838 equipment meet the requirements of RTCA/DO-160D Section 21 Category M, then airplane ground testing to ensure no adverse interference with existing systems on the airplane is adequate, and no flight tests to demonstrate electromagnetic compatibility are required. Flight tests to demonstrate compatibility with other systems on the airplane would only be necessary if, a) the ground test demonstrates unresolved electromagnetic interference from the flightdeck door electrical and electronic equipment that may be due to the ground specific test configuration and not representative of in-flight conditions, or b) the RTCA/DO-160D Section 21 test results show significant RF emissions that exceed Category L within airplane communication, navigation or surveillance radio frequency bands. In these cases, the flight tests should assess any possible interference with radio systems required for continued safe flight and landing, such as auto-land, and Instrument Landing Systems during flightdeck door operations which potentially cause the most interference.
In general, flightdeck door systems have not been categorized as having catastrophic, hazardous or major failure conditions with respect to HIRF and lightning-induced transients. This must be confirmed by the specific flightdeck door installation applicant. If confirmed by the applicant, then § 25.1316 for system lightning protection and the HIRF special condition do not apply to the flightdeck door system.
Although the HIRF special condition generally will not be applied to the flightdeck door system, RF susceptibility tests for the flightdeck door electrical and electronic equipment are recommended as part of the compliance with §§ 25.1353(a) and
25.1431(c). Tests performed according to RTCA/DO-160D Section 20 Category T are acceptable.
All airplane wiring associated with the installation of the strengthened flightdeck door should comply with FAA policy statement, ANM-01-04, System Wiring Policy for Certification of Part 25 Airplanes, published in the Federal Register, February 5, 2002. The policy statement addresses wiring installation drawings, safety analysis and instructions for continued airworthiness. The safety analysis should specifically address interference on adjacent wiring and wire bundles in the airplane, especially any wire associated with systems required for safe flight and landing. For example, any potential interference with auto-land systems needs to be specifically addressed.
Although not specifically addressed in this memorandum, the following information is provided for reference and consideration on flightdeck door certification projects.
Video Camera Monitoring Systems: As part of the flightdeck door modification, applicants may choose to incorporate a video camera monitoring system in the door design. Policy and guidance relating to video systems used to view the cabin from the flightdeck is not addressed by this Memorandum, but is available in FAA Memorandum 01-111-196, dated October 5, 2001, “Interim Summary of Policy and Advisory Material Available for Use In the Certification of Cabin Mounted Video Cameras Systems with Flightdeck Displays on Title 14 CFR Part 25 Aircraft.”
839 For questions regarding the guidance in this memo, please contact Jeff Gardlin at (425) 227-2136, or via email at jeff.gardlin@faa.gov.
/s/ Vi Lipski Vi Lipski
DISTRIBUTION All Managers, Aircraft Certification Offices Manager, Aircraft Engineering Division, AIR-100 Manager, Transport Standards Staff, ANM-113 Manager, International Branch, ANM-116 Manager, SEA-AEG Manager, LGB-AEG
841 APPENDIX 12
ESTABLISHING THE MAXIMUM PASSENGER SEATING CAPACITY FOR AN
AIRPLANE MODEL For airplanes intended to be used in passenger carrying operations, the establishment of the maximum passenger seating capacity is one of the most important activities to be accomplished by the airplane manufacturer. The maximum passenger seating capacity is important because the commercial viability of an airplane is often dependent on its passenger seating capacity. The maximum passenger seating capacity must be established considering evacuation on land (emergency evacuation and exits requirements of §§ 25.803 and 25.807), and in the water (the ditching exit requirements of § 25.807). Additionally, if the airplane is proposed to be certified for extended overwater operations, compliance with the ditching requirements of § 25.801 must be demonstrated. If the airplane is to be utilized in extended overwater operations, compliance with all of the ditching requirements is necessary.
a. For an airplane not certified for extended overwater operations:
There are two or three requirements (depending on the maximum passenger seating capacity sought) that determine the maximum passenger seating capacity. For this appendix, the current amendment level of each regulation is noted. The requirements are as follows:
1. Type and number of emergency exits, § 25.807(g), Amendment 25-94. Paragraph (g) of § 25.807 establishes a maximum passenger seating capacity for land evacuation. Paragraph (g) stipulates the type (e.g., A, B, III) and number of exit pairs (except for ventral and tail cone exits) that need to be installed by adding up the “ratings” of each exit pair. There are some limitations regarding how exit types may be combined in getting the maximum passenger seating capacity, particularly for capacities up to 110.
2. Ditching emergency exits for passengers, § 25.807(i), Amendment 25-94. Paragraph (i) of § 25.807 establishes a maximum passenger seating capacity for water evacuation. Ditching exits are required whether or not the airplane is intended for extended overwater operations. It must be shown that, under reasonably probable water conditions, the flotation time and trim of the airplane will allow the occupants to leave the airplane. For airplanes not certified for extended overwater operations the flotation time and trim of the airplane must provide adequate time for the occupants to leave the airplane either into the water or on to the wing. For airplanes certified for extended overwater operations the flotation time and trim of the airplane must provide adequate time for the occupants to leave the airplane and enter the liferafts required by § 25.1415. Note that ditching exit capacity is based on individual exits, rather than exit pairs.
Type A exits are allowed 70 passengers per exit, whereas all other exits are allowed 35 passengers per exit.
3. Emergency evacuation demonstration, § 25.803(c), Amendment 25-72. This demonstration is conducted to ensure that the airplane, with its combination of exits, exit locations, seating and furnishing arrangements, etc., can be evacuated in a timely manner under
842 prescribed conditions. This demonstration is only required for airplanes with a maximum passenger seating capacity of 45 or more.
The maximum passenger seating capacity is determined by the smaller (smallest) number of passengers obtained under (a)(1), (a)(2) and, if applicable, (a)(3) above.
Example: if an airplane has 4 pairs of Type I exits, (a)(1) would allow a capacity of 180 passengers (4 x 45) and (a)(2) would allow 280 passengers (8 x 35), then the limit would be 180 passengers (the smaller of the two numbers). If a successful evacuation demonstration were conducted with 180 passengers, then the maximum passenger seating capacity would be 180. If, however, the manufacturer conducts the demonstration with only 165 passengers, then the maximum passenger seating capacity would be limited to 165.
b. For an airplane certified for extended overwater operations.
In addition to the requirements applicable for non-extended overwater operations certified airplanes, there is an additional requirement related to liferaft capacity, which may affect the total passenger seating capacity. Certification for ditching requires the installation of certain ditching equipment, in particular, liferafts, § 25.1415 (b), Amendment 25-82. These capacities liferaft include flight deck seats, flight attendant seats, and passengers’ seats that are occupiable for taxi, takeoff, and landing (TT&L) but does not include lap children (children who have not reached their second birthday who are seated on the lap of a passenger). Two calculations are necessary for determining the liferaft capacity of an airplane, as follows:
1. Maximum capacity of installed liferafts using there “rated” capacities (either remotely stowed, or integrated as part of emergency escape slides, known as “slide rafts”).
2. Maximum capacity of installed liferafts using their “overload” capacities but with one raft of the largest capacity considered to be unavailable.
Note: The rated and overload capacities for slide rafts and liferafts are established in Technical Standard Orders (TSO) C69 and C70 respectively.
The liferaft capacity is the smaller of the two capacities determined in (b)(1) and (b)(2) above.
This number is now compared to the number established for non-extended overwater airplanes.
If it is larger than the number established in (a), then the capacity remains as in (a). If it is smaller than the number established in (a), then the capacity is reduced to the number established in (b), during extended overwater operations.
Example: If an airplane has two pairs of Type A exits (one pair located at the forward end of the passenger cabin and the other pair located at the aft end of the passenger cabin), one pair of Type B exits, and one pair of Type I exits. The exit arrangement is ABIA. The maximum passenger seating capacity is as follows:
843 For (a)(1): two pairs of Type A gives a capacity of 220 (2 x 110), one pair of Type B exits 75, and one pair of Type I exits 45 for a total of 340 passengers.
For (a)(2): two pairs of Type A gives a capacity of 280 (4 x 70), one pair of Type B exits 70 (2 x
35), and one pair of Type I exits 70 (2 x 35) for a total of 420 passengers.
For (a)(3): the evacuation demonstration was successfully conducted with 340 passengers.
For (b)(1): the rated capacity of the slide rafts or liferafts installed on the airplane gives a capacity of for the forward pair of Type A exits 132 (2 x 66), aft pair of Type A exits 120 (2 x
60), for the pair of Type B exits 60 (2 x 30), and for the pair of Type I exits 60 (2 x 30) for a total of 372 occupants (flight deck seats, flight attendant seats, and passenger seats occupiable for TT&L).
For (b)(2): the largest slide raft or liferaft is one of the forward Type A exit side rafts. The remaining slide rafts and life rafts provide the overload capacity for the airplanes of for the forward pair of Type A exits 88 (1 x 88), aft pair of Type A exits 160 (2 x 80), for the pair of Type B exits 72 (2 x 36), and for the pair of Type I exits 90 (2 x 45) for a total of 410 occupants (flight deck seats, flight attendant seats, and passenger seats occupiable for TT&L).
Provided there are less than 32 crew seats (flight deck seats and flight attendant seats) the airplane is limited by (a)(1) and (a)(3).
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845 APPENDIX 13 FAA POLICY MEMO ANM-03-115-31, “POLICY STATEMENT ON CONDUCTING COMPONENT LEVEL TESTS TO DEMONSTRATE COMPLIANCE WITH §§ 25.785(B) AND (D)” DATED MAY 9, 2005
846 Memorandum U.S. Department of Transportation Federal Aviation Administration
Subject: INFORMATION: Policy Statement on Conducting Component Level Tests to Demonstrate Compliance with §§ 25.785(b) and (d)
Date: May 9, 2005
From: Manager, Transport Airplane Directorate, Aircraft Certification Service, ANM-100 Reply to Attn. of: ANM-03-115-31
To: Refer to Distribution Regulatory Reference: §§ 25.785(b) and (d)
The purpose of this memorandum is to provide Federal Aviation Administration (FAA) certification policy on conducting component level tests in order to demonstrate compliance with the requirements of §§ 25.785(b) and (d). The tests described herein provide a standardized approach by which each potentially injurious item located within the headstrike zone can be assessed for occupant injury potential. These test methods are the product of an Aviation Rulemaking Advisory Committee recommendation and are harmonized with the Joint Aviation Authorities (JAA) and Transport Canada.
Although this policy memorandum focuses primarily on describing component level tests for seatback mounted accessories installed within the striking radius of the head, the same test methodologies can be applied more generally to any surface or other items that may be potentially injurious and are located within the headstrike zone (e.g., escape slide bustles, and tables, etc.) that need to be addressed for compliance with §§ 25.785(b) and
(d).
In addition to §§ 25.785(b) and (d) blunt trauma requirements, some aircraft certification bases include the additional (and more stringent) requirements of § 25.562(c)(5). For these airplanes, protection must also be provided so that the head impact does not exceed a head injury criterion (HIC) measurement of 1000 units. The tests described herein do not address compliance with § 25.562(c)(5) HIC requirements.
Current Regulatory and Advisory Material Section 25.785(b), Amendment 25-88, requires that each seat, berth, safety belt, harness, and adjacent part of the airplane at each station designated as occupiable during takeoff and landing be designed so that a person making proper use of those facilities will not
847 suffer serious injury in an emergency landing as a result of inertia forces specified in §§ 25.561 and 25.562.
Section 25.785(d), Amendment 25-88, requires, in pertinent part, that each occupant of a forward or aft facing seat be protected from head injury by the elimination of injurious objects within the striking radius of the head.
These same occupant injury protection requirements have existed within § 25.785 (with the exception of reference to § 25.562 which was added by Amendment 25-64) since the adoption of part 25. As such, the policy contained within this memorandum can be utilized for demonstrating compliance with § 25.785 at all amendments. This policy cannot, however, be used in lieu of HIC testing for airplanes whose certification bases specifically require compliance with the requirements of § 25.562(c)(5). Attachment 1 provides additional information for determining how certification bases considerations affect the applicability of the tests described herein.
In order to demonstrate compliance with §§ 25.785(b) and (d), two injury mechanisms must be examined. The first consideration is blunt trauma injuries experienced by the occupant resulting from the crash loads. This policy memorandum describes three impact test methods that can be used to evaluate blunt trauma injuries. The second injury mechanism is sharp or injurious edges or features. Sharp or injurious edges or features could cause additional injury and thus impede occupants from exiting the airplanes after a crash; they are therefore not acceptable. They are not allowed as design features of airplane interiors, nor are they allowed to be formed as a result of the impact tests described within this policy memo. Both injury mechanisms (i.e., blunt trauma and sharp or injurious edges or features) must be successfully addressed in order to make a determination of compliance with the requirements of §§ 25.785(b) and (d).
Advisory Circular (AC) 25-17, paragraph 81b(4), as supplemented by FAA memorandum dated July 13, 1994, provided a method for demonstrating compliance with § 25.785 blunt trauma requirements using a comparative bowling ball test. This approach allowed an applicant to compare the characteristics of a new (i.e., unapproved) feature against a previously approved configuration. If the blunt trauma characteristics (measured by bowling ball impact accelerations) associated with the new feature were less severe than the previously approved configuration, they were considered acceptable. Advisory Circular 25-17 also described an assessment of the test article for sharp or injurious edges or features post-test.
We recognized that there were shortcomings with the bowling ball test policy as it was originally published. Because of these shortcomings, we noted in the July 13, 1994, memorandum our intent to develop more comprehensive policy on this subject. As such, this policy memorandum supersedes the guidance contained in AC 25-17, paragraphs 81b(4)(i) through b(4)(iv) regarding the bowling ball test pass/fail criteria and the subsequent FAA memorandum on this same subject, dated July 13, 1994.
848 Likewise, the impact device described in Society of Automotive Engineers (SAE) standard J921 essentially performs the same function as the bowling ball test and therefore is also no longer acceptable for demonstrating compliance with the requirements of §§ 25.785(b) and (d). This policy memorandum does not supersede any of the other methods of compliance pertaining to §§ 25.785(b) and (d) contained within AC 25-17. The remaining allowable methods of compliance described in AC 25-17 include padding potentially injurious surfaces and relocating objects outside of the headstrike zone.
Implementation of this new policy memorandum does not nullify any previously completed compliance determinations. However, all new compliance determinations should be made in accordance with this policy memorandum, the remaining methods of compliance identified in AC 25-17, or other methods of compliance established through the issue paper process.
Policy Sections 25.785(b) and (d) require that seatbacks, components mounted on the seatbacks (such as video monitors, telephones, cup holders, etc.), and any other objects located within the striking radius of the head, be designed to prevent serious injury to an occupant whose head would impact the objects as a result of the emergency landing inertia forces.
We have determined through 16g row to row dynamic tests that seatback accessories totaling less than three lbs do not exceed the performance criteria described below when installed in seatbacks that provide at least one inch of permanent deformation. Industry data indicate that “standard” airline passenger seatback designs generally provide more than one inch of permanent deformation. As a result, data substantiating seatback deformation is not required unless the seatback design contains unusual features that significantly increase the stiffness beyond that of traditional passenger seats.
If the seatback has been stiffened such that the one-inch permanent deformation assumption is questionable, testing may be required. For example, a business class pod seat with a separate composite seatback privacy shroud would not be considered a “standard” seatback and may require further investigation. Standard seatback designs containing accessories whose combined weight is less than three lbs can be accepted without further assessment for blunt trauma injury potential. These items still require assessment for the creation of sharp or injurious edges or features resulting from occupant impact.
In order to generate compliance determinations for which the objectives may be clearly met, the test methods require, by necessity, determinate pass/fail criteria. As noted in this policy, other acceptable methods of compliance which may not meet these criteria may be proposed. The inclusion of determinate pass/fail criteria is a change from the approach that was previously accepted, which allowed approval based solely on
849 comparative analysis. This change is necessary because the comparative bowling ball test could not adequately discriminate between injurious and non-injurious features. For example, a traditional seatback could have very effective energy absorption characteristics.
However, this very effective energy absorbing seatback could be modified to include an item such as an “XYZ brand” video monitor, which could result in slightly degraded energy absorption characteristics. Under these circumstances, applying the guidance provided in AC 25-17, as modified by the FAA memorandum dated July 13, 1994, would lead one to conclude that the video monitor installation was unacceptable.
The converse was also possible; an applicant could present a very rigid “standard” seatback that provided very little energy-absorbing capability. Because “standard” seatbacks have been traditionally accepted as being adequately delethalized by inspection, an applicant could then show by comparison that the addition of the same “XYZ brand” video monitor would slightly improve the energy-absorption characteristics of the seatback assembly due to the somewhat crushable nature of the video monitor screen. The applicant could then conclude that the monitor that was determined to be unacceptable in the first example would be acceptable in the second example, even though the seat in the first example would provide greater occupant injury protection. This was not the intent of the previous guidance; therefore, we have determined that changing to absolute pass/fail criteria is necessary.
Test Methods In order to determine whether or not an item is “injurious” from a blunt trauma perspective, the item should be installed in a seatback and subjected to an impact test using either a 13 pound bowling ball, a Free Motion Headform as defined in 49 CFR part 572, subpart L, or a Head Component Test Device. Schematics describing each type of test and the corresponding pass/fail criteria are contained in detail in Attachments 2 through 4. If a seatback contains more than one potentially injurious item, the test should be repeated to strike each potentially injurious item using one of the test methods described in Attachments 2 through 4. Under all three test methods potentially injurious features are struck with a test device simulating a human head traveling at a minimum velocity of 34 ft./sec. The resulting peak accelerations should not exceed 200g’s, and accelerations in excess of 80g’s should not exceed a cumulative duration of 3.0 milliseconds.
In addition to the means of compliance described in Attachments 2 through 4, it remains acceptable to utilize the other means of compliance identified above.
Considerations for Seat Technical Standard Order (TSO) Authorization Holders We believe that the vast majority of these types of component tests will be conducted on seats to address occupant injury considerations. When the seat manufacturer (TSO authorization holder) uses a seatback accessory manufacturer as a supplier, they assume