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
850 responsibility for the integration of the accessory in the seatback (Refer to AIR-100 memorandum, Policy and Guidance on the Approval of Electronic Components on Aircraft Seating Systems, dated October 27, 1998). In this case these types of tests can be conducted in parallel with the seat TSO processes but cannot be approved under the TSO authorization (or Letter of Design Approval for foreign manufacturers). If the testing is done in parallel with a TSO approval, we will accept statements made by seat TSO authorization holders regarding the pass/fail criteria pertaining to the seatback mounted accessories.
The design approval for seatback accessories is not covered by the TSO authorization.
Instead, the seat TSO design approval only covers the mass, location, and means of attachment of seatback accessories. Current industry practices show that most seat TSO holders do not wish to be held accountable for the design and manufacturing responsibility of accessories. In this case, design approval and installation approval of the accessories is the responsibility of the seat installer, even though the actual integration of the accessories into the seats is most likely accomplished by the seat manufacturer.
Whether responsibility for the approval of the seatback accessories is assumed by the TSO holder or the seat installer, it is acceptable for seat manufacturers to conduct the tests described in Attachments 2 through 4 to determine the occupant injury characteristics. In either case, adequate test article definition is still required, but can be encompassed by the seat manufacturer’s quality control system and conformity inspection processes.
A statement from the TSO authorization-holding seat manufacturer that the seatbackmounted accessories meet the pass/fail criteria described in this memorandum along with submittal of the resultant test data should be sufficient for the installer to make a determination of compliance with §§ 25.785(b) and (d). This may be a specific statement or encompassed in a more general statement, but cannot be included in the TSO applicant’s statement of conformance (per § 21.605(a)(1)), nor any other documents associated with the TSO approval (e.g., installation limitations drawing/document).
An example of the latter is as follows: The seat installer (e.g., an airplane manufacturer) includes the text from § 25.785(b) and (d) in its seat interface requirements document (or equivalent) that all seat suppliers must meet, and specifically requires that all seatback mounted accessories be evaluated for occupant injury potential (i.e., blunt trauma and sharp or injurious edges) per this memorandum. The seat supplier, upon delivery of the seats, should provide the test data and a statement to the installer that all of the requirements of the interface document have been met, thereby enabling the installer to make a determination that the occupant injury concerns have been adequately addressed.
Sharp and Injurious Edges As a result of the impact tests described above, sharp edges may be formed that are injurious or may impede egress. This is not acceptable. An assessment of sharp or
851 injurious edges must therefore be completed for each seatback mounted accessory, or any other potentially injurious item located within the headstrike zone to determine compliance with the requirements of §§ 25.785(b) and (d).
We recognize that repeated tests may be necessary to develop and refine a seat/seatback accessory configuration that meets the occupant injury requirements. As such, the costs associated with utilizing production quality accessories for repetitive impact tests can become prohibitive. In order to help reduce the costs associated with these tests, we have determined that blunt trauma evaluations and evaluations of sharp and injurious edges or features can be performed independently, if so desired. The blunt trauma tests described in Attachments 2 through 4 can be conducted utilizing surrogate test articles in accordance with FAA Policy Memorandum ANM-03-115-28, dated October 2, 2003.
Likewise, a component level assessment of sharp and injurious edges and features can be made of a seatback accessory by itself, if it is rigidly mounted in a test fixture and subjected to one of the test methods described in Attachments 2 through 4. If a seatback accessory does not show the propensity to create sharp or injurious edges when tested in a rigid fixture, this is sufficient to find compliance for the article as installed.
If testing with a surrogate test article yields unacceptable blunt trauma results, or an accessory develops sharp and injurious edges or features characteristics when tested while mounted in a rigid test fixture, it may be advantageous to more accurately represent the energy-absorbing characteristics of the seat and seatback accessory acting together as a system. In these cases it may be necessary to conduct the tests described in Attachments 2 through 4 on the accessory installed in the seatback assembly. If this testing approach still does not yield acceptable results, it remains acceptable to conduct testing to meet the HIC requirements of § 25.562(c)(5), and thereafter demonstrate that no sharp or injurious features were created.
Considerations for Airplane Manufacturers and Airplane Modifiers An airplane manufacturer/modifier may also utilize the methods described above and in Attachments 2 through 4 to determine that features located within the striking radius of an occupant’s head are non-injurious in accordance with §§ 25.785(b) and (d). In these cases, the development of an FAA-approved test plan, test article conformity, and test witnessing responsibilities must be coordinated with the aircraft certification office with oversight responsibility for the installation or modification in accordance with FAA Order 8110.4.
Effect of Policy The general policy stated in this document does not constitute a new regulation or create what the courts refer to as a “binding norm.” The office that implements policy should follow this policy when applicable to the specific project. Whenever an applicant's proposed method of compliance is outside this established policy, it must be coordinated with the policy issuing office (e.g., through the issue paper process or equivalent).
Similarly, if the implementing office becomes aware of reasons that an applicant’s
852 proposal that meets this policy should not be approved, the office must coordinate its response with the policy issuing office.
Applicants should expect that the certificating officials will consider this information when making findings of compliance relevant to new certificate actions. Also, as with all advisory material, this policy statement identifies one means, but not the only means, of compliance.
Implementation The compliance method discussed in this policy should be applied to type, amended supplemental, and amended supplemental type certification programs whose application date is on or after the date the policy is finalized. For existing certification programs whose application precedes the date this policy is effective and the methods of compliance have already been coordinated with and approved by the FAA or their designee, the applicant may continue to follow the previously acceptable methods of compliance or choose to follow the guidance contained in this policy.
/s/ Ali Bahrami Attachments Attachment 1 Attachment 2 Attachment 3 Attachment 4 Disposition of Comments
Attachment 1 Process Flowchart Are there Starr Does the aircraft NO, any potentially injurious YES, Is the combined weight of YES certification basis include features located within the 35" all seatback mounted accessories.
$ 25.562(c)(5)? headstrike arc? less than 3 Ibs?
YES NO NO Critical case blunt trauma testing must be Blunt trauma and Test for blunt accomplished in accordance with § 25.562(c)(5) sharp or injurious trauma and sharp Is the requirements. A post-test assessment for edges or features or injurious seatback a "standard" unacceptable sharp or injurious edges or features is impact testing is edges or features * NO design, i.e., able to accommodate required. For features not contacted as a result of not required to using one of the 1" permanent deformation critical case HIC testing, assess each potentially demonstrate impact tests as a result of occupant injurious item for the creation of sharp or injurious compliance with described within impact?
edges or features using one of the impact test §$ 25.785(b) (d). this policy methods described within this policy memo. memorandum.
YES Test for sharp or injurious edges or features using one of the impact tests described within this policy memorandum 853
5/18/2009 854 Attachment 2 Bowling Ball Test Device
Bowling ball tests should be conducted with a bowling ball weighing a minimum of 13.0 lbs., and instrumented with a triaxial accelerometer that records the accelerations associated with impact.
As such, this test device can be used to assess blunt trauma injuries, and investigate the propensity for components to create sharp and injurious edges. The following criteria describe the test requirements:
• Each potentially injurious seatback mounted feature within the 35” headstrike arc must be assessed. To the extent practicable, the test articles should be positioned in order for the dropped bowling ball to strike the center of each item, with a direction of motion that is perpendicular to the seatback/seatback mounted accessory. If the seat pitch is such that an item is located outside of the 35” headstrike arc, it need not be assessed.
• Each potentially injurious item should be mounted in a seat back that is connected to a rigid mounting fixture that shares the appropriate mounting points of the seat back (i.e., pivot and 18 feet
(5.5 m) Triaxial Accelerometer Bowling Ball (13 lb.)
Target
Seatback Data Acquisition
Recline Mechanism Rigid Fixture
5/18/2009 855 recline mechanism mounting). It is not necessary to represent a production seat except for the seat back, recline mechanism and their attachment to structure. As an option, it is acceptable to use a complete seat assembly, fastened to a rigid mounting fixture.
• The impact velocity must be a minimum of 34 ft./sec. Note: It is not necessary to measure the impact velocity provided the bowling ball is dropped from a minimum height of 18 feet above the impact surface.
• Electronic instrumentation shall be accomplished in accordance with SAE J211.
Accelerations shall be measured in accordance with the requirement of Channel Class 1000.
• Pass / Fail Criteria: Peak accelerations shall not exceed 200g’s; accelerations in excess of 80g’s shall not exceed a cumulative duration of 3.0 milliseconds. The impact shall not cause the formation of any sharp or injurious edges or features that may impede egress.
5/18/2009 856 Attachment 3 Head Component Tester
The head component test device is a Hybrid II Anthropomorphic Test Dummy (ATD) head and neck mounted on a pendulum. The head/neck assembly is accelerated with a pneumatic piston to achieve the desired impact velocity. The ATD head is instrumented with an accelerometer that records the acceleration forces associated with the impact. As such, this test device can be used to assess blunt trauma injuries, and evaluate the propensity for components to create sharp and injurious edges. The following criteria describe the test requirements:
• Each potentially injurious seatback mounted feature within the 35” headstrike arc must be assessed. To the extent practicable, the test articles should be positioned in order to be struck in the center by the headformstrike the center of each item, with a direction of motion that is perpendicular to the seatback/seatback mounted accessory. If the seat pitch is such that an item is located outside of the 35” headstrike arc, it need not be assessed.
Nitrogen Bottle Triaxial Accelerometer - Hybrid II ATD Headform & Neck
Target Rigid Fixture Recline Mechanism Fire Control & Data Acquisition Pressure Accumulator Vessel Piston High Pressure Supply Line Control Signal Data Lead
5/18/2009 857
• Each potentially injurious item should be mounted in a seat back that is connected to a rigid mounting fixture that shares the appropriate mounting points of the seat back (i.e., pivot and recline mechanism mounting). It is not necessary to represent a production seat except for the seat back, recline mechanism and their attachment to structure. As an option, it is acceptable to use a complete seat assembly, fastened to a rigid mounting fixture.
• The ATD forehead should be the initial point of contact, and should strike the center of the target.
• The impact velocity must be a minimum of 34 ft./sec.
• Electronic instrumentation shall be accomplished in accordance with SAE J211.
Accelerations shall be measured in accordance with the requirement of Channel Class 1000.
• Pass / Fail Criteria: Peak accelerations shall not exceed 200g’s; accelerations in excess of 80g’s shall not exceed a cumulative duration of 3.0 milliseconds. The impact shall not cause the formation of any sharp or injurious edges or features that may impede egress.
5/18/2009 858 Attachment 4 Free Motion Headform Test Device
The Free Motion Headform (FMH) device is defined in 49 CFR part 572, subpart L, and is used primarily by the automotive industry to demonstrate compliance to Federal Motor Vehicle Safety Standards (FMVSS) 201U. This device can be used in a manner similar to FMVSS 201 to evaluate blunt trauma injury, and to assess the propensity for components to create sharp and injurious edges. The following criteria describe the test requirements:
• Each potentially injurious seatback mounted feature within the 35” headstrike arc must be assessed. To the extent practicable, the test articles should be positioned in order to be struck in strike the center by the headformof each, with a direction of motion that is perpendicular to the seatback/seatback mounted accessory. If the seat pitch is such that an item is located outside of the 35” headstrike arc, it need not be assessed.
• Each potentially injurious item should be mounted in a seat back that is connected to a rigid mounting fixture that shares the appropriate mounting points of the seat back (i.e., pivot and recline mechanism mounting). It is not necessary to represent a production seat except for the seat back, recline mechanism and their attachment to structure. As an option, it is acceptable to use a complete seat assembly, fastened to a rigid mounting fixture.
Fire Control & Data Acquisition Pressure Accumulator Vessel Piston Nitrogen Bottle Headform Target Rigid Fixture Recline Mechanism Control Signal Data Lead High Pressure Supply Line
5/18/2009 859
• The FMH forehead should be the initial point of contact, and should strike the center of the target.
• The impact velocity shall be at least 34 ft./sec.
• Electronic instrumentation shall be accomplished in accordance with SAE J211.
Accelerations shall be measured in accordance with the requirement of Channel Class 1000.
• Pass / Fail Criteria: Peak accelerations shall not exceed 200g’s; accelerations in excess of 80g’s shall not exceed a cumulative duration of 3.0 milliseconds. The impact shall not cause the formation of any sharp or injurious edges or features that may impede egress.
5/18/2009 860
DISPOSITION OF PUBLIC
COMMENTS ON DRAFT
POLICY STATEMENT ANM-03-115-31,
CONDUCTING
COMPONENT LEVEL
TESTS TO
DEMONSTRATE
COMPLIANCE WITH
25.785(B) AND (D)
Commenter Comment Disposition Transport Canada (TCAA) TCAA is fully supportive of this FAA action to formally adopt these aspects of the harmonized guidance material developed in the ARAC SHWG.
Concur – no change required.
TCAA The FAA is encouraged to process the formal adoption of the remaining material from the group’s Task 3 product.
Concur - The FAA plans to continue to address the remaining issues associated with the Task 3 project.
TCAA The policy memorandum excludes the continued use of the comparative bowling ball test for demonstrating compliance with § 25.785(b),(d). The rationale for this position is detailed in the policy memorandum and is supported by TCAA Concur – no change required.
TCAA The use of surrogate test articles in lieu of production quality accessories for blunt trauma tests was not considered in the ARAC discussions. TCAA supports the use of compliance methods, which minimize the burden on applicants, while ensuring that the applicable standards are properly addressed.
Concur – no change required.
TCAA In the section under “Sharp and Injurious Edges,” TCAA suggests that the words be Concur –the words have been revised according to the TCAA recommendation.