AC 25-17A

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 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

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

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.

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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,

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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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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]

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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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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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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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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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]