1、SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefro
2、m, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions.Copyright 2001 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.S.
3、A.TO PLACE A DOCUMENT ORDER: (724) 776-4970 FAX: (724) 776-0790 SAE WEB ADDRESS: http:/www.sae.org400 Commonwealth Drive, Warrendale, PA 15096-0001AEROSPACE RECOMMENDED PRACTICEARP5497Issued 2001-10Modification or Replacement ofComponents on Dynamically Certified Seat SystemsFOREWORDSeat designs mus
4、t be approved by the appropriate regulatory agency. The Federal Aviation Administration (FAA) approval process can take the form of a Technical Standard Order (TSO) authorization, and/or be part of a type certification approval (either in the original type certificate, a supplemental type certificat
5、e, or by amendment to the type certificate), or be under a Parts Manufacturer Approval (PMA). TSO authorization is currently based on qualification of the seat in accordance with the requirements of AS8049. Modification of an approved design creates a new configuration that must also be approved by
6、the FAA.In accordance with Title 14 of the Code of Federal Regulations (14 CFR), Part 21, Section 21.611, the manufacturer of an article under TSO authorization may make minor design changes without further FAA approval. TSO article design changes, whether major or minor, by a person other than the
7、original manufacturer, are handled pursuant to 14 CFR, Section 21.611(c), and the modifier must apply for a separate authorization and must develop the article in accordance with DOT-FAA Document No. 8150.1A. If approval is sought under 14 CFR, Part 43 (specifically Appendix A(a)(4), or under applic
8、able airworthiness regulations, the design change is considered a major alteration. If the design change is being made to an article that has been in service or may have deteriorated while in storage, it must be shown that the altered article meets the original TSO requirements.Design changes and th
9、eir evaluation need to consider both the requirements for that specific article, such as the requirements outlined in a TSO, and the requirements for the installation of that article, which are specific to the aircraft and its interior arrangement. Approval in either case is necessary prior to the i
10、nstallation of the modified item on the aircraft. This may require that both the Installer and the Manufacturer obtain approval from the FAA.SAE ARP5497 - 2 -1. SCOPE:This document outlines the engineering evaluation appropriate for modifying or replacing components of a previously certified seat wh
11、en the certification process is based on qualification to the requirements of AS8049, which includes dynamic testing. The engineering evaluation presented in this document may be used to determine if a modification (including replacement of a component) is a minor change with respect to meeting the
12、dynamic testing requirements described in AS8049. Whenever a modification is considered, the ability to meet all requirements of the applicable Federal Aviation Regulation (FAR) must be verified. For example, this would include the capability to meet requirements such as flammability and flotation.
13、Analysis and/or test data supporting the ability of the new materials and/or configuration to meet the applicable requirements must be submitted with the change documentation.This document addresses the evaluation of seat pan cushions, secondary components, and ancillary components. Other primary co
14、mponents such as restraint systems and primary structural components are not considered.2. REFERENCES:2.1 Applicable Documents:The following publications form a part of this document to the extent specified herein. The latest issue of SAE publications shall apply. The applicable issue of other publi
15、cations shall be the issue in effect on the date of the purchase order. In the event of conflict between the text of this document and references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific
16、exemption has been obtained.2.1.1 SAE Publications: Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.AS8049A Performance Standard for Seats in Civil Rotorcraft, Transport Aircraft, and General Aviation AircraftSAE ARP5497 - 3 -2.1.2 U.S. Government Publications: Available from D
17、ODSSP, Subscription Services Desk, Building 4D, 700 Robbins Avenue, Philadelphia, PA 19111-5094.14CFR 21.605 Application and Issue14CFR 21.611 Design Changes14CFR 21.93 Classification of Changes in Type Design14CFR 23.562 Emergency Landing Dynamic Conditions14CFR 25.562 Emergency Landing Dynamic Con
18、ditions14CFR 27.562 Emergency Landing Dynamic Conditions14CFR 29.562 Emergency Landing Dynamic ConditionsDOT-FAA Order 8150.1A Technical Standard Order ProceduresFAA Advisory Circular No. 20-137 Dynamic Evaluation of Seat Restraint Systems and Occupant Restraint for Rotorcraft (Normal and Transport)
19、FAA Advisory Circular No. 21-25A Approval of Modified Seating Systems Initially Approved Under a Technical Standard OrderFAA Advisory Circular No. 23.562-1 Dynamic Testing of Part 23 Airplane Seat/Restraint Systems and Occupant ProtectionFAA Advisory Circular No. 25-17 Transport Airplane Cabin Inter
20、iors Crashworthiness HandbookFAA Advisory Circular No. 25.562-1 Dynamic Evaluation of Seat Restraint Systems and Occupant Protection on Transport AirplanesTSO-C127a Rotorcraft, Transport Airplane, and Normal and Utility Airplane Seating Systems2.2 Definitions:PRIMARY COMPONENT: Components that, if m
21、odified, could change the results of dynamic testing. Primary components include, but are not limited to, all components in the structural load path of the seat and those components that affect the spinal compression load, Head Injury Criterion (HIC) value(s), upper-torso restraint load, and femur c
22、ompression load (when necessary) measured during dynamic testing. Examples of primary components include restraint system and its attachments, seat legs and other major structural members of the seat frame, fittings that interface with the aircraft, seat pan cushion cores, and items in the head stri
23、ke area of the occupant of that seat or nearby seats.SECONDARY COMPONENT: Components that, if modified, would not be expected to change the results of dynamic testing. Secondary components do not contribute to reacting the inertial loads generated during the test nor do they influence HIC values, up
24、per-torso restraint load, or the spinal and femur (when appropriate) compression loads. Secondary components must be retained during the dynamic tests. Examples of items that could be secondary components include In-flight Entertainment (IFE) units, life jackets, fabric/leather upholstery or seat co
25、vers, seat back cushion cores, passenger control units, and power boxes. SAE ARP5497 - 4 -2.2 (Continued):In some cases the application or position of the component is critical to the determination of whether it is a primary or secondary component. A corded device placed in an armrest would likely b
26、e a secondary component, because while it must be retained on the seat during testing, it would not be supporting any inertial loads and is not in a position to influence the HIC values measured. However, a corded device in a seat back in front of an occupant would be a primary component if it is li
27、kely to be impacted and influence the HIC value measured in the dynamic test.ANCILLARY COMPONENT: In order for an item to be considered an ancillary component, the mass of the item is so small that it is inconsequential to the dynamic test results. Detachment of these items during dynamic testing wo
28、uld not invalidate dynamic test results. Examples of ancillary equipment include in-arm ashtrays and pieces of decorative trim. It should also be noted that although detachment of a piece of ancillary equipment is not cause for failure or retest, the method of retaining the item should be improved s
29、o that the seat will retain the item under dynamic test conditions.MAJOR CHANGE: A major change is defined by 14 CFR, 21.611(b) as “Any design change by the manufacturer that is extensive enough to require a substantially complete investigation to determine compliance with a TSO .”MINOR CHANGE: A mi
30、nor change is defined in 14 CFR, 21.93(a) as a change ” . . . that has no appreciable effect on the weight, balance, structural strength, reliability, operational characteristics, or other characteristics affecting the airworthiness of the product.” A minor change results in an item that is essentia
31、lly the same as that which was dynamically tested. There may be a part number change in order to maintain configuration control, but the model number would not change. The performance of the system is supported by the original dynamic tests, although some additional analysis and/or testing may be ne
32、cessary to verify that the change maintains the same level of performance as was demonstrated in the original dynamic tests.BALLAST WEIGHT: Weight of mass added to the seat during the original seat certification dynamic test program.SEAT ASSEMBLY WEIGHT: The seat assembly weight, based on the testin
33、g conducted, is the weight of the seat tested including any ballast that accounts for variations in production seat weight and future growth in the weight of the seat. The seat assembly weight does not include the weights of the anthropomorphic test dummies or the ballast added to the seat to repres
34、ent specific items that may be attached to or retained by the seat such as magazines, life preservers, luggage, and other items.SAE ARP5497 - 5 -2.2 (Continued):ULTIMATE MARGIN OF SAFETY (M.S.ult): The ultimate margin of safety is defined by Equation 1:(Eq. 1)3. PRIMARY COMPONENT EVALUATION:Because
35、primary components determine the results of dynamic testing, the replacement or modification of primary components requires a detailed evaluation of how the test results could be altered.3.1 Performance Factors for Seat Pan Cushions:The following performance factors, and how test results could chang
36、e, should be considered in evaluating seat pan cushion replacement:a. Lumbar Load. The cushion load versus deflection characteristics under dynamic loading are critical in determining the lumbar loads resulting from dynamic testing.b. Submarining. The load deflection characteristics and the general
37、occupant support provided by the seat pan cushion can influence the pelvis motion during dynamic testing and thus influence whether or not submarining of the occupant under the lap belt occurs during the dynamic tests.c. Restraint Loads. The changes in the cushion deflection affect the occupant moti
38、on and thus also affect the loads developed in the restraint system and the restraint system position during the dynamic testing.d. Head Motion. Changes in pelvic motion will also change the torso motion and the resulting head motion.e. Initial Position of the Occupant. The initial position of the o
39、ccupant influences the overall performance of the seat (through occupant Center of Gravity (CG) position) and the resulting occupant motion during the dynamic test changing occupant head path and restraint reaction loads.M.S.ultAllowable Ultimate LoadRequired Ultimate Load- 1=SAE ARP5497 - 6 -3.2 Gu
40、idelines for Substantiating a Seat Pan Cushion Replacement:The following guidelines should be used for designing an alternate seat pan cushion intended to perform similarly to the originally qualified design and which, with proper material evaluation and testing, could be substantiated as equivalent
41、 to the original cushion used in dynamic testing.a. The occupant must be supported at the same position1under a 1-G loading. This includes the position of the SRP/BRP, the seat back tangent angle, and the thigh support angle.b. The characteristics of the seat pan cushion affect the motion and loadin
42、g of the occupant in both vertical and horizontal dynamic tests. Therefore, these characteristics, under dynamic loading conditions, must be similar to the qualified cushion. The degree of similarity required would depend on the particular application and the following areas should be considered:1.
43、The load-versus-deflection characteristics of the seat pan cushion under both static and dynamic loading conditions. Any absorption of energy and/or rate sensitivity characteristics of the cushion must be considered because these characteristics affect the timing and maximum value of the loads devel
44、oped between the occupant and the seat.2. The load-to-seat pan application location. This must be similar to the qualified cushion so that the seat will react to the required loading in a manner similar to that during previously conducted tests.c. Specifically, it must be shown by test or analysis t
45、hat the peak lumbar load that would be measured during dynamic testing would be less than 1500 lb.d. The load-versus-deflection characteristics of the seat pan cushion should also be evaluated to ensure that they do not adversely affect the potential for submarining, the restraint system loads measu
46、red during testing, or the head motion measured during testing.e. The items listed in Section 4 for Secondary Component Evaluation must also be evaluated to ensure the cushion does not adversely affect the dynamic performance of the seat.4. SECONDARY COMPONENT EVALUATION:Secondary components must be
47、 evaluated to show that the test results would not be adversely altered by the modification and that the component will still be retained on the seat.If evaluation of the following issues shows that the dynamic test results would not be adversely altered by the modification, the change can typically
48、 be considered a minor change. The flowchart in Figure 1 can be used to support this evaluation.1. Industry guidance or regulatory requirements should be used in determining any tolerance associated with the position of the SRP on the cushion. A draft ARAC document offers the following guidance: “Co
49、ntour variations are acceptable without additional 16G and 14G structural tests provided the SRP does not vary by more than 0.75 inch in any direction from the SRP of the tested seat.“SAE ARP5497 - 7 -FIGURE 1 - Flow Chart for Evaluating Modifications to Secondary ComponentsSAE ARP5497 - 8 -FIGURE 1 - Flow Chart for Evaluating Modifications to Secondary Components (Continued)SAE ARP5497 - 9 -FIGURE 1 - Flow Chart for Evaluating Modifications to Secondary Components (Continued)SAE ARP5497 -
