[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
[email protected].
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
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[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