[Federal Register Volume 89, Number 22 (Thursday, February 1, 2024)]
[Proposed Rules]
[Pages 6443-6450]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-02043]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2023-2435; Notice No. 25-23-07-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: Notice of proposed special conditions.

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SUMMARY: This action proposes special conditions 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 proposed 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: Send comments on or before February 21, 2024.

ADDRESSES: Send comments identified by Docket No. FAA-2023-2435 using 
any of the following methods:
    Federal eRegulations Portal: Go to https://www.regulations.gov/ and 
follow the online instructions for sending your comments 
electronically.
    Mail: Send comments to Docket Operations, M-30, U.S. Department of 
Transportation (DOT), 1200 New Jersey Avenue SE, Room W12-140, West 
Building Ground Floor, Washington, DC 20590-0001.
    Hand Delivery or Courier: Take comments to Docket Operations in 
Room W12-140 of the West Building Ground Floor at 1200 New Jersey 
Avenue SE, Washington, DC, between 9 a.m. and 5 p.m., Monday through 
Friday, except Federal holidays.
    Fax: Fax comments to Docket Operations at 202-493-2251.
    Docket: Background documents or comments received may be read at 
https://www.regulations.gov/ at any time. Follow the online 
instructions for accessing the docket or go to Docket Operations in 
Room W12-140 of the West Building Ground Floor at 1200 New Jersey 
Avenue SE, Washington, DC, between 9 a.m. and 5 p.m., Monday through 
Friday, except Federal holidays.

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 
<a href="/cdn-cgi/l/email-protection#6d20141f0c43274326180e062d0b0c0c430a021b"><span class="__cf_email__" data-cfemail="86cbfff4e7a8cca8cdf3e5edc6e0e7e7a8e1e9f0">[email protected]</span></a>.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    The FAA invites interested people to take part in this rulemaking 
by sending written comments, data, or views. The most helpful comments 
reference a specific portion of the proposed special conditions, 
explain the reason for any recommended change, and include supporting 
data.
    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. While the comment period provided by the FAA for 
proposed special conditions has typically been thirty days, the FAA is 
providing twenty days in this instance, due to the relative similarity 
of these conditions with the terms of previously issued special 
conditions, and due to the pendency of the anticipated delivery date 
for the affected airplane models, per the criteria in 14 CFR 11.38.
    The FAA will consider all comments received by the closing date for 
comments, and will consider comments filed late if it is possible to do 
so without incurring delay. The FAA may change these special conditions 
based on the comments received.

Privacy

    Except for Confidential Business Information (CBI) as described in 
the following paragraph, and other information as described in title 
14, Code of Federal Regulations (14 CFR) 11.35, the FAA will post all 
comments received without change to https://www.regulations.gov/, 
including any personal information you provide. The FAA will also post 
a report summarizing each substantive verbal contact received about 
these special conditions.

Confidential Business Information

    Confidential Business Information (CBI) is commercial or financial 
information that is both customarily and actually treated as private by 
its owner. Under the Freedom of Information Act (FOIA) (5 U.S.C. 552), 
CBI is exempt from public disclosure. If your comments responsive to 
these proposed special conditions contain commercial or financial 
information that is customarily treated as private, that you actually 
treat as private, and that is relevant or responsive to these special 
conditions, it is important that you clearly designate the submitted 
comments as CBI. Please mark each page of your submission containing 
CBI as ``PROPIN.'' The FAA will treat such marked submissions as 
confidential under the FOIA, and the indicated comments will not be 
placed in the public docket of these special conditions. Send 
submissions containing CBI to the individual listed in the For Further 
Information Contact section above. Comments the FAA receives, which are 
not specifically designated as CBI, will be placed in the public docket 
for these special conditions.

Background

    As noted above, on December 31, 2019, Gulfstream applied for an 
amendment to Type Certificate No.

[[Page 6444]]

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.
    If the Administrator finds that the applicable airworthiness 
regulations (e.g., 14 CFR part 25) 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 Features

    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, Title 14, Code of Federal Regulations (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 \2\ 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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    \2\ See, generally, Exemption Nos. 7120C, 7878A, 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 
\3\). 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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    \3\ Document available 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 addresses 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 proposed 
special conditions. Some of the conditions issued for previous 
exemptions are still relevant and are included in these proposed 
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 proposed 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.

Applicability

    As discussed above, these proposed 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.

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, and 
44704.

[[Page 6445]]

The Proposed Special Conditions

    [ssquf] 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 proposes 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, whereas item 4 would 
impose requirements applicable to side-facing seats equipped with an 
airbag system in the shoulder belt, and item 5 would impose 
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 1a, 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 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

[[Page 6446]]

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. A 250 lb. 
lap belt tension limit based upon the findings in Civil Aerospace 
Medical Institute (CAMI) report DOT/FAA/AM-17/02. The data should be 
filtered at CFC 60 as defined in SAE J211. In order to complete the 
evaluation using this tension criteria, three things are needed.
    1. 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 the position of the 
belt, relative to the top of the pelvis can be observed throughout the 
test (see Figure 3).
    2. A measurement of the belt tension during the time when the belt 
moves above the pelvis. The webbing transducer should be placed to 
measure the total tension in the forward lap belt segment. If a split 
(combined body-centered and conventional) leading belt is used, the 
tension should be measured 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.
    3. Useful video and belt load data must be recorded 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

[[Page 6447]]

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

[[Page 6448]]

[GRAPHIC] [TIFF OMITTED] TP01FE24.114


[[Page 6449]]


[GRAPHIC] [TIFF OMITTED] TP01FE24.115

[GRAPHIC] [TIFF OMITTED] TP01FE24.116



[[Page 6450]]


    Issued in Kansas City, Missouri, on January 29, 2024.
Patrick R. Mullen,
Manager, Technical Innovation Policy Branch, Policy and Innovation 
Division, Aircraft Certification Service.
[FR Doc. 2024-02043 Filed 1-29-24; 5:00 pm]
BILLING CODE 4910-13-C


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