be contacted during the test, is at the same location (i.e., within manufacturing tolerances for mounting the actual part) where the actual part would be in terms of the z coordinate (Refer to figure 86-1).

(E) The surrogate part should be attached to the seat by the final production hardware or a conservative representation of the final production hardware. For substantiating blunt trauma requirements, a conservative representation of the attachment hardware would be at least as rigid as the actual hardware. The surrogate part should be mounted so that it would not move farther or faster, with respect to the seatback, than the actual part during the test. Note that a conservative representation of the attachment hardware for determining HIC may not adequately represent the attachment hardware for substantiating it to § 25.562 loads. However, if the attachment hardware is adequately represented for substantiating it to § 25.562 loads, the test using a surrogate part may also be used to demonstrate that the attachment hardware will retain the actual accessory under § 25.562 loads.

(F) If the surrogate part cracks during a test, the test results are invalid.

(G) A surrogate part made of a material and thickness other than 6061-T4 aluminum in a nominal thickness of 0.25-inch may be used if an FAA Aircraft Certification Office finds that it is at least as rigid (i.e., it deflects less and absorbs less energy during the test).

Surrogate test articles which are less rigid than the aluminum surrogate part defined above are not addressed in this AC. If an applicant desires to use a surrogate part which is less rigid, its use should be approved through the issue paper process (or equivalent) or by an FAA policy memorandum. Testing may be required to determine the acceptability of these less rigid surrogate parts.

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FIGURE 86-1 SURROGATE PART INSTALLED ON SEATBACK Surrogate part installed on the back side of the seatback in lieu of the actual accessory.

The x and y axes are in the plane of the backside of the seatback 111

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(5) Paragraphs (a) and (c). The FAA issued policy memorandum ANM-03-115-31, dated May 9, 2005, and titled “Policy Statement on Conducting Component Level Tests to Demonstrate Compliance with §§ 25.785(b) and (d).” Appendix 13 of this AC contains the complete policy memorandum. Applicants may use the test methods described in Appendix 13 to demonstrate compliance with §§ 25.785(a) and (c) for both blunt force trauma and formation of post-impact sharp or injurious edges or features for items within the head strike zone as defined in figure 86-2. The policy is applicable to design certification projects whose certification basis includes Amendment 25-64, for §§ 25.785 (a) and (c). (Amendment 25-0)

(6) Paragraph (c). For sideward facing seats, this change removed the option of a safety belt, and eliminated the possibility of locating any injurious object within striking radius of the head. This option is still satisfactory for forward and aft facing seats. The "human cushion" or unpadded bulkhead concept is not an adequate energy absorbing rest and therefore does not comply with this amendment of the regulation. The shoulder harness may be a diagonal shoulder harness over the forward shoulder. (Amendment 25-15)

(7) Paragraph (c). The 18-degree requirement applies to both forward and aft facing seat installations. If the forward direction is considered as 0 degrees or 360 degrees of a circle, the segments from 18 degrees to 162 degrees and 198 degrees to 342 degrees are considered a side facing seat and the seat installation must comply with one of the two options stated in the regulation. (Amendment 25-20)

(8) Paragraph (c)(2). The striking radius of the head for a forward facing seat (head strike zone) is considered to be a zone whose length is bounded between an arc at the shoulder height of the 5th percentile female occupant (20.5-inches) and an arc at the limit of the head path (35-inches), whose centers are at the intersection of the plane of the uncompressed top of the seat bottom cushion with the plane of the uncompressed front of the back cushion; commonly referred to as the cushion reference point (CRP), as shown in figure 86-2. Previously this was referred to as seat reference point (SRP). However, with the advent of dynamic seat testing the definition for SRP was changed (refer to SAE ARP5526D). The head strike zone extends in the direction parallel to the airplane longitudinal axis. The width of the head strike zone is bounded by a vertical plane through the intersection of the centerlines of each armrest and the CRP as shown in figure 86-2. Typical installations to be considered are bulkheads, cabinets, tables, and passenger evacuation slide covers. The installation should not contain any pointed corners or sharp edges. The testing used to demonstrate that the installation is not injurious must take into account whether the system (e.g., seatback mounted telephone) is allowed to be used during taxi, takeoff and landing. If the system is allowed to be used during these phases of operation, the testing must consider the system in both the deployed and stowed position (e.g., seatback mounted telephone in or out of the cradle). If a surface or interior feature is located such that it is potentially hazardous in a combination of forward and side loads, it should be substantiated even if it might be slightly outside of the head strike zone. Any surface less than 18-inches above the floor need not be considered. Surfaces within the head strike zone may be padded with energy absorbing material, such as one inch of either Ensolite (Type AH, AHC, IV3, HHC or HH), Klegecell, or Airex 4070. Foam rubber is not satisfactory since it is an energy storing material. If the padding is easily removed, there should be acceptable placarding requiring the padding be in place during taxi, takeoff, and landing. Compliance with § 25.562(c)(5) can be used to show compliance to § 25.785(c)(2) for those areas struck by the ATD head during dynamic testing.

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See AC 25.562-1B, "Dynamic Evaluation of Seat Restraint Systems and Occupant Protection on Transport Airplanes." (Amendment 25-64) FIGURE 86-2 HEAD STRIKE ZONE FOR § 25.785 Head Strike Zone

20.5 inch 35 inch arc arc CRP 18 inches ¡CRP Centerline 35 inch arc of Armrest Seat Axis Airplane Longitudinal Axis Centerline of Armrest Seat Axis ‚CRP Airplane Centerline Longitudinal Axis of Armrest 35 inch arc Centerline of Armrest 113

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(9) Paragraph (c)(2). A flat surface within the 35-inch head strike arc, such as a table or partition, may be tested to the criteria of Society of Automotive Engineers (SAE) J921 or the following criteria. Impact injury criteria is discussed in AC 21-22, Injury Criteria for Human Exposure to Impact. (Amendment 25-0)

(i) A 13-pound bowling ball may be used to simulate the head of a 170-pound person whose seat belt is fastened and is subjected to 9g. (Amendment 25-0)

(ii) The ball shall impact the surface with at least 2780-inch-pounds of energy.

(Amendment 25-0)

(iii) The attachments of the test article shall not fail completely. (Amendment 25-0)

(iv) No parts shall become loose or sharp projections be formed that would be hazardous to the passengers. (Amendment 25-0)

(v) The test article may deform locally. (Amendment 25-0)

(vi) The surface being tested should perform equal to or better than a previously approved surface. The intent of this comparative test method is to test similar items (e.g., a seatback that does not have a telephone with a seatback that has a telephone installed). This test method should not be used to compare a seatback to an armrest. (Amendment 25-0)

(10) Paragraph (c)(2). (Amendment 25-0)

(i) Some passenger seats are designed with armrests that pivot upward such that the armrest could protrude beyond the seatbacks resulting in a potentially hazardous condition to persons seated behind these seats. Armrests that are adequately delethalized or restricted such that they cannot protrude aft of either seatback in any position are acceptable. (Amendment 25-0)

(ii) Armrests that are offset can be within the headstrike path of an occupant to the rear. Armrests within the striking radius of the head that are:

(A) bounded on both sides of the armrest by the seat backs and are offset more than 2-inches from the armrests of the seat to the rear, or (B) forward of an additional (exposed) seat in the row behind it, such that the forward armrest is bounded on one side only are considered to be injurious objects. The head must be protected from these injurious objects by some additional means such as padding.

Armrests that are bounded only on one side and not offset from the armrest of the seat in the rear are not considered to be injurious objects. (Amendment 25-0)

(11) Paragraph (c)(2). The FAA issued policy memorandum 02-115-15, dated November 25, 2002, titled “New Policy with respect to compliance with § 25.785(d), Amendment 25-88, for certification of passenger seat armrests.” The policy in this

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115 memorandum may be used for demonstrating compliance with § 25.785(c)(2), Amendment 25- 64, and is provided below. (Amendment 25-0)

(i) Armrests that might possibly be struck by persons seated behind (aft of) them are characterized as “bounded” or “unbounded.” Bounded armrests are defined as follows:

(A) An armrest that has a seatback on both sides, with the distance between the structure of the adjacent seatbacks no greater than five inches, or (B) An armrest that has a seatback on one side and the airplane sidewall panel or a wall that is part of an airplane furnishing (e.g., galley, closet, lavatory) on the other side with the distance between the structure of the seatback and the panel/wall no greater than five inches.

(ii) For purposes of this AC, the structure of the seatback is considered to be the parts of the seatback with load carrying capability. It does not include upholstery material or soft foam installed for occupant comfort. In some seat designs there is a metal frame in the seatback that forms the support structure to which the foam and upholstery are used to provide the shape of the seatback. When measuring the distance between the structure of the adjacent seatbacks of no greater than five inches, the measurement would be between these metal or composite supports structures.

(iii) Unbounded armrests are those that do not meet either definition above.

Additionally, seat places that are located aft of unbounded armrests may be characterized as either “exposed” or “non-exposed.” The non-exposed seat place is typically an aisle seat place,

i.e., located adjacent to a passenger aisle (refer to figure 86-3). The exposed seat place is typically located where the number of seats in the row forward is different from that of the seat row aft. For example, near Type III overwing exits, many airplanes have a double seat installed inboard of the exit with an empty space between the seat and the exit. The seat row aft of the double seat has a triple seat (refer to figure 86-4). In figure 86-4, seat place “A” is an exposed seat place that makes the outboard armrest of the double seat an unbounded exposed armrest.

(iv) The definitions above apply to all armrests in the airplane as applicable. The existing policy contained in this AC paragraphs 81b(5) and 81b(7) are still applicable to the armrests identified in the new policy below.

(A) Note: The policy below addresses armrests within the 35-inch head strike arc and surfaces 18-inches and greater above the floor. Armrests outside the 35-inch head strike arc and armrest surfaces less than 18-inches above the floor are acceptable as defined in this AC paragraphs 81b(5) and 81b(7).

(B) An armrest is acceptable by inspection if the armrests of two consecutive

(i.e., one aft of the other) seat assemblies (seats need not be of the same part number) are offset no greater 0.5-inch total, including design and production tolerances.

(C) Bounded armrests and non-exposed unbounded armrests are acceptable if:

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(1) The armrests of two consecutive seat assemblies are offset greater than 0.5-inch but no greater than two (2)-inches total, including design, and production tolerances, and

(2) The breakover feature of the seatback(s) adjacent to the armrest in the forward seat assembly is (are) locked out.

(D) The seatback breakover feature may be locked out by any method that requires a tool to release the lock out provision. The lockout of the breakover feature must be effective for the seatback in the upright position used for taxi, takeoff, and landing. Seatbacks incorporating an energy absorbing feature to meet the HIC requirements of § 25.562 are considered to have the breakover lockout and are acceptable. Whatever the method of seatback breakover lock out, there typically is some movement of the seatback. This movement of the seatback is acceptable as long as when the seatback is moved to the worst case position by a small hand load applied to the top of the seatback, the armrest is still afforded protection by the seatback, with the end of the top of the armrest being forward of the aft side of the seatback.

(E) Bounded armrests and non-exposed unbounded armrests, where the offset is greater than two (2)-inches total, including design and production tolerances, need to be addressed as being injurious objects within the striking radius of the head, e.g., by padding the armrest.

(F) Exposed unbounded armrests; if the armrests of two consecutive seat assemblies that are offset by more than 0.5-inch total, including design and production tolerances, need to be addressed as being injurious objects within the striking radius of the head,

e.g., by padding the armrest.

(G) Armrests that are padded (using appropriate padding material as described in paragraph 81b(5) of this AC) must have the padding cover the length of the armrest that is encompassed by 35-inch and smaller head strike arcs. Bounded armrests, where the seatback(s) have the breakover feature locked out, need not be padded to encompass the entire 35-inch head strike arc because the seatbacks prevent the contact of the armrest on the forward side of the seatback(s). Therefore, these armrests need only be padded to the forward edge of the seatback(s) in their upright position achieved after the small hand force is applied to the seatback. Portions of the armrest surface that cannot be contacted by the head are not required to be padded, e.g., the lower (or under) surface of a curved armrest.

(H) As an alternative to the use of padding, surfaces within the striking radius of the head that translate out of the striking radius under a nominal (10 pound) load may be considered to provide adequate protection, e.g., armrests that have been pivoted upward, which pivot downward out of the head strike arc under the nominal load. During an evaluation of this feature, the load must be applied in a direction that approximates the motion of a seated and belted occupant in the seat aft of the armrest under crash conditions.

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**117 FIGURE 86-3 ARMREST OFFSET**

**FIGURE 86-4 NON-EXPOSED AND EXPOSED ARMREST**

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(12) Paragraph (d). The seat back may serve as a firm hand hold. Since many seats are capable of breaking over, the breakover load must be adequate to be considered firm. A load of 25 lbs minimum, acting horizontally, is considered adequate when applied at the top center of the seat back. (Refer to paragraph 411b.(10) for maximum breakover force.) Very large seat pitches (in excess of 65-inches) may not permit the seatbacks to act as a handhold. This is due to both distance between the seatbacks and the capability of the seats to have very large amounts of recline. In this case, it may be necessary to install supplementary features to serve as handholds.

Seat mounted headrests that move relative to the seatback do not need to be assessed for their ability to provide a firm handhold, provided the seatback remains available for use as a handhold, and meets the criteria identified above. Other interior features such as class dividers, closets and other monuments may also serve as acceptable handholds if they provide a surface for occupants to push against to steady themselves while moving about the cabin interior.

(Amendment 25-0)

(13) Paragraph (f). Each berth installation should include a seat belt located approximately at the occupant's pelvis. For a berth installation with the feet facing forward, a bag, enclosing the legs to catch the upper torso when subjected to 9g, would be satisfactory in lieu of a padded end board. If the head is facing forward, a strap over each shoulder configuration would be satisfactory. If the berth is side facing, a padded side board or two belts, located approximately at the thighs and approximately at the chest, would be satisfactory.

(Amendment 25-0)

(14) Paragraphs (g) and (h). The combined safety belt and shoulder harness should consist of a standard safety belt and a shoulder harness with a strap over each shoulder. The shoulder harness straps should be as close to the neck as possible and may join behind the neck or each strap may attach separately to structure. In the front, the shoulder harness straps should attach to the buckle or safety belt near the buckle. Some harness geometries have been found acceptable where the shoulder harness straps are attached to the seat belt attach fittings. Ideally, the buckle should be located near the center of the torso. The single point release should be one action in which both the safety belt and shoulder harness are released simultaneously. The means provided to secure each combined safety belt and harness should be designed so that the belt and harness strap material does not get repeatedly creased over a long period of wear.

(Amendment 25-51)

(15) Paragraphs (g), (h) and (j). Refer to AC 25.785-lA, Flight Attendant Seat and Torso Restraint System Installations, dated 1/6/94, for additional acceptable means of compliance. (Amendment 25-51)

(16) Paragraph (h). Flight attendant seats that are provided for the airplane configuration should be installed near the approved floor level emergency exits. This should not be interpreted as a requirement to install flight attendant seats at each floor level exit. "Near" is defined in AC 25.785-1A. (Amendment 25-0)

(17) Paragraph (i). In order to reduce the deceleration "g" forces on occupants, some forward facing seats are designed to collapse. Usually, the design incorporates collapsible front

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119 legs. Such is acceptable if the collapse does not occur until a minimum of 8g has been applied.

After the collapse has occurred, the ultimate load of 9g should be applied and maintained for the required three seconds. The activation of the energy absorbing feature should not result in occupant injury. Various dimensions, such as 35-inches to injurious object clearance, aisle width and clearance, and interference with exits, should be evaluated before and after activation of the energy absorbing feature. Required dimensional clearances, such as aisles, passageways, flight attendant assist spaces, exit opening envelopes, and clearance between seats and potentially injurious surfaces must be maintained after the energy-absorbing feature is activated. The final position of the seat should not trap occupants. When testing a seat to demonstrate compliance with the static requirements of § 25.561, the testing should be conducted with an occupant center of gravity (CG) location as defined in NAS 809 (referenced in Technical Standard Order (TSO) C39) and AS8049 (referenced in the current version of TSO-C127). This CG location should be utilized in any airplane interface load analysis conducted. (Amendment 25-0)

(18) Paragraph (i). Technical Standard Order (TSO)-C22 is applicable only to seat belts. Technical Standard Order C114 may be applicable to shoulder harnesses, or they may be approved as part of the airplane. Sled tests with anthropomorphic dummies have shown that shoulder harness loads for forward facing seats can vary between 40 percent and 60 percent of the total load. Therefore, it is acceptable to substantiate a shoulder harness load of 60 percent (Refer to AC 25.785-1A, “Flight Attendant Seat and Torso Restraint System Installations,” dated 1/6/94): 0.6x9gx170 lbs = 918 lbs. If the seat belt is not approved under TSO-C22 or later revision, it should be approved as part of the airplane. The seat belt should be substantiated for 100 percent of the occupant load: 9g x 170 lbs = 1530 lbs. This is necessary even if the shoulder harness is permanently attached to the seat belt, since it is usually possible to utilize the seat belt without using the shoulder harness. The l.33 fitting factor is applicable to these configurations.

(Amendment 25-0)

(19) Paragraph (i)(1)(i). A seat is normally approved to TSO-C39 or later revision.

This approval may not account for the critical load when occupied by less than maximum occupants, e.g., one or two occupants in a triple seat. In some seat designs, occupancy by less than the maximum could be a critical design load for a particular structural member. All possible combinations of seat place occupancy should be substantiated by test or analysis. The loads for underseat baggage restraint systems attached to the seat should be added to seat loads.

Refer to § 25.787 guidance for underseat baggage criteria. This can be done by the TSO manufacturer when doing the TSO substantiation or by the applicant who is installing the seat.

(Amendment 25-0)

(20) Paragraph (i)(3). The l.33 factor is only required to be applied to the stated attachments. This factor should be applied to both ends of each attachment, (i.e., the seat end and the airplane end) and the fitting. If the applicant wishes to test the entire seat and belt assembly to this l.33 factor, it is satisfactory. (Amendment 25-0)

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87. AMENDMENT 25-72, Effective August 20, 1990.

a. Regulation.

[(a) A seat (or berth for a nonambulant person) must be provided for each occupant who has reached his or her second birthday.

(b) Each seat, berth, safety belt, harness, and adjacent part of the airplane at each station designated as occupiable during takeoff and landing must be designed so that a person making proper use of these facilities will not suffer serious injury in an emergency landing as a result of the inertia forces specified in §§ 25.561 and 25.562.

(c) Each seat or berth must be approved.

(d) Each occupant of a seat that makes more than an 18° angle with the vertical plane containing the airplane centerline must be protected from head injury by a safety belt and an energy absorbing rest that will support the arms, shoulders, head, and spine, or by a safety belt and shoulder harness that will prevent the head from contacting any injurious object. Each occupant of any other seat must be protected from head injury by a safety belt and, as appropriate to the type, location, and angle of facing of each seat, by one or more of the following:

(1) A shoulder harness that will prevent the head from contacting any injurious object.

(2) The elimination of any injurious object within striking radius of the head.

(3) An energy absorbing rest that will support the arms, shoulders, head, and spine.

(e) Each berth must be designed so that the forward part has a padded end board, canvas diaphragm, or equivalent means, that can withstand the static load reaction of the occupant when subjected to the forward inertia force specified in § 25.561. Berth must be free from corners and protuberances likely to cause injury to a person occupying the berth during emergency conditions.

(f) Each seat or berth, and its supporting structure, and each safety belt or harness and its anchorage must be designed for an occupant weight of 170 pounds, considering the maximum load factors, inertia forces, and reactions among the occupant, seat, safety belt, and harness for each relevant flight and ground load condition (including the emergency landing conditions prescribed in § 25.561). In addition-

(1) The structural analysis and testing of the seats, berths, and their supporting structures may be determined by assuming that the critical load in the forward, sideward, downward, upward, and rearward directions (as determined from the prescribed flight, ground, and emergency landing conditions) acts separately or using

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121 selected combinations of loads if the required strength in each specified direction is substantiated. The forward load factor need not be applied to safety belts for berths.

(2) Each pilot seat must be designed for the reactions resulting from the application of the pilot forces prescribed in § 25.395.

(3) The inertia forces specified in § 25.561 must be multiplied by a factor of 1.33 (instead of the fitting factor prescribed in § 25.625) in determining the strength of the attachment of each seat to the structure and each belt or harness to the seat or structure.

(g) Each seat at a flight deck station must have a restraint system consisting of a combined safety belt and shoulder harness with a single-point release that permits the flight deck occupant, when seated with the restraint system fastened, to perform all of the occupant's necessary flight deck functions. There must be a means to secure each combined restraint system when not in use to prevent interference with the operation of the airplane and with rapid egress in an emergency.

(h) Each seat located in the passenger compartment and designated for use during takeoff and landing by a flight attendant required by the operating rules of this chapter must be:

(1) Near a required floor level emergency exit, except that another location if the emergency egress of passengers would be enhanced with that location. A flight attendant seat must be located adjacent to each Type A emergency exit. Other flight attendant seats must be evenly distributed among the required floor level emergency exits to the extent feasible.

(2) To the extent possible, without compromising proximity to a required floor level emergency exit, located to provide a direct view of the cabin area for which the flight attendant is responsible.

(3) Positioned so that the seat will not interfere with the use of a passageway or exit when the seat is not in use.

(4) Located to minimize the probability that occupants would suffer injury by being struck by items dislodged from service areas, stowage compartments, or service equipment.

(5) Either forward or rearward facing with an energy absorbing rest that is designed to support the arms, shoulders, head, and spine.

(6) Equipped with a restraint system consisting of a combined safety belt and shoulder harness unit with a single point release. There must be means to secure each restraint system when not in use to prevent interference with rapid egress in an emergency.

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(i) Each safety belt must be equipped with a metal to metal latching device.

(j) If the seat backs do not provide a firm handhold, there must be a handgrip or rail along each aisle to enable persons to steady themselves while using the aisles in moderately rough air.

(k) Each projecting object that would injure persons seated or moving about the airplane in normal flight must be padded.

(l) Each forward observer's seat required by the operating rules must be shown to be suitable for use in conducting the necessary enroute inspection.]

b. Guidance.

(1) Refer to Advisory Circular 25.562-1B dated 1/10/2006, Dynamic Evaluation of Seat Restraint Systems & Occupant Protection on Transport Airplanes, dated 1/19/96, for detailed guidance concerning this amendment. (Amendment 25-64)

(2) Paragraph (b). Compliance with § 25.785(b) can be demonstrated using the tests required by § 25.562(b), and showing compliance with the associated injury criteria, for those objects that are assessed in those tests. However, because the tests specified in § 25.562 are limited to certain conditions, they may not address all areas that could be injurious, either in flight, or in an emergency landing. For this reason, simply showing that an object is outside the headstrike envelope produced in a dynamic test in accordance with § 25.562 is not sufficient to show compliance with 25.785(b). Objects may, in fact, require delethalization, even though they are not struck in a dynamic test. (Amendment 25-64)

(3) Paragraph (b). In order for the seat belt to be effective, it should be positioned to lay across the hip bone and ideally be about 45 degrees from the horizontal. An acceptable range for this angle is 35 degrees to 55 degrees. An acceptable range for the shoulder harness is 30 degrees above to 5 degrees below the horizontal. Refer to ACs 25.785-1A, “Flight Attendant Seat and Torso Restraint System Installations,” dated 1/6/94, and 43.13-1A, “Acceptable Methods, Techniques, and Practices-Aircraft Inspection and Repair (with Errata Sheet),” dated 4/17/72, for related guidance. When testing a seat to demonstrate compliance with the static requirements of § 25.561, the testing should be conducted with an occupant center of gravity (CG) location as defined in NAS 809 (referenced in Technical Standard Order (TSO) C39) and AS8049 (referenced in the current version of TSO-C127). This CG location should be utilized in any airplane interface load analysis conducted. (Amendment 25-0)

(4) Paragraphs (b) and (d). The FAA issued policy memorandum ANM-03-115-28, dated October 2, 2003, and titled “Policy Statement on Use of Surrogate Parts When Evaluating Seatbacks and Seatback Mounted Accessories for Compliance with §§ 25.562(c) (5) and

25.785(b) and (d). This policy may be used with any test method used to demonstrate compliance with blunt force trauma for items mounted on the seatback. The policy is applicable to Amendment 25-72, for §§ 25.785 (b) and (d) as follows: (Amendment 25-0)

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(i) In many row-to-row seat configurations, seatback mounted accessories are installed within the head paths of forward facing seated occupants. In order to demonstrate compliance with the aforementioned requirements, tests are conducted to assess the injury potential of these seatbacks and accessories. This policy only addresses head injury caused by blunt trauma. It does not address parts that become loose or sharp projections that are formed that may be injurious to a seated occupant during a head impact.

(ii) The types of tests that are conducted for blunt trauma assessments are dependant on the certification basis of the airplane. Airplane certification bases, which include § 25.562(c)(5), require that protection be provided so that a head impact does not result in a HIC greater than 1,000 units under the dynamic test conditions specified in § 25.562(b). Typically, airplanes which do not have § 25.562(c)(5) in their certification basis, must still comply with the more general occupant protection requirements of §§ 25.785(b) and (d). Sections 25.785(b) and

(d) require that a seat be designed so that an occupant would not suffer “serious injury” in an emergency landing and that injurious objects within the striking radius of the head be eliminated.

As a result, seatbacks/accessories on these airplanes must be evaluated to ensure that an occupant would not suffer serious head injury from blunt trauma.

(iii) Currently, blunt trauma tests are conducted with seatback mounted accessories represented by actual production parts or parts that are similar in construction to the production parts. Industry has informed the FAA that certification delays occur due to the unavailability of actual accessories for testing. In addition, accessories are typically damaged during certification tests and are not usable in subsequent tests or for installation and delivery to a customer. Several specimens of the same part are repeatedly used, and damaged, during certification tests due to test failures or substantiating alternate seatback designs. This results in significant costs to manufacturers and customers.

(iv) The FAA has determined that it is acceptable to use a surrogate test article made of 6061-T4 aluminum which meets the criteria below in lieu of an accessory for demonstrating compliance with §§ 25.562(c)(5) and 25.785(b) and (d) for blunt trauma assessments. An exception to the use of the surrogate test article occurs when the accessory is more rigid (deflects less and absorbs less energy during impact) than the plate defined in this AC. In that case, the accessory should be used in the test(s) and not a surrogate test article. The following criteria are applicable when using a surrogate test article during blunt trauma testing in accordance with §§ 25.562(c)(5) and 25.785(b) and (d):

(A) The surrogate part should be fabricated from 6061-T4 aluminum and have a minimum thickness of 0.238-inch (i.e., 0.25-inch minus a 0.012-inch manufacturing tolerance) at all locations. The length and width of the surrogate part should equal, within tolerances, the length and width of the actual part, respectively.

(B) The exposed surface of the surrogate part that will be impacted should be flat. That is, it is not required to have the contour of the accessory’s exposed surface represented by the surrogate part. Note that this is based on typical accessory installations which are essentially mounted flush with the seatback and have a generally homogeneous contact area.

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124 Small variations in the surface due to the contour of plastic parts may be ignored. Designs that differ from this (e.g., a design with an exposed structural protrusion) might require the exposed surface of the actual part to be represented in order to adequately assess head injury potential.

(C) The weight of the surrogate part, and additional ballast if needed, should be ±10 percent of the weight of the actual part.

(D) The surrogate part should be located on the seatback in the same place

(i.e., within manufacturing tolerances for mounting the actual part) where the actual part would be located in terms of the x and y coordinates in Figure 87-1. The surrogate part should be located such that the surface, which will be contacted during the test, is at the same location (i.e., within manufacturing tolerances for mounting the actual part) where the actual part would be in terms of the z coordinate. (Refer to figure 87-1.)

(E) The surrogate part should be attached to the seat by the final production hardware or a conservative representation of the final production hardware. For substantiating blunt trauma requirements, a conservative representation of the attachment hardware would be at least as rigid as the actual hardware. The surrogate part should be mounted so that it would not move farther or faster, with respect to the seatback, than the actual part during the test. Note that a conservative representation of the attachment hardware for determining HIC may not adequately represent the attachment hardware for substantiating it to § 25.562 loads. However, if the attachment hardware is adequately represented for substantiating it to § 25.562 loads, the test using a surrogate part may also be used to demonstrate that the attachment hardware will retain the actual accessory under § 25.562 loads.

(F) If the surrogate part cracks during a test, the test results are invalid.

(G) A surrogate part made of a material and thickness other than 6061-T4 aluminum in a nominal thickness of 0.25-inch may be used if an FAA Aircraft Certification Office finds that it is at least as rigid (i.e., it deflects less and absorbs less energy during the test).

Surrogate test articles which are less rigid than the aluminum surrogate part defined above are not addressed in this AC. If an applicant desires to use a surrogate part which is less rigid, its use should be approved through the issue paper process (or equivalent) or by an FAA policy memorandum. Testing may be required to determine the acceptability of these less rigid surrogate parts.

### Page 141 (OCR)

FIGURE 87-1 SURROGATE PART INSTALLED ON SEATBACK Surrogate part installed on the back side of the seatback in lieu of the actual accessory.

The x and y axes are in the plane of the backside of the seatback 125

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(5) Paragraphs (b) and (d). The FAA issued policy memorandum ANM-03-115-31, dated May 9, 2005, and titled “Policy Statement on Conducting Component Level Tests to Demonstrate Compliance with §§ 25.785(b) and (d).” Appendix 13 of this AC contains the complete policy memorandum. Applicants may use the test methods described in Appendix 13 to demonstrate compliance with §§ 25.785(b) and (d) for both blunt force trauma and formation of post-impact sharp or injurious edges or features for items within the head strike zone as defined in figure 87-2. The policy is applicable to design certification projects whose certification basis includes Amendment 25-72, for §§ 25.785 (b) and (d). (Amendment 25-0)

(6) Paragraph (c). For sideward facing seats, this change removed the option of a safety belt, and eliminated the possibility of locating any injurious object within striking radius of the head. This option is still satisfactory for forward and aft facing seats. The "human cushion" or unpadded bulkhead concept is not an adequate energy absorbing rest and therefore does not comply with this amendment of the regulation. The shoulder harness may be a diagonal shoulder harness over the forward shoulder. (Amendment 25-15)

(7) Paragraph (d). The 18-degree requirement applies to both forward and aft facing seat installations. If the forward direction is considered as 0 degrees or 360 degrees of a circle, the segments from 18 degrees to 162 degrees and 198 degrees to 342 degrees are considered a side facing seat and the seat installation must comply with one of the two options stated in the regulation. (Amendment 25-20)

(8) Paragraph (d)(2). The striking radius of the head for a forward facing seat (head strike zone) is considered to be a zone whose length is bounded between an arc at the shoulder height of the 5th percentile female occupant (20.5-inches) and an arc at the limit of the head path (35-inches), whose centers are at the intersection of the plane of the uncompressed top of the seat bottom cushion with the plane of the uncompressed front of the back cushion; commonly referred to as the cushion reference point (CRP), as shown in figure 87-2. Previously this was referred to as seat reference point (SRP). However, with the advent of dynamic seat testing the definition for SRP was changed (refer to SAE ARP5526D). The head strike zone extends in the direction parallel to the airplane longitudinal axis. The width of the head strike zone is bounded by a vertical plane through the intersection of the centerlines of each armrest and the CRP as shown in figure 87-2. Typical installations to be considered are bulkheads, cabinets, tables, and passenger evacuation slide covers. The installation should not contain any pointed corners or sharp edges. The testing used to demonstrate that the installation is not injurious must take into account whether the system (e.g., seatback mounted telephone) is allowed to be used during taxi, takeoff and landing. If the system is allowed to be used during these phases of operation, the testing must consider the system in both the deployed and stowed position (e.g., seatback mounted telephone in or out of the cradle). If a surface or interior feature is located such that it is potentially hazardous in a combination of forward and side loads, it should be substantiated even if it might be slightly outside of the head strike zone. Any surface less than 18-inches above the floor need not be considered. Surfaces within the head strike zone may be padded with energy absorbing material, such as one inch of either Ensolite (Type AH, AHC, IV3, HHC or HH), Klegecell, or Airex 4070. Foam rubber is not satisfactory since it is an energy storing material. If the padding is easily removed, there should be acceptable placarding requiring the padding be in place during taxi, takeoff, and landing. Compliance with § 25.562(c)(5) can be used to show compliance to § 25.785(d)(2) for those areas struck by the ATD head during dynamic testing.

### Page 143 (OCR)

See AC 25.562-1B, "Dynamic Evaluation of Seat Restraint Systems and Occupant Protection on Transport Airplanes." (Amendment 25-72) FIGURE 87-2 HEAD STRIKE ZONE FOR § 25.785 Head Strike Zone

20.5 inch 35 inch arc arc CRP 18 inches ¡CRP Centerline 35 inch arc of Armrest Seat Axis Airplane Longitudinal Axis Centerline of Armrest Seat Axis ‚CRP Airplane Centerline Longitudinal Axis of Armrest 35 inch arc Centerline of Armrest 127

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(9) Paragraph (d)(2). A flat surface within the 35-inch head strike arc, such as a table or partition, may be tested to the criteria of Society of Automotive Engineers (SAE) J921 or the following criteria. Impact injury criteria is discussed in AC 21-22, Injury Criteria for Human Exposure to Impact. (Amendment 25-0)

(i) A 13-pound bowling ball may be used to simulate the head of a 170-pound person whose seat belt is fastened and is subjected to 9g. (Amendment 25-0)

(ii) The ball shall impact the surface with at least 2780-inch-pounds of energy.

(Amendment 25-0)

(iii) The attachments of the test article shall not fail completely. (Amendment 25-0)

(iv) No parts shall become loose or sharp projections be formed that would be hazardous to the passengers. (Amendment 25-0)

(v) The test article may deform locally. (Amendment 25-0)

(vi) The surface being tested should perform equal to or better than a previously approved surface. The intent of this comparative test method is to test similar items (e.g., a seatback that does not have a telephone with a seatback that has a telephone installed). This test method should not be used to compare a seatback to an armrest. (Amendment 25-0)

(10) Paragraph (d)(2). (Amendment 25-0)

(i) Some passenger seats are designed with armrests that pivot upward such that the armrest could protrude beyond the seatbacks resulting in a potentially hazardous condition to persons seated behind these seats. Armrests that are adequately delethalized or restricted such that they cannot protrude aft of either seatback in any position are acceptable. (Amendment 25-0)

(ii) Armrests that are offset can be within the headstrike path of an occupant to the rear. Armrests within the striking radius of the head that are:

(A) bounded on both sides of the armrest by the seat backs and are offset more than 2-inches from the armrests of the seat to the rear, or (B) forward of an additional (exposed) seat in the row behind it, such that the forward armrest is bounded on one side only are considered to be injurious objects. The head must be protected from these injurious objects by some additional means such as padding.

Armrests that are bounded only on one side and not offset from the armrest of the seat in the rear are not considered to be injurious objects. (Amendment 25-0)

(11) Paragraph (d)(2). The FAA issued policy memorandum 02-115-15, dated November 25, 2002, titled “New Policy with respect to compliance with § 25.785(d), Amendment 25-88, for certification of passenger seat armrests.” The policy in this

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129 memorandum may be used for demonstrating compliance with § 25.785(d)(2), Amendment 25- 72, and is provided below.

(i) Armrests that might possibly be struck by persons seated behind (aft of) them are characterized as “bounded” or “unbounded.” Bounded armrests are defined as follows:

(A) An armrest that has a seatback on both sides, with the distance between the structure of the adjacent seatbacks no greater than five inches, or (B) An armrest that has a seatback on one side and the airplane sidewall panel or a wall that is part of an airplane furnishing (e.g., galley, closet, lavatory) on the other side with the distance between the structure of the seatback and the panel/wall no greater than five inches.

(ii) For purposes of this AC, the structure of the seatback is considered to be the parts of the seatback with load carrying capability. It does not include upholstery material or soft foam installed for occupant comfort. In some seat designs there is a metal frame in the seatback that forms the support structure to which the foam and upholstery are used to provide the shape of the seatback. When measuring the distance between the structure of the adjacent seatbacks of no greater than five inches, the measurement would be between these metal or composite supports structures.

(iii) Unbounded armrests are those that do not meet either definition above.

Additionally, seat places that are located aft of unbounded armrests may be characterized as either “exposed” or “non-exposed.” The non-exposed seat place is typically an aisle seat place,

i.e., located adjacent to a passenger aisle (refer to figure 87-3). The exposed seat place is typically located where the number of seats in the row forward is different from that of the seat row aft. For example, near Type III overwing exits, many airplanes have a double seat installed inboard of the exit with an empty space between the seat and the exit. The seat row aft of the double seat has a triple seat (refer to figure 87-4). In figure 87-4, seat place “A” is an exposed seat place that makes the outboard armrest of the double seat an unbounded exposed armrest.

(iv) The definitions above apply to all armrests in the airplane as applicable. The existing policy contained in this AC paragraphs 81b(5) and 81b(7) are still applicable to the armrests identified in the new policy below.

(A) Note: The policy below addresses armrests within the 35-inch head strike arc and surfaces 18-inches and greater above the floor. Armrests outside the 35-inch head strike arc and armrest surfaces less than 18-inches above the floor are acceptable as defined in this AC paragraphs 81b(5) and 81b(7).

(B) An armrest is acceptable by inspection if the armrests of two consecutive

(i.e., one aft of the other) seat assemblies (seats need not be of the same part number) are offset no greater 0.5-inch total, including design and production tolerances.

(C) Bounded armrests and non-exposed unbounded armrests are acceptable if:

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(1) The armrests of two consecutive seat assemblies are offset greater than 0.5-inch but no greater than two (2)-inches total, including design, and production tolerances, and

(2) The breakover feature of the seatback(s) adjacent to the armrest in the forward seat assembly is (are) locked out.

(D) The seatback breakover feature may be locked out by any method that requires a tool to release the lock out provision. The lockout of the breakover feature must be effective for the seatback in the upright position used for taxi, takeoff, and landing. Seatbacks incorporating an energy absorbing feature to meet the HIC requirements of § 25.562 are considered to have the breakover lockout and are acceptable. Whatever the method of seatback breakover lock out, there typically is some movement of the seatback. This movement of the seatback is acceptable as long as when the seatback is moved to the worst case position by a small hand load applied to the top of the seatback, the armrest is still afforded protection by the seatback, with the end of the top of the armrest being forward of the aft side of the seatback.

(E) Bounded armrests and non-exposed unbounded armrests, where the offset is greater than two (2)-inches total, including design and production tolerances, need to be addressed as being injurious objects within the striking radius of the head, e.g., by padding the armrest.

(F) Exposed unbounded armrests; if the armrests of two consecutive seat assemblies that are offset by more than 0.5-inch total, including design and production tolerances, need to be addressed as being injurious objects within the striking radius of the head,

e.g., by padding the armrest.

(G) Armrests that are padded (using appropriate padding material as described in paragraph 81b(5) of this AC) must have the padding cover the length of the armrest that is encompassed by 35-inch and smaller head strike arcs. Bounded armrests, where the seatback(s) have the breakover feature locked out, need not be padded to encompass the entire 35-inch head strike arc because the seatbacks prevent the contact of the armrest on the forward side of the seatback(s). Therefore, these armrests need only be padded to the forward edge of the seatback(s) in their upright position achieved after the small hand force is applied to the seatback. Portions of the armrest surface that cannot be contacted by the head are not required to be padded, e.g., the lower (or under) surface of a curved armrest.

(H) As an alternative to the use of padding, surfaces within the striking radius of the head that translate out of the striking radius under a nominal (10 pound) load may be considered to provide adequate protection, e.g., armrests that have been pivoted upward, which pivot downward out of the head strike arc under the nominal load. During an evaluation of this feature, the load must be applied in a direction that approximates the motion of a seated and belted occupant in the seat aft of the armrest under crash conditions.

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**131 FIGURE 87-3 ARMREST OFFSET**

**FIGURE 87-4 NON-EXPOSED AND EXPOSED ARMREST**

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(12) Paragraph (e). Each berth installation should include a seat belt located approximately at the occupant's pelvis. For a berth installation with the feet facing forward, a bag, enclosing the legs to catch the upper torso when subjected to 9g, would be satisfactory in lieu of a padded end board. If the head is facing forward, a strap over each shoulder configuration would be satisfactory. If the berth is side facing, a padded side board or two belts, located approximately at the thighs and approximately at the chest, would be satisfactory.

(Amendment 25-0)

(13) Paragraph (f). In order to reduce the deceleration "g" forces on occupants, some forward facing seats are designed to collapse. Usually, the design incorporates collapsible front legs. Such is acceptable if the collapse does not occur until a minimum of 8g has been applied.

After the collapse has occurred, the ultimate load of 9g should be applied and maintained for the required three seconds. The activation of the energy absorbing feature should not result in occupant injury. Various dimensions, such as 35-inches to injurious object clearance, aisle width and clearance, and interference with exits, should be evaluated before and after activation of the energy absorbing feature. Required dimensional clearances, such as aisles, passageways, flight attendant assist spaces, exit opening envelopes, and clearance between seats and potentially injurious surfaces must be maintained after the energy-absorbing feature is activated. The final position of the seat should not trap occupants. When testing a seat to demonstrate compliance with the static requirements of § 25.561, the testing should be conducted with an occupant center of gravity (CG) location as defined in NAS 809 (referenced in Technical Standard Order (TSO) C39) and AS8049 (referenced in the current version of TSO-C127). This CG location should be utilized in any airplane interface load analysis conducted. (Amendment 25-0)

(14) Paragraph (f). Technical Standard Order (TSO)-C22 is applicable only to seat belts. Technical Standard Order C114 may be applicable to shoulder harnesses, or they may be approved as part of the airplane. Sled tests with anthropomorphic dummies have shown that shoulder harness loads for forward facing seats can vary between 40 percent and 60 percent of the total load. Therefore, it is acceptable to substantiate a shoulder harness load of 60 percent (Refer to AC 25.785-1A, “Flight Attendant Seat and Torso Restraint System Installations,” dated 1/6/94): 0.6x9gx170 lbs = 918 lbs. If the seat belt is not approved under TSO-C22 or later revision, it should be approved as part of the airplane. The seat belt should be substantiated for 100 percent of the occupant load: 9g x 170 lbs = 1530 lbs. This is necessary even if the shoulder harness is permanently attached to the seat belt, since it is usually possible to utilize the seat belt without using the shoulder harness. The l.33 fitting factor is applicable to these configurations.

(Amendment 25-0)

(15) Paragraph (f)(1)(i). A seat is normally approved to TSO-C39 or later revision.

This approval may not account for the critical load when occupied by less than maximum occupants, e.g., one or two occupants in a triple seat. In some seat designs, occupancy by less than the maximum could be a critical design load for a particular structural member. All possible combinations of seat place occupancy should be substantiated by test or analysis. The loads for underseat baggage restraint systems attached to the seat should be added to seat loads.

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133 Refer to § 25.787 guidance for underseat baggage criteria. This can be done by the TSO manufacturer when doing the TSO substantiation or by the applicant who is installing the seat.

(Amendment 25-0)

(16) Paragraph (f)(3). The l.33 factor is only required to be applied to the stated attachments. This factor should be applied to both ends of each attachment, (i.e., the seat end and the airplane end) and the fitting. If the applicant wishes to test the entire seat and belt assembly to this l.33 factor, it is satisfactory. (Amendment 25-0)

(17) Paragraphs (g) and (h). The combined safety belt and shoulder harness should consist of a standard safety belt and a shoulder harness with a strap over each shoulder. The shoulder harness straps should be as close to the neck as possible and may join behind the neck or each strap may attach separately to structure. In the front, the shoulder harness straps should attach to the buckle or safety belt near the buckle. Some harness geometries have been found acceptable where the shoulder harness straps are attached to the seat belt attach fittings. Ideally, the buckle should be located near the center of the torso. The single point release should be one action in which both the safety belt and shoulder harness are released simultaneously. The means provided to secure each combined safety belt and harness should be designed so that the belt and harness strap material does not get repeatedly creased over a long period of wear.

(Amendment 25-51)

(18) Paragraphs (g) and (h). Refer to AC 25.785-lA, Flight Attendant Seat and Torso Restraint System Installations, dated 1/6/94, for additional acceptable means of compliance.

(Amendment 25-51)

(19) Paragraph (h). Flight attendant seats that are provided for the airplane configuration should be installed near the approved floor level emergency exits. This should not be interpreted as a requirement to install flight attendant seats at each floor level exit. "Near" is defined in AC 25.785-1A. (Amendment 25-0)

(20) Paragraph (j). The seat back may serve as a firm hand hold. Since most seats are capable of breaking over, the breakover load must be adequate to be considered firm. A load of 25 lbs minimum, acting horizontally, is considered adequate when applied at the top center of the seat back. (Refer to paragraph 411b.(10) for maximum breakover force.) Very large seat pitches (in excess of 65-inches) may not permit the seatbacks to act as a handhold. This is due to both distance between the seatbacks and the capability of the seats to have very large amounts of recline. In this case, it may be necessary to install supplementary features to serve as handholds.

Seat mounted headrests that move relative to the seatback do not need to be assessed for their ability to provide a firm handhold, provided the seatback remains available for use as a handhold, and meets the criteria identified above. Other interior features such as class dividers, closets and other monuments may also serve as acceptable handholds if they provide a surface for occupants to push against to steady themselves while moving about the cabin interior.

(Amendment 25-0)

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88. AMENDMENT 25-88, Effective December 9, 1996.

a. Regulation.

(a) A seat (or berth for a nonambulant person) must be provided for each occupant who has reached his or her second birthday.

(b) Each seat, berth, safety belt, harness, and adjacent part of the airplane at each station designated as occupiable during takeoff and landing must be designed so that a person making proper use of these facilities will not suffer serious injury in an emergency landing as a result of the inertia forces specified in §§ 25.561 and 25.562.

(c) Each seat or berth must be approved.

(d) Each occupant of a seat that makes more than an 18° angle with the vertical plane containing the airplane centerline must be protected from head injury by a safety belt and an energy absorbing rest that will support the arms, shoulders, head, and spine, or by a safety belt and shoulder harness that will prevent the head from contacting any injurious object. Each occupant of any other seat must be protected from the head injury by a safety belt and, as appropriate to the type, location, and angle of facing of each seat, by one or more of the following:

(1) A shoulder harness that will prevent the head from contacting any injurious object.

(2) The elimination of any injurious object within striking radius of the head.

(3) An energy absorbing rest that will support the arms, shoulders, head, and spine.

(e) Each berth must be designed so that the forward part has a padded end board, canvas diaphragm, or equivalent means, that can withstand the static load reaction of the occupant when subjected to the forward inertia force specified in § 25.561.

Berths must be free from corners and protuberances likely to cause injury to a person occupying the berth during emergency conditions.

(f) Each seat or berth, and its supporting structure, and each safety belt or harness and its anchorage must be designed for an occupant weight of 170 pounds, considering the maximum load factors, inertia forces, and reactions among the occupant seat, safety belt, and harness for each relevant flight and ground load condition (including the emergency landing conditions prescribed in § 25.561). In addition-

(1) The structural analysis and testing of the seats, berths, and their supporting structures may be determined by assuming that the critical load in the forward, sideward, downward, upward, and rearward directions (as determined from the prescribed flight, ground, and emergency landing conditions) acts separately or using

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135 selected combinations of loads if the required strength in each specified direction is substantiated. The forward load factor need not be applied to safety belts for berths.

(2) Each pilot seat must be designed for the reactions resulting from the application of the pilot forces prescribed in § 25.395.

(3) The inertia forces specified in § 25.561 must be multiplied by a factor of 1.33 (instead of the fitting factor prescribed in § 25.625) in determining the strength of the attachment of each seat to the structure and each belt or harness to the seat or structure.

(g) Each seat at a flight deck station must have a restraint system consisting of a combined safety belt and shoulder harness with a single-point release that permits the flight deck occupant, when seated with the restraint system fastened, to perform all of the occupant's necessary flight deck functions. There must be a means to secure each combined restraint system when not in use to prevent interference with the operation of the airplane and with rapid egress in an emergency.

(h) Each seat located in the passenger compartment and designated for use during takeoff and landing by a flight attendant required by the operating rules of this chapter must be:

[(1) Near a required floor level emergency exit, except that another location is acceptable if the emergency egress of passengers would be enhanced with that location. A flight attendant seat must be located adjacent to each Type A or B emergency exit. Other flight attendant seats must be evenly distributed among the required floor-level emergency exits to the extent feasible.]

(2) To the extent possible, without compromising proximity to a required floor level emergency exit, located to provide a direct view of the cabin area for which the flight attendant is responsible.

(3) Positioned so that the seat will not interfere with the use of a passageway or exit when the seat is not in use.

(4) Located to minimize the probability that occupants would suffer injury by being struck by items dislodged from service areas, stowage compartments, or service equipment.

(5) Either forward or rearward facing with an energy absorbing rest that is designed to support the arms, shoulders, head, and spine.

(6) Equipped with a restraint system consisting of a combined safety belt and shoulder harness unit with a single point release. There must be means to secure each restraint system when not in use to prevent interference with rapid egress in an emergency.

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(i) Each safety belt must be equipped with a metal to metal latching device.

(j) If the seat backs do not provide a firm handhold, there must be a handgrip or rail along each aisle to enable persons to steady themselves while using the aisles in moderately rough air.

(k) Each projecting object that would injure persons seated or moving about the airplane in normal flight must be padded.

(l) Each forward observer's seat required by the operating rules must be shown to be suitable for use in conducting the necessary enroute inspection.

b. Guidance.

(1) Refer to AC 25.562-1B dated 1/10/2006, Dynamic Evaluation of Seat Restraint Systems & Occupant Protection on Transport Airplanes, dated 1/19/96, for detailed guidance concerning this amendment. (Amendment 25-64)

(2) Paragraph (b). Compliance with § 25.785(b) can be demonstrated using the tests required by § 25.562(b), and showing compliance with the associated injury criteria, for those objects that are assessed in those tests. However, because the tests specified in § 25.562 are limited to certain conditions, they may not address all areas that could be injurious, either in flight, or in an emergency landing. For this reason, simply showing that an object is outside the headstrike envelope produced in a dynamic test in accordance with § 25.562 is not sufficient to show compliance with 25.785(b). Objects may, in fact, require delethalization, even though they are not struck in a dynamic test. (Amendment 25-64)

(3) Paragraph (b). In order for the seat belt to be effective, it should be positioned to lay across the hip bone and ideally be about 45 degrees from the horizontal. An acceptable range for this angle is 35 degrees to 55 degrees. An acceptable range for the shoulder harness is 30 degrees above to 5 degrees below the horizontal. Refer to ACs 25.785-1A, “Flight Attendant Seat and Torso Restraint System Installations,” dated 1/6/94, and 43.13-1A, “Acceptable Methods, Techniques, and Practices-Aircraft Inspection and Repair (with Errata Sheet),” dated 4/17/72, for related guidance. When testing a seat to demonstrate compliance with the static requirements of § 25.561, the testing should be conducted with an occupant center of gravity (CG) location as defined in NAS 809 (referenced in Technical Standard Order (TSO) C39) and AS8049 (referenced in the current version of TSO-C127). This CG location should be utilized in any airplane interface load analysis conducted. (Amendment 25-0)

(4) Paragraphs (b) and (d). The FAA issued policy memorandum ANM-03-115-28, dated October 2, 2003, titled “Policy Statement on Use of Surrogate Parts When Evaluating Seatbacks and Seatback Mounted Accessories for Compliance with §§ 25.562(C)(5) and

25.785(b) and (d).” This policy may be used with any test method used to demonstrate compliance with blunt force trauma for items mounted on the seatback. The policy is applicable to Amendment 25-88, for §§ 25.785 (b) and (d) as follows: (Amendment 25-0)

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(i) In many row-to-row seat configurations, seatback mounted accessories are installed within the head paths of forward facing seated occupants. In order to demonstrate compliance with the aforementioned requirements, tests are conducted to assess the injury potential of these seatbacks and accessories. This policy only addresses head injury caused by blunt trauma. It does not address parts that become loose or sharp projections that are formed that may be injurious to a seated occupant during a head impact.

(ii) The types of tests that are conducted for blunt trauma assessments are dependant on the certification basis of the airplane. Airplane certification bases, which include § 25.562(c)(5), require that protection be provided so that a head impact does not result in a HIC greater than 1,000 units under the dynamic test conditions specified in § 25.562(b). Typically, airplanes which do not have § 25.562(c)(5) in their certification basis, must still comply with the more general occupant protection requirements of §§ 25.785(b) and (d). Sections 25.785(b) and

(d) require that a seat be designed so that an occupant would not suffer “serious injury” in an emergency landing and that injurious objects within the striking radius of the head be eliminated.

As a result, seatbacks/accessories on these airplanes must be evaluated to ensure that an occupant would not suffer serious head injury from blunt trauma.

(iii) Currently, blunt trauma tests are conducted with seatback mounted accessories represented by actual production parts or parts that are similar in construction to the production parts. Industry has informed the FAA that certification delays occur due to the unavailability of actual accessories for testing. In addition, accessories are typically damaged during certification tests and are not usable in subsequent tests or for installation and delivery to a customer. Several specimens of the same part are repeatedly used, and damaged, during certification tests due to test failures or substantiating alternate seatback designs. This results in significant costs to manufacturers and customers.

(iv) The FAA has determined that it is acceptable to use a surrogate test article made of 6061-T4 aluminum which meets the criteria below in lieu of an accessory for demonstrating compliance with §§ 25.562(c)(5) and 25.785(b) and (d) for blunt trauma assessments. An exception to the use of the surrogate test article occurs when the accessory is more rigid (deflects less and absorbs less energy during impact) than the plate defined in this AC. In that case, the accessory should be used in the test(s) and not a surrogate test article. The following criteria are applicable when using a surrogate test article during blunt trauma testing in accordance with §§ 25.562(c)(5) and 25.785(b) and (d):

(A) The surrogate part should be fabricated from 6061-T4 aluminum and have a minimum thickness of 0.238-inch (i.e., 0.25-inch minus a 0.012-inch manufacturing tolerance) at all locations. The length and width of the surrogate part should equal, within tolerances, the length and width of the actual part, respectively.

(B) The exposed surface of the surrogate part that will be impacted should be flat. That is, it is not required to have the contour of the accessory’s exposed surface represented by the surrogate part. Note that this is based on typical accessory installations which are essentially mounted flush with the seatback and have a generally homogeneous contact area.

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138 Small variations in the surface due to the contour of plastic parts may be ignored. Designs that differ from this (e.g., a design with an exposed structural protrusion) might require the exposed surface of the actual part to be represented in order to adequately assess head injury potential.

(C) The weight of the surrogate part, and additional ballast if needed, should be ±10 percent of the weight of the actual part.

(D) The surrogate part should be located on the seatback in the same place

(i.e., within manufacturing tolerances for mounting the actual part) where the actual part would be located in terms of the x and y coordinates in Figure 88-1. The surrogate part should be located such that the surface, which will be contacted during the test, is at the same location (i.e., within manufacturing tolerances for mounting the actual part) where the actual part would be in terms of the z coordinate (Refer to figure 88-1).

(E) The surrogate part should be attached to the seat by the final production hardware or a conservative representation of the final production hardware. For substantiating blunt trauma requirements, a conservative representation of the attachment hardware would be at least as rigid as the actual hardware. The surrogate part should be mounted so that it would not move farther or faster, with respect to the seatback, than the actual part during the test. Note that a conservative representation of the attachment hardware for determining HIC may not adequately represent the attachment hardware for substantiating it to § 25.562 loads. However, if the attachment hardware is adequately represented for substantiating it to § 25.562 loads, the test using a surrogate part may also be used to demonstrate that the attachment hardware will retain the actual accessory under § 25.562 loads.

(F) If the surrogate part cracks during a test, the test results are invalid.

(G) A surrogate part made of a material and thickness other than 6061-T4 aluminum in a nominal thickness of 0.25-inch may be used if an FAA Aircraft Certification Office finds that it is at least as rigid (i.e., it deflects less and absorbs less energy during the test).

Surrogate test articles which are less rigid than the aluminum surrogate part defined above are not addressed in this AC. If an applicant desires to use a surrogate part which is less rigid, its use should be approved through the issue paper process (or equivalent) or by an FAA policy memorandum. Testing may be required to determine the acceptability of these less rigid surrogate parts.

### Page 155 (OCR)

FIGURE 88-1 SURROGATE PART INSTALLED ON SEATBACK Surrogate part installed on the back side of the seatback in lieu of the actual accessory.

The x and y axes are in the plane of the backside of the seatback 139

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(5) Paragraphs (b) and (d). The FAA issued policy memorandum ANM-03-115-31, dated May 9, 2005, and titled “Policy Statement on Conducting Component Level Tests to Demonstrate Compliance with §§ 25.785(b) and (d).” Appendix 13 of this AC contains the complete policy memorandum. Applicants may use the test methods described in Appendix 13 to demonstrate compliance with §§ 25.785(b) and (d) for both blunt force trauma and formation of post-impact sharp or injurious edges or features for items within the head strike zone as defined in figure 88-2. The policy is applicable to design certification projects whose certification basis includes Amendment 25-88, for §§ 25.785 (b) and (d). (Amendment 25-0)

(6) Paragraph (c). For sideward facing seats, this change removed the option of a safety belt, and eliminated the possibility of locating any injurious object within striking radius of the head. This option is still satisfactory for forward and aft facing seats. The "human cushion" or unpadded bulkhead concept is not an adequate energy absorbing rest and therefore does not comply with this amendment of the regulation. The shoulder harness may be a diagonal shoulder harness over the forward shoulder. (Amendment 25-15)

(7) Paragraph (d). The 18-degree requirement applies to both forward and aft facing seat installations. If the forward direction is considered as 0 degrees or 360 degrees of a circle, the segments from 18 degrees to 162 degrees and 198 degrees to 342 degrees are considered a side facing seat and the seat installation must comply with one of the two options stated in the regulation. (Amendment 25-20)

(8) Paragraph (d)(2). The striking radius of the head for a forward facing seat (head strike zone) is considered to be a zone whose length is bounded between an arc at the shoulder height of the 5th percentile female occupant (20.5-inches) and an arc at the limit of the head path (35-inches), whose centers are at the intersection of the plane of the uncompressed top of the seat bottom cushion with the plane of the uncompressed front of the back cushion; commonly referred to as the cushion reference point (CRP), as shown in figure 88-2. Previously this was referred to as seat reference point (SRP). However, with the advent of dynamic seat testing the definition for SRP was changed (refer to SAE ARP5526D). The head strike zone extends in the direction parallel to the airplane longitudinal axis. The width of the head strike zone is bounded by a vertical plane through the intersection of the centerlines of each armrest and the CRP as shown in figure 88-2. Typical installations to be considered are bulkheads, cabinets, tables, and passenger evacuation slide covers. The installation should not contain any pointed corners or sharp edges. The testing used to demonstrate that the installation is not injurious must take into account whether the system (e.g., seatback mounted telephone) is allowed to be used during taxi, takeoff and landing. If the system is allowed to be used during these phases of operation, the testing must consider the system in both the deployed and stowed position (e.g., seatback mounted telephone in or out of the cradle). If a surface or interior feature is located such that it is potentially hazardous in a combination of forward and side loads, it should be substantiated even if it might be slightly outside of the head strike zone. Any surface less than 18-inches above the floor need not be considered. Surfaces within the head strike zone may be padded with energy absorbing material, such as one inch of either Ensolite (Type AH, AHC, IV3, HHC or HH), Klegecell, or Airex 4070. Foam rubber is not satisfactory since it is an energy storing material. If the padding is easily removed, there should be acceptable placarding requiring the padding be in place during taxi, takeoff, and landing. Compliance with § 25.562(c)(5) can be used to show compliance to § 25.785(d)(2) for those areas struck by the ATD head during dynamic testing.

### Page 157 (OCR)

See AC 25.562-1B, "Dynamic Evaluation of Seat Restraint Systems and Occupant Protection on Transport Airplanes." (Amendment 25-72) FIGURE 88-2 HEAD STRIKE ZONE FOR § 25.785 Head Strike Zone

20.5 inch 35 inch arc arc CRP 18 inches ¡CRP Centerline 35 inch arc of Armrest Seat Axis Airplane Longitudinal Axis Centerline of Armrest Seat Axis ‚CRP Airplane Centerline Longitudinal Axis of Armrest 35 inch arc Centerline of Armrest 141

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(9) Paragraph (d)(2). A flat surface within the 35-inch head strike arc, such as a table or partition, may be tested to the criteria of Society of Automotive Engineers (SAE) J921 or the following criteria. Impact injury criteria is discussed in AC 21-22, Injury Criteria for Human Exposure to Impact. (Amendment 25-0)

(i) A 13-pound bowling ball may be used to simulate the head of a 170-pound person whose seat belt is fastened and is subjected to 9g. (Amendment 25-0)

(ii) The ball shall impact the surface with at least 2780-inch-pounds of energy.

(Amendment 25-0)

(iii) The attachments of the test article shall not fail completely. (Amendment 25-0)

(iv) No parts shall become loose or sharp projections be formed that would be hazardous to the passengers. (Amendment 25-0)

(v) The test article may deform locally. (Amendment 25-0)

(vi) The surface being tested should perform equal to or better than a previously approved surface. The intent of this comparative test method is to test similar items (e.g., a seatback that does not have a telephone with a seatback that has a telephone installed). This test method should not be used to compare a seatback to an armrest. (Amendment 25-0)

(10) Paragraph (d)(2). (Amendment 25-0)

(i) Some passenger seats are designed with armrests that pivot upward such that the armrest could protrude beyond the seatbacks resulting in a potentially hazardous condition to persons seated behind these seats. Armrests that are adequately delethalized or restricted such that they cannot protrude aft of either seatback in any position are acceptable. (Amendment 25-0)

(ii) Armrests that are offset can be within the headstrike path of an occupant to the rear. Armrests within the striking radius of the head that are:

(A) bounded on both sides of the armrest by the seat backs and are offset more than 2-inches from the armrests of the seat to the rear, or (B) forward of an additional (exposed) seat in the row behind it, such that the forward armrest is bounded on one side only are considered to be injurious objects. The head must be protected from these injurious objects by some additional means such as padding.

Armrests that are bounded only on one side and not offset from the armrest of the seat in the rear are not considered to be injurious objects. (Amendment 25-0)

(11) Paragraph (d)(2). The FAA issued policy memorandum 02-115-15, dated November 25, 2002, titled “New Policy with respect to compliance with § 25.785(d), Amendment 25-88, for certification of passenger seat armrests.” The policy in this

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143 memorandum may be used for demonstrating compliance with § 25.785(c)(2), Amendment 25- 88, and is provided below. (Amendment 25-0)

(i) Armrests that might possibly be struck by persons seated behind (aft of) them are characterized as “bounded” or “unbounded.” Bounded armrests are defined as follows:

(A) An armrest that has a seatback on both sides, with the distance between the structure of the adjacent seatbacks no greater than five inches, or (B) An armrest that has a seatback on one side and the airplane sidewall panel or a wall that is part of an airplane furnishing (e.g., galley, closet, lavatory) on the other side with the distance between the structure of the seatback and the panel/wall no greater than five inches.

(ii) For purposes of this AC, the structure of the seatback is considered to be the parts of the seatback with load carrying capability. It does not include upholstery material or soft foam installed for occupant comfort. In some seat designs there is a metal frame in the seatback that forms the support structure to which the foam and upholstery are used to provide the shape of the seatback. When measuring the distance between the structure of the adjacent seatbacks of no greater than five inches, the measurement would be between these metal or composite supports structures.

(iii) Unbounded armrests are those that do not meet either definition above.

Additionally, seat places that are located aft of unbounded armrests may be characterized as either “exposed” or “non-exposed.” The non-exposed seat place is typically an aisle seat place,

i.e., located adjacent to a passenger aisle (refer to figure 88-3). The exposed seat place is typically located where the number of seats in the row forward is different from that of the seat row aft. For example, near Type III overwing exits, many airplanes have a double seat installed inboard of the exit with an empty space between the seat and the exit. The seat row aft of the double seat has a triple seat (refer to figure 88-4). In figure 88-4, seat place “A” is an exposed seat place that makes the outboard armrest of the double seat an unbounded exposed armrest.

(iv) The definitions above apply to all armrests in the airplane as applicable. The existing policy contained in this AC paragraphs 81b(5) and 81b(7) are still applicable to the armrests identified in the new policy below.

(A) Note: The policy below addresses armrests within the 35-inch head strike arc and surfaces 18-inches and greater above the floor. Armrests outside the 35-inch head strike arc and armrest surfaces less than 18-inches above the floor are acceptable as defined in this AC paragraphs 81b(5) and 81b(7).

(B) An armrest is acceptable by inspection if the armrests of two consecutive

(i.e., one aft of the other) seat assemblies (seats need not be of the same part number) are offset no greater 0.5-inch total, including design and production tolerances.

(C) Bounded armrests and non-exposed unbounded armrests are acceptable if:

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(1) The armrests of two consecutive seat assemblies are offset greater than 0.5-inch but no greater than two (2)-inches total, including design, and production tolerances, and

(2) The breakover feature of the seatback(s) adjacent to the armrest in the forward seat assembly is (are) locked out.

(D) The seatback breakover feature may be locked out by any method that requires a tool to release the lock out provision. The lockout of the breakover feature must be effective for the seatback in the upright position used for taxi, takeoff, and landing. Seatbacks incorporating an energy absorbing feature to meet the HIC requirements of § 25.562 are considered to have the breakover lockout and are acceptable. Whatever the method of seatback breakover lock out, there typically is some movement of the seatback. This movement of the seatback is acceptable as long as when the seatback is moved to the worst case position by a small hand load applied to the top of the seatback, the armrest is still afforded protection by the seatback, with the end of the top of the armrest being forward of the aft side of the seatback.

(E) Bounded armrests and non-exposed unbounded armrests, where the offset is greater than two (2)-inches total, including design and production tolerances, need to be addressed as being injurious objects within the striking radius of the head, e.g., by padding the armrest.

(F) Exposed unbounded armrests; if the armrests of two consecutive seat assemblies that are offset by more than 0.5-inch total, including design and production tolerances, need to be addressed as being injurious objects within the striking radius of the head,

e.g., by padding the armrest.

(G) Armrests that are padded (using appropriate padding material as described in paragraph 81b(5) of this AC) must have the padding cover the length of the armrest that is encompassed by 35-inch and smaller head strike arcs. Bounded armrests, where the seatback(s) have the breakover feature locked out, need not be padded to encompass the entire 35-inch head strike arc because the seatbacks prevent the contact of the armrest on the forward side of the seatback(s). Therefore, these armrests need only be padded to the forward edge of the seatback(s) in their upright position achieved after the small hand force is applied to the seatback. Portions of the armrest surface that cannot be contacted by the head are not required to be padded, e.g., the lower (or under) surface of a curved armrest.

(H) As an alternative to the use of padding, surfaces within the striking radius of the head that translate out of the striking radius under a nominal (10 pound) load may be considered to provide adequate protection, e.g., armrests that have been pivoted upward, which pivot downward out of the head strike arc under the nominal load. During an evaluation of this feature, the load must be applied in a direction that approximates the motion of a seated and belted occupant in the seat aft of the armrest under crash conditions.

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**145 FIGURE 88-3 ARMREST OFFSET**

**FIGURE 88-4 NON-EXPOSED AND EXPOSED ARMREST**

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(12) Paragraph (e). Each berth installation should include a seat belt located approximately at the occupant's pelvis. For a berth installation with the feet facing forward, a bag, enclosing the legs to catch the upper torso when subjected to 9g, would be satisfactory in lieu of a padded end board. If the head is facing forward, a strap over each shoulder configuration would be satisfactory. If the berth is side facing, a padded side board or two belts, located approximately at the thighs and approximately at the chest, would be satisfactory.

(Amendment 25-0)

(13) Paragraph (f). In order to reduce the deceleration "g" forces on occupants, some forward facing seats are designed to collapse. Usually, the design incorporates collapsible front legs. Such is acceptable if the collapse does not occur until a minimum of 8g has been applied.

After the collapse has occurred, the ultimate load of 9g should be applied and maintained for the required three seconds. The activation of the energy absorbing feature should not result in occupant injury. Various dimensions, such as 35-inches to injurious object clearance, aisle width and clearance, and interference with exits, should be evaluated before and after activation of the energy absorbing feature. Required dimensional clearances, such as aisles, passageways, flight attendant assist spaces, exit opening envelopes, and clearance between seats and potentially injurious surfaces must be maintained after the energy-absorbing feature is activated. The final position of the seat should not trap occupants. When testing a seat to demonstrate compliance with the static requirements of § 25.561, the testing should be conducted with an occupant center of gravity (CG) location as defined in NAS 809 (referenced in Technical Standard Order (TSO) C39) and AS8049 (referenced in the current version of TSO-C127). This CG location should be utilized in any airplane interface load analysis conducted. (Amendment 25-0)

(14) Paragraph (f). Technical Standard Order (TSO)-C22 is applicable only to seat belts. Technical Standard Order C114 may be applicable to shoulder harnesses, or they may be approved as part of the airplane. Sled tests with anthropomorphic dummies have shown that shoulder harness loads for forward facing seats can vary between 40 percent and 60 percent of the total load. Therefore, it is acceptable to substantiate a shoulder harness load of 60 percent (Refer to AC 25.785-1A, “Flight Attendant Seat and Torso Restraint System Installations,” dated 1/6/94): 0.6x9gx170 lbs = 918 lbs. If the seat belt is not approved under TSO-C22 or later revision, it should be approved as part of the airplane. The seat belt should be substantiated for 100 percent of the occupant load: 9g x 170 lbs = 1530 lbs. This is necessary even if the shoulder harness is permanently attached to the seat belt, since it is usually possible to utilize the seat belt without using the shoulder harness. The l.33 fitting factor is applicable to these configurations.

(Amendment 25-0)

(15) Paragraph (f)(1)(i). A seat is normally approved to TSO-C39 or later revision.

This approval may not account for the critical load when occupied by less than maximum occupants, e.g., one or two occupants in a triple seat. In some seat designs, occupancy by less than the maximum could be a critical design load for a particular structural member. All possible combinations of seat place occupancy should be substantiated by test or analysis. The loads for underseat baggage restraint systems attached to the seat should be added to seat loads.

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147 Refer to § 25.787 guidance for underseat baggage criteria. This can be done by the TSO manufacturer when doing the TSO substantiation or by the applicant who is installing the seat.

(Amendment 25-0)

(16) Paragraph (f)(3). The l.33 factor is only required to be applied to the stated attachments. This factor should be applied to both ends of each attachment, (i.e., the seat end and the airplane end) and the fitting. If the applicant wishes to test the entire seat and belt assembly to this l.33 factor, it is satisfactory. (Amendment 25-0)

(17) Paragraphs (g) and (h). The combined safety belt and shoulder harness should consist of a standard safety belt and a shoulder harness with a strap over each shoulder. The shoulder harness straps should be as close to the neck as possible and may join behind the neck or each strap may attach separately to structure. In the front, the shoulder harness straps should attach to the buckle or safety belt near the buckle. Some harness geometries have been found acceptable where the shoulder harness straps are attached to the seat belt attach fittings. Ideally, the buckle should be located near the center of the torso. The single point release should be one action in which both the safety belt and shoulder harness are released simultaneously. The means provided to secure each combined safety belt and harness should be designed so that the belt and harness strap material does not get repeatedly creased over a long period of wear.

(Amendment 25-51)

(18) Paragraphs (g) and (h). Refer to AC 25.785-lA, Flight Attendant Seat and Torso Restraint System Installations, dated 1/6/94, for additional acceptable means of compliance.

(Amendment 25-51)

(19) Paragraph (h). Flight attendant seats that are provided for the airplane configuration should be installed near the approved floor level emergency exits. This should not be interpreted as a requirement to install for a flight attendant seats at each floor level exit.

"Near" is defined in AC 25.785-1A. (Amendment 25-0)

(20) Paragraph (h)(1). The intent of the use of the word “adjacent” is to require the flight attendant seat to be closer to the exit than if the word “near” were used. Typically, the flight attendant seat should be located immediately forward or aft of the passageway to the exit.

Consideration for an alternative location may be given if the flight attendant seat is located such that the flight attendant will be able to reach the exit faster than any passenger seated in the vicinity of the exit. (Amendment 25-46)

(21) Paragraph (j). The seat back may serve as a firm hand hold. Since most seats are capable of breaking over, the breakover load must be adequate to be considered firm. A load of 25 lbs minimum, acting horizontally, is considered adequate when applied at the top center of the seat back. (Refer to paragraph 411b.(10) for maximum breakover force.) Very large seat pitches (in excess of 65-inches) may not permit the seatbacks to act as a handhold. This is due to both distance between the seatbacks and the capability of the seats to have very large amounts of recline. In this case, it may be necessary to install supplementary features to serve as handholds.

Seat mounted headrests that move relative to the seatback do not need to be assessed for their ability to provide a firm handhold, provided the seatback remains available for use as a

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148 handhold, and meets the criteria identified above. Other interior features such as class dividers, closets and other monuments may also serve as acceptable handholds if they provide a surface for occupants to push against to steady themselves while moving about the cabin interior.

(Amendment 25-0)

89-100. [RESERVED]

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**149 SECTION 25.787 STOWAGE COMPARTMENTS**

**101. REGULATION IN EFFECT AT ADOPTION OF PART 25.**

a. Regulation.

(a) Each cargo and baggage compartment must be designed for its placarded maximum weight and contents and for the critical load distributions at the appropriate maximum load factors corresponding to the specified flight and ground load conditions, except the emergency landing conditions of § 25.561.

(b) There must be a means to prevent the contents in the compartments from becoming a hazard by shifting, under the loads specified in paragraph (a) of this section.

(c) There must be a means to protect the occupants from injury by the contents of any compartment, under the emergency landing conditions of § 25.561.

b. Guidance.

(1) Paragraph (a). Compartments placarded "No Stowage" need not have a weight limit placard. Compartments placarded "Emergency Equipment Only" need not have a weight limit placard provided the compartment is filled with designated emergency equipment that does not exceed the compartment's limit. (Refer to paragraphs 801b(1)(ii), 1041b(5) and 1101b(2).)

(Amendment 25-0)

(2) Paragraph (b). Baggage can be free if it can be shown that the forward barrier and cargo liner are able to restrain impact loads and the compartment is small enough to prevent significant shifts in center of gravity (c.g.). A 9g barrier net or other structure is required in all cargo versions if the cargo is not restrained to § 25.561 loads. In this case the cargo is restrained to flight and ground loads to prevent c.g. movement. If no 9g barrier net is used, the cargo is restrained to § 25.561 loads in an approved installation such as containers or pallets. (Refer to paragraph 1041b.(9).) (Amendment 25-0)

102. AMENDMENT 25-32, Effective May 1, 1972.

a. Regulation.

[(a) Each compartment for the stowage of cargo, baggage, carry-on articles, and equipment (such as life rafts), and any other stowage compartment must be designed for its placarded maximum weight of contents and for the critical load distribution at the appropriate maximum load factors corresponding to the specified flight and ground load conditions, and to the emergency landing conditions of § 25.561(b), except that the forces specified in the emergency landing conditions need not be

### Page 166

150 applied to compartments located below, or forward, of all occupants in the airplane.

If the airplane has a passenger seating configuration, excluding pilots seats, of 10 seats or more, each stowage compartment in the passenger cabin, except for underseat and overhead compartments for passenger convenience, must be completely enclosed.]

(b) There must be a means to prevent the contents in the compartments from becoming a hazard by shifting, under the loads specified in paragraph (a) of this section.

[(c) [Deleted.]]

b. Guidance. Paragraph (c) was deleted with the adoption of § 25.789.

(1) Paragraph (a). The intent for requiring completely enclosed stowage compartments is to provide more protection to occupants than that provided by restraint devices such as tiedown straps or webbing (with or without a curtain). A gap of 0.125-inch or less around the compartment door/drawer for operation of the compartment and manufacturing is acceptable.

These compartments are considered to be completely enclosed. (Amendment 25-32)

(2) Paragraph (a). Standard design criteria for underseat baggage restraint. (These criteria can be used for test or analysis purposes.) (Amendment 25-32)

(i) Forward restraint design criteria. (Amendment 25-32) (A) Load factor - 9g forward. (Amendment 25-32) (B) Basic baggage weight - 20 lbs per individual seat. (Amendment 25-32) (C) Bag dimension - 3 X 12 X 17-inches (assumed rigid). (Amendment 25-32) NOTE: These dimensions represent what is considered the most severe case and are not to be construed as the maximum baggage size which should be considered. The restraint device should be capable of restraining baggage of a size that can be stowed under the seat in the available space, but the weight need not be more than 20 lbs. (Amendment 25-32) (D) The bag surface upon which it rests should be assumed smooth so as to minimize any friction restraint. (Amendment 25-32) (E) The load (20 lbs X 9 g = 180 lbs) should be assumed applied through the bag with the seat mounted in its normal position. The 17 X 3-inch bag dimension should impinge on the restraint device unless the underseat dimensions are such that the test bag would protrude beyond the seat. In that case the 3 X 12-inch dimension should be used. (Amendment 25-32)

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151 (F) The critical load conditions for the underseat baggage restraints should be identified and demonstrated. (Amendment 25-32) (G) The bottom of the restraint system should be no more than 2 1/2-inches above the floor level of the airplane. The top of the system should be no less than 3-inches above the floor level of the airplane. (Amendment 25-32)

(ii) Side restraining design criteria. (Amendment 25-32) (A) The underseat baggage side restraint system should be capable of restraining a 20-pound rigid article per seat with the dimensions of 3 X 12 X 17-inches at 1.5g of side loading. (20 lbs X 1.5 g = 30 lbs per article.) (Amendment 25-32) (B) The side restraint system should be capable of restraining the article at

1.5g sidewards with the 17-inch dimension oriented fore and aft in the airplane. (Amendment 25-

32) (C) If the restraint system allows application of a footload, the system should be capable of withstanding a 300 pound standing load, applied in the most critical mode, without degrading either the basic forward load carrying capability or the side load carrying capabilities noted above or resulting in deformation causing the system to pose a tripping hazard.

(Amendment 25-32) (D) The system should be capable of withstanding the most critical loading condition due to asymmetrical loading of the system. (Amendment 25-32) (E) The bottom of the restraint system should be no more than 2 1/2-inches above the floor level of the airplane. The top of the system should be no less than 3-inches above the floor level of the airplane. The restraint system should extend a minimum of 8.75- inches aft from the aft face of the forward restraint portion of the system. (Amendment 25-32) (F) The side restraint system should not present a tripping hazard either for ingress to the seat or egress to the aisle or to the evacuation route. (Amendment 25-32) (G) The restraint system should not protrude into the aisle or evacuation route farther than the seat armrest on the aisle side. (Amendment 25-32)

(3) Paragraph (a). If overhead stowage compartments are intended for carriage of baggage, other than articles of loose clothing, they must be provided with approved restraining devices or doors (§ 121.589 (b)). (Amendment 25-32)

(4) Paragraph (a). The wording “a passenger seating configuration, excluding pilot seats, of 10 seats or more,” which was promulgated with the intent of being consistent with Amendment 23-10 to part 23, does not directly address seats intended for use by observers or flight attendants. Seats approved for use by observers or flight attendants are not included in the passenger seating configuration. Seats that have dual approval for occupancy by either

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152 crew/observers or passengers will be included in the passenger seating configuration.

(Amendment 25-32)

(5) Paragraph (a). Compartments placarded "No Stowage" need not have a weight limit placard. Compartments placarded "Emergency Equipment Only" need not have a weight limit placard provided the compartment is filled with designated emergency equipment that does not exceed the compartment's limit. (Refer to paragraphs 801b(1)(ii), 1041b(5) and 1101b(2).)

(Amendment 25-0)

(6) Paragraph (b). Baggage can be free if it can be shown that the forward barrier and cargo liner are able to restrain impact loads and the compartment is small enough to prevent significant shifts in center of gravity (c.g.). A 9g barrier net or other structure is required in all cargo versions if the cargo is not restrained to § 25.561 loads. In this case the cargo is restrained to flight and ground loads to prevent c.g. movement. If no 9g barrier net is used, the cargo is restrained to § 25.561 loads in an approved installation such as containers or pallets. (Refer to paragraph 1041b.(8).) (Amendment 25-0)

103. AMENDMENT 25-38, Effective February 1, 1977.

a. Regulation.

(a) Each compartment for the stowage of cargo, baggage, carry-on articles, and equipment (such as life rafts), and any other stowage compartment must be designed for its placarded maximum weight of contents and for the critical load distribution at the appropriate maximum load factors corresponding to the specified flight and ground load conditions, and to the emergency landing conditions of § 25.561(b), except that the forces specified in the emergency landing conditions need not be applied to compartments located below, or forward, of all occupants in the airplane.

If the airplane has a passenger seating configuration, excluding pilots seats, of 10 seats or more, each stowage compartment in the passenger cabin, except for underseat and overhead compartments for passenger convenience, must be completely enclosed.

(b) There must be a means to prevent the contents in the compartments from becoming a hazard by shifting, under the loads specified in paragraph (a) of this section.

[(c) If cargo compartment lamps are installed, each lamp must be installed so as to prevent contact between lamp bulb and cargo.]

b. Guidance.

(1) Paragraph (a). The intent for requiring completely enclosed stowage compartments is to provide more protection to occupants than that provided by restraint devices such as tiedown straps or webbing (with or without a curtain). A gap of 0.125-inch or less around the

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153 compartment door/drawer for operation of the compartment and manufacturing is acceptable.

These compartments are considered to be completely enclosed. (Amendment 25-32)

(2) Paragraph (a). Standard design criteria for underseat baggage restraint. (These criteria can be used for test or analysis purposes.) (Amendment 25-32)

(i) Forward restraint design criteria. (Amendment 25-32) (A) Load factor - 9g forward. (Amendment 25-32) (B) Basic baggage weight - 20 lbs per individual seat. (Amendment 25-32) (C) Bag dimension - 3 X 12 X 17-inches (assumed rigid). (Amendment 25-32) NOTE: These dimensions represent what is considered the most severe case and are not to be construed as the maximum baggage size which should be considered. The restraint device should be capable of restraining baggage of a size that can be stowed under the seat in the available space, but the weight need not be more than 20 lbs. (Amendment 25-32) (D) The bag surface upon which it rests should be assumed smooth so as to minimize any friction restraint. (Amendment 25-32) (E) The load (20 lbs X 9 g = 180 lbs) should be assumed applied through the bag with the seat mounted in its normal position. The 17 X 3-inch bag dimension should impinge on the restraint device unless the underseat dimensions are such that the test bag would protrude beyond the seat. In that case the 3 X 12-inch dimension should be used. (Amendment 25-32) (F) The critical load conditions for the underseat baggage restraints should be identified and demonstrated. (Amendment 25-32) (G) The bottom of the restraint system should be no more than 2 1/2-inches above the floor level of the airplane. The top of the system should be no less than 3-inches above the floor level of the airplane. (Amendment 25-32)

(ii) Side restraining design criteria. (Amendment 25-32) (A) The underseat baggage side restraint system should be capable of restraining a 20-pound rigid article per seat with the dimensions of 3 X 12 X 17-inches at 1.5g of side loading. (20 lbs X 1.5 g = 30 lbs per article.) (Amendment 25-32) (B) The side restraint system should be capable of restraining the article at

1.5g sidewards with the 17-inch dimension oriented fore and aft in the airplane. (Amendment 25-

32)

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154 (C) If the restraint system allows application of a footload, the system should be capable of withstanding a 300 pound standing load, applied in the most critical mode, without degrading either the basic forward load carrying capability or the side load carrying capabilities noted above or resulting in deformation causing the system to pose a tripping hazard.

(Amendment 25-32) (D) The system should be capable of withstanding the most critical loading condition due to asymmetrical loading of the system. (Amendment 25-32) (E) The bottom of the restraint system should be no more than 2 1/2-inches above the floor level of the airplane. The top of the system should be no less than 3-inches above the floor level of the airplane. The restraint system should extend a minimum of 8.75- inches aft from the aft face of the forward restraint portion of the system. (Amendment 25-32) (F) The side restraint system should not present a tripping hazard either for ingress to the seat or egress to the aisle or to the evacuation route. (Amendment 25-32) (G) The restraint system should not protrude into the aisle or evacuation route farther than the seat armrest on the aisle side. (Amendment 25-32)

(3) Paragraph (a). If overhead stowage compartments are intended for carriage of baggage, other than articles of loose clothing, they must be provided with approved restraining devices or doors (§ 121.589 (b)). (Amendment 25-32)

(4) Paragraph (a). The wording “a passenger seating configuration, excluding pilot seats, of 10 seats or more,” which was promulgated with the intent of being consistent with Amendment 23-10 to part 23, does not directly address seats intended for use by observers or flight attendants. Seats approved for use by observers or flight attendants are not included in the passenger seating configuration. Seats that have dual approval for occupancy by either crew/observers or passengers will be included in the passenger seating configuration.

(Amendment 25-32)

(5) Paragraph (a). Compartments placarded "No Stowage" need not have a weight limit placard. Compartments placarded "Emergency Equipment Only" need not have a weight limit placard provided the compartment is filled with designated emergency equipment that does not exceed the compartment's limit. (Refer to paragraphs 801b(1)(ii), 1041b(5) and 1101b(2).)

(Amendment 25-0)

(6) Paragraph (b). Baggage can be free if it can be shown that the forward barrier and cargo liner are able to restrain impact loads and the compartment is small enough to prevent significant shifts in center of gravity (c.g.). A 9g barrier net or other structure is required in all cargo versions if the cargo is not restrained to § 25.561 loads. In this case the cargo is restrained to flight and ground loads to prevent c.g. movement. If no 9g barrier net is used, the cargo is restrained to § 25.561 loads in an approved installation such as containers or pallets. (Refer to paragraph 1041b.(8).) (Amendment 25-0)

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104. AMENDMENT 25-51, Effective March 6, 1980.

a. Regulation.

(a) Each compartment for the stowage of cargo, baggage, carry-on articles, and equipment (such as life rafts), and any other stowage compartment must be designed for its placarded maximum weight of contents and for the critical load distribution at the appropriate maximum load factors corresponding to the specified flight and ground load conditions, and to the emergency landing conditions of § 25.561(b), except that the forces specified in the emergency landing conditions need not be applied to compartments located below, or forward, of all occupants in the airplane.

If the airplane has a passenger seating configuration, excluding pilots seats, of 10 seats or more, each stowage compartment in the passenger cabin, except for underseat and overhead compartments for passenger convenience, must be completely enclosed.

(b) There must be a means to prevent the contents in the compartments from becoming a hazard by shifting, under the loads specified in paragraph (a) of this section. [For stowage compartments in the passenger and crew cabin, if the means used is a latched door, the design must take into consideration the wear and deterioration expected in service.]

(c) If cargo compartment lamps are installed, each lamp must be installed so as to prevent contact between lamp bulb and cargo.

b. Guidance.

(1) Paragraph (a). The intent for requiring completely enclosed stowage compartments is to provide more protection to occupants than that provided by restraint devices such as tiedown straps or webbing (with or without a curtain). A gap of 0.125-inch or less around the compartment door/drawer for operation of the compartment and manufacturing is acceptable.

These compartments are considered to be completely enclosed. (Amendment 25-32)

(2) Paragraph (a). Standard design criteria for underseat baggage restraint. (These criteria can be used for test or analysis purposes.) (Amendment 25-32)

(i) Forward restraint design criteria. (Amendment 25-32) (A) Load factor - 9g forward. (Amendment 25-32) (B) Basic baggage weight - 20 lbs per individual seat. (Amendment 25-32) (C) Bag dimension - 3 X 12 X 17-inches (assumed rigid). (Amendment 25-32)

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156 NOTE: These dimensions represent what is considered the most severe case and are not to be construed as the maximum baggage size which should be considered. The restraint device should be capable of restraining baggage of a size that can be stowed under the seat in the available space, but the weight need not be more than 20 lbs. (Amendment 25-32) (D) The bag surface upon which it rests should be assumed smooth so as to minimize any friction restraint. (Amendment 25-32) (E) The load (20 lbs X 9 g = 180 lbs) should be assumed applied through the bag with the seat mounted in its normal position. The 17 X 3-inch bag dimension should impinge on the restraint device unless the underseat dimensions are such that the test bag would protrude beyond the seat. In that case the 3 X 12-inch dimension should be used. (Amendment 25-32) (F) The critical load conditions for the underseat baggage restraints should be identified and demonstrated. (Amendment 25-32) (G) The bottom of the restraint system should be no more than 2 1/2-inches above the floor level of the airplane. The top of the system should be no less than 3-inches above the floor level of the airplane. (Amendment 25-32)

(ii) Side restraining design criteria. (Amendment 25-32) (A) The underseat baggage side restraint system should be capable of restraining a 20-pound rigid article per seat with the dimensions of 3 X 12 X 17-inches at 1.5g of side loading. (20 lbs X 1.5 g = 30 lbs per article.) (Amendment 25-32) (B) The side restraint system should be capable of restraining the article at

1.5g sidewards with the 17-inch dimension oriented fore and aft in the airplane. (Amendment 25-

32) (C) If the restraint system allows application of a footload, the system should be capable of withstanding a 300 pound standing load, applied in the most critical mode, without degrading either the basic forward load carrying capability or the side load carrying capabilities noted above or resulting in deformation causing the system to pose a tripping hazard.

(Amendment 25-32) (D) The system should be capable of withstanding the most critical loading condition due to asymmetrical loading of the system. (Amendment 25-32) (E) The bottom of the restraint system should be no more than 2 1/2-inches above the floor level of the airplane. The top of the system should be no less than 3-inches above the floor level of the airplane. The restraint system should extend a minimum of 8.75- inches aft from the aft face of the forward restraint portion of the system. (Amendment 25-32)

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157 (F) The side restraint system should not present a tripping hazard either for ingress to the seat or egress to the aisle or to the evacuation route. (Amendment 25-32) (G) The restraint system should not protrude into the aisle or evacuation route farther than the seat armrest on the aisle side. (Amendment 25-32)

(3) Paragraph (a). If overhead stowage compartments are intended for carriage of baggage, other than articles of loose clothing, they must be provided with approved restraining devices or doors (§ 121.589 (b)). (Amendment 25-32)

(4) Paragraph (a). The wording “a passenger seating configuration, excluding pilot seats, of 10 seats or more,” which was promulgated with the intent of being consistent with Amendment 23-10 to part 23, does not directly address seats intended for use by observers or flight attendants. Seats approved for use by observers or flight attendants are not included in the passenger seating configuration. Seats that have dual approval for occupancy by either crew/observers or passengers will be included in the passenger seating configuration.

(Amendment 25-32)

(5) Paragraph (a). Compartments placarded "No Stowage" need not have a weight limit placard. Compartments placarded "Emergency Equipment Only" need not have a weight limit placard provided the compartment is filled with designated emergency equipment that does not exceed the compartment's limit. (Refer to paragraphs 801b(1)(ii), 1041b(5) and 1101b(2).)

(Amendment 25-0)

(6) Paragraph (b). Baggage can be free if it can be shown that the forward barrier and cargo liner are able to restrain impact loads and the compartment is small enough to prevent significant shifts in center of gravity (c.g.). A 9g barrier net or other structure is required in all cargo versions if the cargo is not restrained to § 25.561 loads. In this case the cargo is restrained to flight and ground loads to prevent c.g. movement. If no 9g barrier net is used, the cargo is restrained to § 25.561 loads in an approved installation such as containers or pallets. (Refer to paragraph 1041b.(8).) (Amendment 25-0)

(7) Paragraph (b). The intent of the last sentence of paragraph (b) is to prevent inadvertent opening of the latched doors of stowage compartments by specifically requiring that service wear and deterioration be considered in the design. This is not the same as the § 25.789 requirement that is directed to retention of items of mass subjected to maximum load factors.

The installation of acceptable dual latching devices, each of which can withstand the applicable loads, has been found to be one means to show compliance with this rule. Refer to AC 25.785- 1A, “Flight Attendant Seat and Torso Restraint System Installations,” dated 1/6/94, for additional information. (Amendment 25-51) 105 - 120. [RESERVED]

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