Rule2023-17403
Special Conditions: The Boeing Company Model 737-10 Airplane; Dynamic Test Requirements for Single Occupant Oblique Seats With or Without Airbags and/or 3-Point Restraints
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Published
August 15, 2023
Effective
August 15, 2023
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
These special conditions are issued for The Boeing Company (Boeing) Model 737-10 series airplane. This airplane 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 oblique (side-facing) single-occupant seats equipped with airbag devices or 3-point restraints. 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.
Full Text
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<title>Federal Register, Volume 88 Issue 156 (Tuesday, August 15, 2023)</title>
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[Federal Register Volume 88, Number 156 (Tuesday, August 15, 2023)]
[Rules and Regulations]
[Pages 55359-55362]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2023-17403]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2023-1467; Special Conditions No. 25-840-SC]
Special Conditions: The Boeing Company Model 737-10 Airplane;
Dynamic Test Requirements for Single Occupant Oblique Seats With or
Without Airbags and/or 3-Point Restraints
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions; request for comments.
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SUMMARY: These special conditions are issued for The Boeing Company
(Boeing) Model 737-10 series airplane. This airplane 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 oblique (side-facing) single-occupant
seats equipped with airbag devices or 3-point restraints. 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: This action is effective on Boeing on August 15, 2023. Send
comments on or before September 29, 2023.
ADDRESSES: Send comments identified by Docket No. FAA-2023-1467 using
any of the following methods:
<bullet> Federal eRegulations Portal: Go to <a href="https://www.regulations.gov/">https://www.regulations.gov/</a> and follow the online instructions for sending
your comments electronically.
<bullet> 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.
<bullet> Hand Delivery or Courier: Take comments to Docket
Operations in Room W12-140 of the West Building Ground Floor at 1200
New Jersey
[[Page 55360]]
Avenue SE, Washington, DC, between 9 a.m. and 5 p.m., Monday through
Friday, except Federal holidays.
<bullet> Fax: Fax comments to Docket Operations at 202-493-2251.
<bullet> Docket: Background documents or comments received may be
read at <a href="https://www.regulations.gov/">https://www.regulations.gov/</a> 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: John Shelden, Cabin Safety Section,
AIR-624, Technical Policy Branch, Policy and Standards Division,
Aircraft Certification Service, Federal Aviation Administration, 2200
South 216th Street, Des Moines, Washington 98198; telephone and fax
206-231-3214; email <a href="/cdn-cgi/l/email-protection#0a406562642459626f666e6f644a6c6b6b246d657c"><span class="__cf_email__" data-cfemail="62280d0a0c4c310a070e06070c220403034c050d14">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
The substance of these special conditions has been published in the
Federal Register for public comment in several prior instances with no
substantive comments received. Therefore, the FAA finds, pursuant to 14
CFR 11.38(b), that new comments are unlikely, and notice and comment
prior to this publication are unnecessary.
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 <a href="https://www.regulations.gov/">https://www.regulations.gov/</a>,
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
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 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 John Shelden,
Cabin Safety Section, AIR-624, Technical Policy Branch, Policy and
Standards Division, Aircraft Certification Service, Federal Aviation
Administration, 2200 South 216th Street, Des Moines, Washington 98198;
telephone and fax 206-231-3214; email <a href="/cdn-cgi/l/email-protection#80caefe8eeaed3e8e5ece4e5eec0e6e1e1aee7eff6"><span class="__cf_email__" data-cfemail="1d57727573334e7578717978735d7b7c7c337a726b">[email protected]</span></a>. Comments
the FAA receives, which are not specifically designated as CBI, will be
placed in the public docket for these special conditions.
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 special conditions, explain the
reason for any recommended change, and include supporting data.
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.
Background
On October 28, 2022, Boeing applied for a change to Type
Certificate No. A16WE for the installation of oblique (side-facing)
passenger seats with or without airbag devices or 3-point restraints in
the Boeing Model 737-10 series airplanes. The Boeing Model 737-10
series airplanes are twin-engine, transport category airplanes with a
maximum certified passenger capacity of up to 230, and a maximum
takeoff weight of approximately 197,900 lbs.
Type Certification Basis
Under the provisions of title 14, Code of Federal Regulations (14
CFR) 21.101, Boeing must show that the Model 737-10 series airplanes,
as changed, continue to meet the applicable provisions of the
regulations listed in Type Certificate No. A16WE 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 Boeing Model 737-10 series
airplane 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, the special conditions would also apply to the
other model under Sec. 21.101.
In addition to the applicable airworthiness regulations and special
conditions, the Boeing Model 737-10 series airplane 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 Sec. 11.38, and they become part of the type
certification basis under Sec. 21.101.
Novel or Unusual Design Features
The Boeing Model 737-10 series airplane will incorporate a seating
configuration that is novel or unusual due to the installation of
oblique (side-facing) passenger seats and surrounding furniture that
introduces occupant alignment and loading concerns. These oblique seats
may be installed at an angle of 18 to 45 degrees to the aircraft
centerline and may include a 3-point restraint system and/or airbags,
for occupant restraint and injury protection.
Discussion
Title 14, Code of Federal Regulations (14 CFR) 25.785(d) requires
that each occupant of a seat that makes more than an 18 degree angle
with the vertical plane containing the airplane centerline must be
protected from head injury by a safety belt and an energy absorbing
rest that will support the arms, shoulders, head, and spine, or by a
safety belt and shoulder harness that will prevent the head from
contacting any injurious object.
The proposed Boeing Model 737-10 airplane seat installation is
novel in that the current requirements do not adequately address
protection of the occupant's neck and spine for seating configurations
that are positioned at angles greater than 18 degrees up to and
including 45 degrees from the airplane centerline. The installation of
passenger seats at angles of 18 to 45 degrees to the airplane
centerline is unique due to the seat/occupant interface with the
surrounding furniture that introduces occupant alignment/loading
concerns with or without the installation of a 3-point or airbag
restraint system, or both.
[[Page 55361]]
In order to provide a level of safety that is equivalent to that
afforded to occupants of forward and aft facing seating, additional
airworthiness standards, in the form of new special conditions, are
necessary.
The FAA has been conducting and sponsoring research on appropriate
injury criteria for oblique (side-facing) seat installations. To
reflect current research findings, the FAA issued policy statement PS-
AIR-25-27. FAA-sponsored research has found that an un-restrained
flailing of the upper torso, even when the pelvis and torso are nearly
aligned, can produce serious spinal and torso injuries. At lower impact
severities, even with significant misalignment between the torso and
pelvis, these injuries did not occur. Tests with an FAA H-III
anthropomorphic test dummy (ATD) have identified a level of lumbar
spinal tension corresponding to the no-injury impact severity. This
level of tension is included as a limit in the special conditions. The
spine tension limit selected is conservative with respect to other
aviation injury criteria since it corresponds to a no-injury loading
condition.
As noted in the special conditions for each airbag restraint
system, because an airbag restraint system is essentially a single use
device, there is the potential that it could deploy under crash
conditions that are not sufficiently severe as to require head injury
protection from the airbag restraint system. Since an actual crash is
frequently composed of a series of impacts before the airplane comes to
rest, this could render the airbag restraint system useless if a larger
impact follows the initial impact. This situation does not exist with
energy absorbing pads or upper torso restraints, which tend to provide
protection according to the severity of the impact. Therefore, the
installation of the airbag restraint system should be such that the
airbag restraint system will provide protection when it is required,
and will not expend its protection when it is not needed.
Because these airbag restraint systems may or may not activate
during various crash conditions, the injury criteria listed in these
special conditions and in Sec. 25.562 must be met in an event that is
slightly below the activation level of the airbag restraint system. If
an airbag restraint system is included with the oblique seats, the
system must meet the requirements in one of the airbag (inflatable
restraint) special conditions applicable to the Boeing Model 737 series
airplanes. These special conditions supplement part 25 and, more
specifically, supplement Sec. Sec. 25.562 and 25.785.
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.
Applicability
As discussed above, these special conditions are applicable to the
Boeing Model 737-10 series airplane. Should Boeing 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 that model as well.
Conclusion
This action affects only a certain novel or unusual design feature
on one model 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.
The Special Conditions
0
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 The Boeing Company Model 737-10 series
airplanes.
In addition to the requirements of Sec. 25.562, passenger seats
installed at an angle between 18 degrees and 45 degrees from the
aircraft centerline must meet the following:
1. Head Injury Criteria (HIC)
Compliance with Sec. 25.562(c)(5) is required, except that, if the
anthropomorphic test dummy (ATD) has no apparent contact with the seat/
structure but has contact with an airbag, a HIC unlimited score in
excess of 1000 is acceptable, provided the HIC15 score (calculated in
accordance with 49 CFR 571.208) for that contact is less than 700.
2. Body-to-Wall/Furnishing Contact
If a seat is installed aft of structure (e.g., interior wall or
furnishings) that does not provide a homogenous contact surface for the
expected range of occupants and yaw angles, then additional analysis
and tests may be required to demonstrate that the injury criteria are
met for the area that an occupant could contact. For example, if
different yaw angles could result in different airbag device
performance, then additional analysis or separate tests may be
necessary to evaluate performance.
3. Neck Injury Criteria
The seating system must protect the occupant from experiencing
serious neck injury. The assessment of neck injury must be conducted
with the airbag device activated, unless there is reason to also
consider that the neck-injury potential would be higher for impacts
below the airbag-device deployment threshold.
a. The N<INF>ij</INF> (calculated in accordance with 49 CFR
571.208) must be below 1.0, where N<INF>ij</INF> = F<INF>z</INF>/
F<INF>zc</INF> + M<INF>y</INF>/M<INF>yc</INF>, and N<INF>ij</INF>
critical values are:
i. F<INF>zc</INF> = 1530 lbs. for tension
ii. F<INF>zc</INF> = 1385 lbs. for compression
iii. M<INF>yc</INF> = 229 lb-ft in flexion
iv. M<INF>yc</INF> = 100 lb-ft in extension
b. In addition, peak F<INF>z</INF> must be below 937 lbs. in
tension and 899 lbs. in compression.
c. Rotation of the head about its vertical axis relative to the
torso is limited to 105 degrees in either direction from forward
facing.
d. The neck must not impact any surface that would produce
concentrated loading on the neck.
4. Spine and Torso Injury Criteria
a. The lumbar spine tension (F<INF>z</INF>) cannot exceed 1200 lbs.
b. Significant concentrated loading on the occupant's spine, in the
area between the pelvis and shoulders during impact, including rebound,
is not acceptable. During this type of contact, the interval for any
rearward (X direction) acceleration exceeding 20g must be less than 3
milliseconds as measured by the thoracic instrumentation specified in
49 CFR part 572, subpart E filtered in accordance with SAE
International (SAE) recommended practice J211/1, ``Instrumentation for
Impact Test--Part 1--Electronic Instrumentation.''
c. The occupant must not interact with the armrest or other seat
components in any manner significantly different than would be expected
for a forward-facing seat installation.
5. Pelvis Criteria
Any part of the load-bearing portion of the bottom of the ATD
pelvis must not translate beyond the edges of the
[[Page 55362]]
seat bottom seat-cushion supporting structure.
6. Femur Criteria
Axial rotation of the upper leg (about the z-axis of the femur per
SAE Recommended Practice J211/1) must be limited to 35 degrees from the
nominal seated position. Evaluation during rebound does not need to be
considered.
7. ATD and Test Conditions
Longitudinal tests conducted to measure the injury criteria above
must be performed with the FAA Hybrid III ATD, as described in SAE
1999-01-1609, ``A Lumbar Spine Modification to the Hybrid III ATD for
Aircraft Seat Tests.'' The tests must be conducted with an undeformed
floor, at the most-critical yaw cases for injury, and with all lateral
structural supports (e.g., armrests or walls) installed.
Note: Boeing must demonstrate that the installation of seats
via plinths or pallets meets all applicable requirements. Compliance
with the guidance contained in policy memorandum PS-ANM-100-2000-
00123, ``Guidance for Demonstrating Compliance with Seat Dynamic
Testing for Plinths and Pallets,'' dated February 2, 2000, is
acceptable to the FAA.
8. Inflatable Airbag Restraint Systems Special Conditions
If inflatable airbag restraint systems are installed, the airbag
systems must meet the requirements in special conditions 25-386-SC, or
other airbag system special conditions which are applicable to the
Boeing Model 737 series airplanes.
Issued in Des Moines, WA, on August 9, 2023.
Paul R. Siegmund,
Acting Manager, Technical Policy Branch, Policy and Standards Division,
Aircraft Certification Service.
[FR Doc. 2023-17403 Filed 8-14-23; 8:45 am]
BILLING CODE 4910-13-P
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