[Federal Register Volume 89, Number 50 (Wednesday, March 13, 2024)]
[Rules and Regulations]
[Pages 18341-18348]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-05226]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2023-2435; Special Conditions No. 25-862-SC]


Special Conditions: Gulfstream Aerospace Corporation Model GVIII-
G700 and GVIII-G800 Series Airplanes; Dynamic Test Requirements for 
Single- and Multiple-Occupant Side-Facing Seats With or Without Airbag 
Systems

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the Gulfstream 
Aerospace Corporation (Gulfstream) Model GVIII-G700 and GVIII-G800 
series airplanes. These airplanes will have a novel or unusual design 
feature when compared to the state of technology envisioned in the 
airworthiness standards for transport category airplanes. This design 
feature is side-facing seats oriented in the aircraft with the occupant 
facing 90 degrees to the direction of aircraft travel. The applicable 
airworthiness regulations do not contain adequate or appropriate safety 
standards for this design feature. These special conditions contain the 
additional safety standards that the Administrator considers necessary 
to establish a level of safety equivalent to that established by the 
existing airworthiness standards.

DATES: Effective March 13, 2024.

FOR FURTHER INFORMATION CONTACT: Myra Kuck, Cabin Safety, AIR-624, 
Technical Policy Branch, Policy and Standards Division, Aircraft 
Certification Service, Federal Aviation Administration, Aircraft 
Certification Policy and Standards, 3960 Paramount Blvd., Suite 100, 
Lakewood, CA 90712; telephone and fax 405-666-1059; email 
[email protected].

SUPPLEMENTARY INFORMATION:

Background

    On December 31, 2019, Gulfstream applied for an amendment to Type 
Certificate No. T00015AT to include the new Model GVIII-G700 and GVIII-
G800 series airplanes. These airplanes, which will be derivatives of 
the Model GVI currently approved under Type Certificate No. T00015AT, 
are twin-engine, transport-category airplanes, with seating for 19 
passengers, and a maximum take-off weight of 107,600 pounds (GVIII-
G700) and 105,600 pounds (GVIII-G800).

Type Certification Basis

    Under the provisions of title 14, Code of Federal Regulations (14 
CFR) 21.101, Gulfstream must show that the Model GVIII-G700 and GVIII-
G800 series airplanes meet the applicable provisions of the regulations 
listed in Type Certificate No. T00015AT, or the applicable regulations 
in effect on the date of application for the change, except for earlier 
amendments as agreed upon by the FAA.

[[Page 18342]]

    If the Administrator finds that the applicable airworthiness 
regulations do not contain adequate or appropriate safety standards for 
the Gulfstream Model GVIII-G700 and GVIII-G800 series airplanes because 
of a novel or unusual design feature, special conditions are prescribed 
under the provisions of Sec.  21.16.
    Special conditions are initially applicable to the model for which 
they are issued. Should the type certificate for that model be amended 
later to include any other model that incorporates the same novel or 
unusual design feature, or should any other model already included on 
the same type certificate be modified to incorporate the same novel or 
unusual design feature, these special conditions would also apply to 
the other model under Sec.  21.101.
    In addition to the applicable airworthiness regulations and special 
conditions, the Gulfstream Model GVIII-G700 and GVIII-G800 series 
airplanes must comply with the exhaust-emission requirements of 14 CFR 
part 34, and the noise-certification requirements of 14 CFR part 36.
    The FAA issues special conditions, as defined in 14 CFR 11.19, in 
accordance with 14 CFR 11.38, and they become part of the type 
certification basis under Sec.  21.101.

Novel or Unusual Design Feature

    The Gulfstream Model GVIII-G700 and GVIII-G800 airplanes will 
incorporate the following novel or unusual design feature:
    Side-facing seats, oriented in the aircraft with the occupant 
facing 90 degrees to the direction of aircraft travel, with or without 
incorporation of an airbag systems or inflatables.

Discussion

    On June 16, 1988, 14 CFR part 25 was amended to revise the 
emergency landing conditions that must be considered in the design of 
transport category airplanes. This amendment (25-64) revised the static 
load conditions in Sec.  25.561 and added a new Sec.  25.562 that 
required dynamic testing for all seats approved for occupancy during 
takeoff and landing. The intent of Amendment 25-64 was to provide an 
improved level of safety for occupants on transport category airplanes; 
however, because most seating on transport category airplanes is 
forward-facing, the pass/fail criteria developed in Amendment 25-64 
focused primarily on these seats.
    Prior to 2012, the FAA granted exemptions \1\ for the multiple-
place side-facing-seat installations because the existing test methods 
and acceptance criteria did not produce a level of safety equivalent to 
the level of safety provided for forward-and aft-facing seats. These 
exemptions were subject to many conditions that reflected the injury-
evaluation criteria and mitigation strategies available at the time of 
the exemption issuance. The FAA also issued special conditions to 
address single-place side-facing seats because it determined, at the 
time, that those conditions provided the same level of safety as for 
forward- and aft-facing seats.
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    \1\ See, generally, Exemption Nos. 7120C, 7878A, and 9900.
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    Due to the novelty of side-facing seats in transport category 
airplanes, acceptable safety measures for Sec.  25.562 were unknown. 
The FAA conducted research to develop an acceptable method of 
compliance with Sec. Sec.  25.562 and 25.785(b) for side-facing seat 
installations. That research has identified injury considerations and 
evaluation criteria in addition to those previously used to approve 
side-facing seats (see published report DOT/FAA/AR-09/41, July 2011 
\2\). One particular concern that was identified during the FAA's 
research program but not addressed in special conditions prior to 2012 
was the significant leg injuries that can occur to occupants of both 
single- and multiple-place side-facing seats. Because this type of 
injury does not occur on forward- and aft-facing seats, the FAA 
determined that to achieve the level of safety envisioned in Amendment 
25-64, additional requirements would be needed as compared to 
previously issued special conditions. Nonetheless, the research has now 
allowed the development of a single set of special conditions that is 
applicable to all fully side-facing seats.
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    \2\ Document available at https://www.tc.faa.gov/its/worldpac/techrpt/ar09-41.pdf.
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    On November 5, 2012, the FAA released PS-ANM-25-03-R1, ``Technical 
Criteria for Approving Side-Facing Seats,'' to update existing FAA 
certification policy on Sec. Sec.  25.562 and 25.785(a) and (b) at 
Amendment 25-64 for single- and multiple-place side-facing seats. This 
policy addressed both the technical criteria for approving side-facing 
seats and the implementation of those criteria. The FAA methodology 
detailed in PS-ANM-25-03-R1 has been used to develop these special 
conditions. Some of the conditions issued for previous exemptions are 
still relevant and are included in these special conditions; however, 
others have been replaced by different criteria that reflect current 
research findings described above, as well as design features from the 
Gulfstream GVII model side-facing seat design.
    The special conditions contain the additional safety standards that 
the Administrator considers necessary to establish a level of safety 
equivalent to that established by the existing airworthiness standards.

Discussion of Comments

    The FAA issued Notice of Proposed Special Conditions No. 25-23-07-
SC for the Gulfstream Model GVIII-G700 and GVIII-G800 airplanes, which 
was published in the Federal Register on February 1, 2024 (89 FR 6443).
    The FAA received responses from two anonymous commenters. One 
commenter stated that they support the special conditions as proposed. 
The second commenter requested the FAA make the following changes to 
the proposed special conditions:
    1. The commenter requested the FAA replace the term ``airbag'' with 
``automatically deploying safety system.'' The commenter stated that it 
should be clear that the installation of a different kind of 
automatically deploying safety system would necessitate the issuance of 
a new special condition. The FAA acknowledges that the current 
automatically-deploying safety systems proposed by applicants are 
airbag systems. If in the future the technology proposed by applicants 
should change, then there may be need for another special condition. No 
changes were made to these special conditions as a result of this 
comment.
    2. The commenter stated that the proposed special conditions 
paragraph 1.e(1)(b) may cause confusion, in that the word ``bottom'' is 
singular and the word ``feet'' is plural. This wording, according to 
the commenter, could lead to an interpretation that the force of about 
20 pounds (lbs) may be applied to each foot, plus it is not specified 
that the force be applied uniformly. The commenter also suggested a 
specific revision to the text of this paragraph to address these 
concerns. The FAA disagrees that there is ambiguity or that a change is 
necessary. The 20 lbs of force is the total force applied to the bottom 
of the feet. The text of the special condition is similar to the 
language of FAA Policy Statement PS-ANM-25-03-R1 ``Technical Criteria 
for Approving Side-Facing Seats.'' No changes were made to these 
special conditions as a result of this comment.
    3. The commenter suggested several changes to the formatting and 
technical

[[Page 18343]]

content of paragraph 2.g. of the special conditions. The commenter 
suggested adding a colon at the end of paragraph g., and that 
subsequent special conditions should be numbered below that paragraph. 
The commenter also stated that paragraph 2.g. does not explicitly state 
when lap belt tension must be limited to 250 lbs, and that the 
rationale for the limit in the Civil Aerospace Medical Institute (CAMI) 
report does not have to be specified in the proposed special 
conditions. The commenter further stated that paragraph 2.g. has a 
typographical error in that data should be filtered at ``CFC 600'' as 
defined in SAE JS211-1 ``Surface Vehicle Recommended Practice.'' The 
FAA agrees with most of the comments received on paragraph 2.g. The FAA 
has revised the formatting of paragraph 2.g. to reflect the 
requirements clearly. The FAA does not concur with the commenter that 
the data should be filtered at CFC 600 versus 60. Sixty is the correct 
value for belt loads in SAE JS211-1.
    4. The commenter made two comments regarding paragraph 4.a. of 
these special conditions. The commenter suggested the FAA revise the 
phrase ``that range of occupants'' because it is missing explanation as 
to which range of occupants is being referred to. The FAA disagrees. 
The range of occupants is provided in Paragraph 3.b. Paragraph 3. 
states that ``For all airbag systems in the shoulder harness and for 
leg flail the following apply'' . . . Paragraph b. states that the 
means of protection must take into consideration a range of stature 
from a 2-year-old child to a 95th percentile male.
    The commenter further stated that in paragraph 4.a., the situations 
that must be considered do not account for the possibility that the 
seat occupant is a child in a child restraint device or booster seat. 
The FAA disagrees. Booster seats are not allowed. If a child restraint 
device is installed, the installation must show it would not harm the 
occupant, otherwise an operating limitation would need to limit to no 
child restraint device per condition 4.b. No changes were made to these 
special conditions as a result of this comment.
    Except as discussed above, the special conditions are adopted as 
proposed.

Applicability

    As discussed above, these special conditions are applicable to the 
Gulfstream Model GVIII-G700 and GVIII-G800 series airplanes. Should 
Gulfstream apply at a later date for a change to the type certificate 
to include another model that incorporates the same novel or unusual 
design feature, or should any other model already included on the same 
type certificate be modified to incorporate the same novel or unusual 
design feature, these special conditions would apply to the other model 
as well.
    Under standard practice, the effective date of final special 
conditions would be 30 days after the date of publication in the 
Federal Register. However, as the certification date for the Gulfstream 
Model GVIII-G700 and GVIII-G800 series airplanes is imminent, the FAA 
finds that good cause exists to make these special conditions effective 
upon publication.

Conclusion

    This action affects only a certain novel or unusual design feature 
on Gulfstream Model GVIII-G700 and GVIII-G800 series of airplanes. It 
is not a rule of general applicability.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

Authority Citation

    The authority citation for these special conditions is as follows:

    Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701, 44702, 44704.

The Special Conditions

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special conditions are issued as part of 
the type certification basis for Gulfstream Model GVIII-G700 and GVIII-
G800 series airplanes.
    In addition to the airworthiness standards in Sec. Sec.  25.562 and 
25.785, the FAA issues the following special conditions as part of the 
type certification basis for the Gulfstream Model GVIII-G700 and GVIII-
G800 series aircraft. Items 1 through 3 are applicable to all side-
facing seat installations on these airplanes. Item 4 imposes additional 
requirements applicable to side-facing seats equipped with an airbag 
system in the shoulder belt. Item 5 imposes additional requirements 
applicable to side-facing seats equipped with leg-flail airbag systems.
    1. Additional requirements applicable to tests or rational analysis 
conducted to show compliance with Sec. Sec.  25.562 and 25.785 for 
side-facing seats:
    a. The longitudinal test(s) conducted in accordance with Sec.  
25.562(b)(2) to show compliance with the seat-strength requirements of 
Sec.  25.562(c)(7) and (8), and these special conditions must have an 
ES-2re anthropomorphic test dummy (ATD) (49 CFR part 572 subpart U) or 
equivalent, or a Hybrid-II ATD (49 CFR part 572, subpart B as specified 
in Sec.  25.562) or equivalent, occupying each seat position and 
including all items contactable by the occupant (e.g., armrest, 
interior wall, or furnishing) if those items are necessary to restrain 
the occupant. If included, the floor representation and contactable 
items must be located such that their relative position, with respect 
to the center of the nearest seat place, is the same at the start of 
the test as before floor misalignment is applied. For example, if floor 
misalignment rotates the centerline of the seat place nearest the 
contactable item 8 degrees clockwise about the aircraft x-axis, then 
the item and floor representations must be rotated by 8 degrees 
clockwise also to maintain the same relative position to the seat 
place, as shown in Figure 1. Each ATD's relative position to the seat 
after application of floor misalignment must be the same as before 
misalignment is applied. The ATD pelvis must remain supported by the 
seat pan, and the restraint system must remain on the pelvis and 
shoulder of the ATD until rebound begins. No injury-criteria evaluation 
is necessary for tests conducted only to assess seat-strength 
requirements.
    b. The longitudinal test(s) conducted in accordance with Sec.  
25.562(b)(2), to show compliance with the injury assessments required 
by Sec.  25.562(c) and these special conditions, may be conducted 
separately from the test(s) to show structural integrity. Structural-
assessment tests must be conducted as specified in paragraph 1.a., 
above, and the injury-assessment test must be conducted without yaw or 
floor misalignment. Injury assessments may be accomplished by testing 
with ES-2re ATD (49 CFR part 572 subpart U) or equivalent at all 
places. Alternatively, these assessments may be accomplished by 
multiple tests that use an ES-2re at the seat place being evaluated, 
and a Hybrid-II ATD (49 CFR part 572, subpart B, as specified in Sec.  
25.562) or equivalent used in all seat places forward of the one being 
assessed, to evaluate occupant interaction. Seat places aft of the one 
being assessed may be unoccupied. If a seat installation includes 
adjacent items that are contactable by the occupant, the injury 
potential of that contact must be assessed. To make this assessment, 
tests may be conducted that include the actual item, located, and 
attached in a representative fashion. Alternatively, the injury 
potential may be assessed by a combination of tests with items having

[[Page 18344]]

the same geometry as the actual item, but having stiffness 
characteristics that would create the worst case for injury (injuries 
due to both contact with the item and lack of support from the item).
    c. If a seat is installed aft of structure (e.g., an interior wall 
or furnishing) that does not have a homogeneous surface contactable by 
the occupant, additional analysis and/or test(s) may be required to 
demonstrate that the injury criteria are met for the area which an 
occupant could contact. For example, different yaw angles could result 
in different injury considerations and may require additional analysis 
or separate test(s) to evaluate.
    d. To accommodate a range of occupant heights (5th percentile 
female to 95th percentile male), the surface of items contactable by 
the occupant must be homogenous 7.3 inches (185 mm) above and 7.9 
inches (200 mm) below the point (center of area) that is contacted by 
the 50th percentile male size ATD's head during the longitudinal 
test(s) conducted in accordance with paragraphs a, b, and c, above. 
Otherwise, additional head-injury criteria (HIC) assessment tests may 
be necessary. Any surface (inflatable or otherwise) that provides 
support for the occupant of any seat place must provide that support in 
a consistent manner regardless of occupant stature. For example, if an 
inflatable shoulder belt is used to mitigate injury risk, then it must 
be demonstrated by inspection to bear against the range of occupants in 
a similar manner before and after inflation. Likewise, the means of 
limiting lower-leg flail must be demonstrated by inspection to provide 
protection for the range of occupants in a similar manner.
    e. For longitudinal test(s) conducted in accordance with Sec.  
25.562(b)(2) and these special conditions, the ATDs must be positioned, 
clothed, and have lateral instrumentation configured as follows:
    (1) ATD positioning:
    Lower the ATD vertically into the seat while simultaneously (see 
Figure 2 for illustration):
    (a) Aligning the midsagittal plane (a vertical plane through the 
midline of the body; dividing the body into right and left halves) with 
approximately the middle of the seat place.
    (b) Applying a horizontal x-axis direction (in the ATD coordinate 
system) force of about 20 pounds (lbs) (89 Newtons [N]) to the bottom 
of the feet of the ATD with the legs straight, to compress the seat 
back cushion.
    (c) Keeping the legs nearly horizontal by supporting them just 
behind the ankles.
    (d) Once all lifting devices have been removed from the ATD:
    (i) Rock it slightly to settle it in the seat.
    (ii) Gently lower the ankles of the ATD bending the legs at the 
knee joints. Do not allow the pelvis of the ATD to be moved when the 
lower legs are lowered. The seat back cushion must remain compressed. 
Separate the knees by about 4 inches (100 mm).
    (iii) Set the ES-2re's head at approximately the midpoint of the 
available range of z-axis rotation (to align the head and torso 
midsagittal planes).
    (iv) Position the ES-2re's arms at the joint's mechanical detent 
that puts them at approximately a 40-degree angle with respect to the 
torso. Position the Hybrid-II ATD hands on top of its upper legs.
    (v) Position the feet such that the centerlines of the lower legs 
are approximately parallel to a lateral vertical plane (in the aircraft 
coordinate system).
    (2) ATD clothing: Clothe each ATD in form-fitting, mid-calf-length 
(minimum) pants and shoes (size 11E) weighing about 2.5 lb (1.1 Kg) 
total. The color of the clothing should be in contrast to the color of 
the restraint system. The ES-2re jacket is sufficient for torso 
clothing, although a form-fitting shirt may be used in addition if 
desired.
    (3) ES-2re ATD lateral instrumentation: The rib-module linear 
slides are directional, i.e., deflection occurs in either a positive or 
negative ATD y-axis direction. The modules must be installed such that 
the moving end of the rib module is toward the front of the aircraft. 
The three abdominal-force sensors must be installed such that they are 
on the side of the ATD toward the front of the aircraft.
    f. The combined horizontal/vertical test, required by Sec.  
25.562(b)(1) and these special conditions, must be conducted with a 
Hybrid II ATD (49 CFR part 572 subpart B as specified in Sec.  25.562), 
or equivalent, occupying each seat position.
    g. Restraint systems:
    (1) If inflatable restraint systems are used, they must be active 
during all dynamic tests conducted to show compliance with Sec.  
25.562.
    (2) The design and installation of seat-belt buckles must prevent 
unbuckling due to applied inertial forces or impact of the hands/arms 
of the occupant during an emergency landing.
    2. Additional performance measures applicable to tests and rational 
analysis conducted to show compliance with Sec. Sec.  25.562 and 25.785 
for side-facing seats:
    a. Body-to-body contact: Contact between the head, pelvis, torso, 
or shoulder area of one ATD with the adjacent-seated ATD's head, 
pelvis, torso, or shoulder area is not allowed. Contact during rebound 
is allowed.
    b. Thoracic: The deflection of any of the ES-2re ATD upper, middle, 
and lower ribs must not exceed 1.73 inches (44 mm). Data must be 
processed as defined in Federal Motor Vehicle Safety Standards (FMVSS) 
571.214.
    c. Abdominal: The sum of the measured ES-2re ATD front, middle, and 
rear abdominal forces must not exceed 562 lbs (2,500 N). Data must be 
processed as defined in FMVSS 571.214.
    d. Pelvic: The pubic symphysis force measured by the ES-2re ATD 
must not exceed 1,350 lbs (6,000 N). Data must be processed as defined 
in FMVSS 571.214.
    e. Leg: Axial rotation of the upper-leg (femur) must be limited to 
35 degrees in either direction from the nominal seated position.
    f. Neck: As measured by the ES-2re ATD and filtered at CFC 600 as 
defined in SAE J211:
    (1) The upper-neck tension force at the occipital condyle (O.C.) 
location must be less than 405 lb (1,800 N).
    (2) The upper-neck compression force at the O.C. location must be 
less than 405 lb (1,800 N).
    (3) The upper-neck bending torque about the ATD x-axis at the O.C. 
location must be less than 1,018 in-lb (115 Nm).
    (4) The upper-neck resultant shear force at the O.C. location must 
be less than 186 lb (825 N).
    g. Occupant (ES-2re ATD) retention: The upper-torso restraint 
straps (if present) must remain on the ATD's shoulder during the 
impact. The pelvic restraint must remain on the ES-2re ATD's pelvis 
during the impact. The pelvic restraint must remain on the ES-2re ATD's 
pelvis during rebound unless the following criteria are met.
    (1) A measurement of the belt loop load during the time when the 
belt moves above the pelvis (submarining) must not exceed 500 lbs 
(2,225 N) (a 250 lb (1112.5 N) lap belt tension limit). Data must be 
filtered at CFC 60 as defined in SAE J211. To evaluate the pelvic 
restraint performance using this criterion, three things are needed:
    (a) A clear indication of when the belt moves above the pelvis. 
Loose clothing can make it difficult to determine where the top of the 
pelvis is, and in turn make it hard to discern exactly when the belt 
moved above it. This can be improved by marking the top of the pelvis 
clearly and by positioning the cameras so that

[[Page 18345]]

the position of the belt, relative to the top of the pelvis can be 
observed throughout the test (see Figure 3).
    (b) A measurement of the belt tension during the time when the belt 
moves above the pelvis. Place the webbing transducer to measure the 
total tension in the forward lap belt segment. If a split (combined 
body-centered and conventional) leading belt is used, measure the 
tension in the common section so that it reflects the contribution of 
each segment. Since this placement typically produces contact between 
the ATD and the transducer, it is important to use a webbing transducer 
that is not sensitive to contact.
    (c) Record useful video and belt load data until significant ATD 
rebound motion stops. Extra recording time is necessary because 
submarining usually occurs later in the test than other injury criteria 
maximums. To completely capture ATD rebound, the necessary time could 
exceed 500 ms.
    h. Occupant (ES-2re ATD) support:
    (1) Pelvis excursion: The load-bearing portion of the bottom of the 
ATD pelvis must not translate beyond the edges of its seat's bottom 
seat-cushion supporting structure.
    (2) Upper-torso support: The lateral flexion of the ATD torso must 
not exceed 40 degrees from the normal upright position during the 
impact.
    3. For all airbag systems in the shoulder harness and for leg 
flail, the following apply:
    a. Show that the airbag system will deploy and provide protection 
under crash conditions where it is necessary to prevent serious injury.
    b. The means of protection must take into consideration a range of 
stature from a 2-year-old child to a 95th percentile male.
    c. The airbag system must provide adequate protection for each 
occupant regardless of the number of occupants of the seat assembly, 
considering that unoccupied seats may have an active airbag system.
    d. It must be shown that the airbag system is not susceptible to 
inadvertent deployment as a result of wear and tear, or inertial loads 
resulting from in-flight or ground maneuvers (including gusts and hard 
landings), and other operating and environmental conditions 
(vibrations, moisture, etc.) likely to occur in service.
    e. Deployment of the airbag system must not introduce injury 
mechanisms to the seated occupant, or result in injuries that could 
impede rapid egress. This assessment should include an occupant whose 
seat belt is loosely fastened.
    f. It must be shown that inadvertent deployment of the airbag 
system, during the most critical part of the flight, will either meet 
the requirement of Sec.  25.1309(b) or not cause a hazard to the 
airplane or its occupants.
    g. It must be shown that the airbag system will not impede rapid 
egress of occupants 10 seconds after airbag deployment.
    h. The airbag system must be protected from lightning and high-
intensity radiated fields (HIRF). The threats to the airplane specified 
in existing regulations regarding lighting, Sec.  25.1316, and HIRF, 
Sec.  25.1317, are adopted by reference for the purpose of measuring 
lightning and HIRF protection.
    i. The airbag system must function properly after loss of normal 
aircraft electrical power, and after a transverse separation of the 
fuselage at the most critical location. A separation at the location of 
the airbag system does not have to be considered.
    j. It must be shown that the airbag system will not release 
hazardous quantities of gas or particulate matter into the cabin.
    k. The airbag system installation must be protected from the 
effects of fire such that no hazard to occupants will result.
    l. A means must be available for a crewmember to verify the 
integrity of the airbag system prior to each flight, or it must be 
demonstrated to reliably operate between inspection intervals. The FAA 
considers that the loss of the airbag-system deployment function alone 
(i.e., independent of the conditional event that requires the airbag-
system deployment) is a major-failure condition.
    m. The inflatable material may not have an average burn rate of 
greater than 2.5 inches/minute when tested using the horizontal 
flammability test defined in part 25, appendix F, part I, paragraph 
(b)(5).
    n. The airbag system, once deployed, must not adversely affect the 
emergency-lighting system (i.e., block floor proximity lights to the 
extent that the lights no longer meet their intended function).
    o. The airbag system must perform its intended function after 
impact from other proximate assemblies (e.g., life raft) that may 
become detached under the loads specified in Sec. Sec.  25.561 and 
25.562.
    4. For seats with an airbag system in the shoulder belts, the 
following apply:
    a. The airbag system in the shoulder belt must provide a consistent 
approach to energy absorption throughout that range of occupants. The 
airbag system must be included in each of the certification tests as it 
would be installed in the airplane. In addition, the following 
situations must be considered:
    (1) The seat occupant is holding an infant.
    (2) The seat occupant is a pregnant woman.
    b. The design must prevent the airbag system in the shoulder belt 
from being either incorrectly buckled or incorrectly installed, such 
that the airbag system in the shoulder belt would not properly deploy. 
Alternatively, it must be shown that such deployment is not hazardous 
to the occupant, and will provide the required injury protection.
    5. For seats using an airbag system to meet the leg-flail 
conditions of 2.e. the following apply:
    a. At some buttock popliteal length and effective seat bottom depth 
the lower legs will not be able to make a 90-degree angle with the 
upper leg; at this point the lower leg flail would not occur. The leg 
flail airbag system must provide a consistent approach to prevention of 
leg flail throughout that range of occupants whose lower legs can make 
a 90-degree angle with the upper legs when seated upright in the seat. 
Items that need to be considered include, but are not limited to the 
range of occupants' popliteal height, the range of occupants' buttock 
popliteal length, the design of the seat effective height above the 
floor, and the effective depth of the seat bottom cushion.
    b. For all g-levels, if the design of the leg flail limited device 
does absorb some of the impact energy and returns only a portion to the 
legs (a qualitative assessment), then a rebound leg flail of greater 
than 35 degrees is acceptable.
    c. Threshold test severity must be shown to be non-injurious (less 
than the post-mortem human subject (PMHS) low-g research testing) for 
g-levels up to the point where the leg flail airbag is designed to 
deploy.
BILLING CODE 4910-13-P

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    Issued in Kansas City, Missouri, on March 6, 2024.
James David Foltz,
Manager, Technical Policy Branch, Policy and Standards Division, 
Aircraft Certification Service.
[FR Doc. 2024-05226 Filed 3-12-24; 8:45 am]
BILLING CODE 4910-13-C