Special Conditions: The Boeing Company, Model 737-10 Airplane; Dynamic Test Requirements for Single-Occupant, Oblique (Side-Facing) Seats Installed at 49 Degrees With Airbag Devices and 3-Point Restraints, 8147-8150 [2022-03012]
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Federal Register / Vol. 87, No. 30 / Monday, February 14, 2022 / Rules and Regulations
applied during ‘‘normal’’ control law
within the speed range, from initiation
of the angle-of-attack protection limit,
Vprot, to VMO/MMO. Once outside this
speed range, the control laws introduce
the conventional longitudinal static
stability as described above.
As a result of neutral static stability,
the Model Falcon 6X airplane does not
meet the regulatory requirements for
static longitudinal stability.
3. Low Energy Awareness
Past experience on airplanes fitted
with a flight-control system providing
neutral longitudinal stability reveals
insufficient feedback cues to the pilot of
excursion below normal operational
speeds. The maximum angle-of-attack
protection system limits the airplane
angle of attack and prevents stall during
normal operating speeds, but this
system is not sufficient to prevent stall
at low-speed excursions below normal
operational speeds. Until intervention,
there are no stability cues because the
aircraft remains trimmed. Additionally,
feedback from the pitching moment due
to thrust variation is reduced by the
flight-control laws. Low-speed
excursions may become more hazardous
without the typical longitudinal
stability, and recovery is more difficult
when the low-speed situation is
associated with a low altitude, and with
the engines at low thrust or with
performance-limiting conditions.
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 Dassault
Model Falcon 6X airplane. Should
Dassault apply at a later date for a
change to the type certificate to include
another model incorporating the same
novel or unusual design feature, these
special conditions would apply to that
model as well.
Conclusion
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This action affects only a certain
novel or unusual design feature on one
model of airplane. 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:
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Authority: 49 U.S.C. 106(f), 106(g), 40113,
44701, 44702, 44704.
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 Dassault
Aviation Model Falcon 6X airplane.
In lieu of the requirements of
§§ 25.171, 25.173, 25.175, and 25.177(c),
the following special conditions apply:
1. The airplane must be shown to
have suitable static lateral, directional,
and longitudinal stability in any
condition normally encountered in
service, including the effects of
atmospheric disturbance. The showing
of suitable static lateral, directional, and
longitudinal stability must be based on
the airplane handling qualities,
including pilot workload and pilot
compensation, for specific test
procedures during the flight-test
evaluations.
2. The airplane must provide
adequate awareness to the pilot of a low
energy (low speed, low thrust, low
height) state when fitted with flightcontrol laws presenting neutral
longitudinal stability significantly
below the normal operating speeds.
‘‘Adequate awareness’’ means warning
information must be provided to alert
the crew of unsafe operating conditions,
and to enable them to take appropriate
corrective action.
3. The following requirement must be
met for the configurations and speed
specified in paragraph (a) of § 25.177. In
straight, steady sideslips over the range
of sideslip angles appropriate to the
operation of the airplane, the ruddercontrol movements and forces must be
substantially proportional to the angle
of sideslip in a stable sense. This factor
of proportionality must lie between
limits found necessary for safe
operation. The range of sideslip angles
evaluated must include those sideslip
angles resulting from the lesser of:
a. One-half of the available rudder
control input; and
b. A rudder control force of 180
pounds.
Issued in Kansas City, Missouri, on
February 8, 2022.
Patrick R. Mullen,
Manager, Technical Innovation Policy
Branch, Policy and Innovation Division,
Aircraft Certification Service.
[FR Doc. 2022–03026 Filed 2–11–22; 8:45 am]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
The Special Conditions
BILLING CODE 4910–13–P
8147
14 CFR Part 25
[Docket No. FAA–2021–1023; Special
Conditions No. 25–811–SC]
Special Conditions: The Boeing
Company, Model 737–10 Airplane;
Dynamic Test Requirements for SingleOccupant, Oblique (Side-Facing) Seats
Installed at 49 Degrees With Airbag
Devices and 3-Point Restraints
Federal Aviation
Administration (FAA), Department of
Transportation (DOT).
ACTION: Final special conditions.
AGENCY:
These special conditions are
issued for The Boeing Company
(Boeing) Model 737–10 airplane. This
airplane will have a novel or unusual
design feature when compared to the
state of technology envisioned in the
airworthiness standards for transportcategory airplanes. This design feature
is single-occupant oblique seats with
airbag devices and 3-point restraints,
installed at 49 degrees relative to the
airplane cabin bow-to-stern centerline.
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 February 14, 2022.
FOR FURTHER INFORMATION CONTACT: John
Shelden, Human Machine Interface
Section, AIR–626, Technical Innovation
Policy Branch, Policy and Innovation
Division, Aircraft Certification Service,
Federal Aviation Administration, 2200
South 216th Street, Des Moines,
Washington 98198; telephone and fax
206–231–3214; email john.shelden@
faa.gov.
SUMMARY:
SUPPLEMENTARY INFORMATION:
Background
On January 30, 2019, Boeing applied
for a change to Type Certificate No.
A16WE for the installation of singleoccupant oblique seats, with airbag
devices and 3-point restraints, installed
at 49 degrees relative to the airplane
cabin bow-to-stern centerline in the
Boeing Model 737–10 airplane. The
Boeing Model 737–10 airplane is a twinengine, transport-category airplane with
seating for 230 passengers and a
maximum takeoff weight of 197,900
pounds.
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Type Certification Basis
Under the provisions of 14 CFR
21.101, Boeing must show that the
Model 737–10 airplane, as changed,
continues 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 airplane
because of a novel or unusual design
feature, special conditions are
prescribed under the provisions of
§ 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 § 21.101.
In addition to the applicable
airworthiness regulations and special
conditions, the Boeing Model 737–10
airplane must comply with the fuel-vent
and exhaust-emission requirements of
14 CFR part 34, and the noisecertification requirements of 14 CFR
part 36.
The FAA issues special conditions, as
defined in § 11.19, in accordance with
§ 11.38, and they become part of the
type certification basis under § 21.101.
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Novel or Unusual Design Features
The Boeing Model 737–10 airplane
will incorporate the following novel or
unusual design feature:
Single-occupant oblique seats, with
airbag devices and 3-point restraints,
installed at 49 degrees relative to the
airplane cabin bow-to-stern centerline.
Discussion
Section 25.785(d) requires that each
occupant of a seat installed at an angle
of more than 18 degrees, relative to bowto-stern airplane cabin centerline, must
be protected from head injury using a
seatbelt and an energy-absorbing rest
that supports the arms, shoulders, head,
and spine; or using a seatbelt and
shoulder harness designed to prevent
the head from contacting any injurious
object.
The Boeing Model 737–10 airplane
single-occupant oblique seat
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installation, with airbag devices and 3point restraints, is novel such that the
current requirements do not adequately
address airbag devices and protection of
the occupant’s neck, spine, torso, and
legs for seating configurations that are
positioned at an angle of 49 degrees
from the airplane centerline. The seating
configuration installation angle is
beyond the installation-design limits of
current special conditions issued for
seat positions at angles between 18
degrees and 45 degrees. For example, at
these angles, lateral neck bending and
other injury mechanisms prevalent from
a fully side-facing installation become a
concern. Although special conditions
no. 25–552–SC was issued for Boeing
Model 787 airplane seats installed at 49
degrees in 2014, that document is no
longer applicable because they were
issued prior to the current oblique-seat
special conditions that are based on the
July 11, 2018, FAA policy statement PS–
AIR–25–27, ‘‘Technical Criteria for
Approving Oblique Seats.’’ These
special conditions are based on the
Boeing Model 787 airplane special
conditions, with updates from that
policy statement, and to align with the
fully side-facing-seat policy statement
PS–ANM–25–03–R1, ‘‘Technical
Criteria for Approving Side-Facing
Seats.’’
To provide a level of safety equivalent
to that afforded to occupants of forwardand aft-facing seats, additional
airworthiness standards, in the form of
dynamic testing requirements, including
both the injury criteria limits from the
oblique-seat policy and the fully sidefacing-seat policy through new special
conditions, are necessary.
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. 25–21–05–SC
for the Boeing Model 737–10 airplane,
which was published in the Federal
Register on December 15, 2021 (86 FR
71183). The FAA received one comment
from the Air Line Pilots Association,
International, in support of the special
conditions.
Applicability
As discussed above, these special
conditions are applicable to the Boeing
Model 737–10 airplane. Should Boeing
apply at a later date for a change to the
type certificate to include another
model incorporating the same novel or
unusual design feature, these special
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conditions would apply to that model as
well.
Conclusion
This action affects only a certain
novel or unusual design feature on one
model of airplane. 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 Boeing Model
737–10 airplanes.
In addition to the requirements of
§§ 25.562 and 25.785, passenger seats
with airbag devices and 3-point
restraints, installed at an angle 49
degrees relative to the airplane cabin
bow-to-stern centerline, must meet the
following:
a. Head Injury Criteria (HIC)
HIC assessments are required only for
head contact with the seat and other
structure.
1. Compliance with § 25.562(c)(5) is
required, except that, because an airbag
device is present in addition to the 3point restraint system, when the
anthropomorphic test dummy (ATD)
has no apparent contact with the seat
and other structure but has contact with
the airbag, a HIC 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. ATD head contact with the seat or
other structure through the airbag, or
contact subsequent to contact with the
airbag, requires an HIC value not
exceeding 1000.
3. The HIC value must not exceed
1000 in any condition in which the
airbag does or does not deploy, up to the
maximum severity pulse specified by
the existing requirements.
4. To accommodate a range of
occupant heights (5th percentile female
to 95th percentile male), any surface,
airbag or otherwise, that provides
support for the occupant head, must
provide that support in a consistent
manner regardless of occupant stature.
Otherwise, additional HIC assessment
tests may be needed.
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b. Body-to-Wall/Furnishing Contact
If a seat is installed aft of structure,
such as an interior wall or furnishing
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 an occupant
could contact. For example, different
yaw angles could result in different
injury considerations and airbag
performance, and may require
additional analysis, or separate tests
may be necessary to evaluate
performance.
c. Neck Injury Criteria
1. 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.
2. Rotation of the head about its
vertical axis, relative to the torso, is
limited to 105 degrees in either
direction from forward-facing.
3. The neck must not impact any
surface that would produce
concentrated loading on the neck.
4. Assess neck injury for fore and aft
neck bending using 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,’’ applying the following criteria:
The Nij, calculated in accordance with
49 CFR 571.208, must be below 1.0,
where Nij = Fz/Fzc + My/Myc, and Nij
critical values are:
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Fzc = 1,530 lbs (6805 N) for tension
Fzc = 1,385 lbs (6160 N) for compression
Myc = 229 lb-ft (301 Nm) in flexion
Myc = 100 lb-ft (136 Nm) in extension
In addition, peak upper-neck Fz must
be below 937 lbs (4168 N) in tension
and 899 lbs (3999 N) in compression.
5. When lateral neck bending is
present, assess it using an ES–2re ATD
as defined by 49 CFR part 572, subpart
U. The data must be filtered at channel
frequency class (CFC) 600 as defined in
SAE Recommended Practice J211–1,
‘‘Instrumentation for Impact Test Part
1—Electrionic Instrumentation:’’
i. The upper-neck tension force at the
occipital condyle (O.C.) location must
be less than 405 lbs (1,800 N).
ii. The upper-neck compression force
at the O.C. location must be less than
405 lbs (1,800 N).
iii. The upper-neck bending torque
about the ATD x-axis at the O.C.
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location must be less than 1,018 in-lbs
(115 Nm).
iv. The upper-neck resultant shear
force at the O.C. location must be less
than 186 lbs (825 N).
d. Spine and Torso Injury Criteria
1. The seating system must protect the
occupant from experiencing spine and
torso injury. The assessment of spine
and torso injury must be conducted
with the airbag device activated, unless
it is necessary to also consider that the
occupant-injury potential would be
higher for impacts below the airbagdevice deployment threshold.
2. Assess spine and torso injury, for
oblique torso bending, using the FAA
Hybrid III ATD, applying the following
criteria:
i. The lumbar spine tension (Fz)
cannot exceed 1,200 lbs (5338 N).
ii. 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 Recommended
Practice J211–1.
3. When lateral torso bending is
present, assess spine and torso injury
using an ES–2re ATD, applying the
following criteria:
i. Thoracic: The deflection of any of
the ES–2re ATD upper, middle, and
lower ribs must not exceed 1.73 inches
(44 mm). Process the data as defined in
Federal Motor Vehicle Safety Standards
(FMVSS) 571.214, title 49 of the CFR.
ii. Abdominal: The sum of the
measured ES–2re ATD front, middle,
and rear abdominal forces must not
exceed 562 lbs (2,500 N). Process the
data as defined in FMVSS 571.214.
iii. Upper-torso support: The lateral
flexion of the ATD torso must not
exceed 40 degrees from the normal
upright positions during impact.
e. Pelvic Criteria
1. The seating system must protect the
occupant from experiencing pelvis
injury.
2. Any part of the load-bearing
portion of the bottom of the ATD pelvis
must not translate beyond the edges of
the seat bottom seat-cushion supporting
structure.
3. When pelvis contact with the
armrest or surrounding interior
components is present, assess it using
an ES–2re ATD. The pubic symphysis
force measured by the ES–2re ATD must
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8149
not exceed 1,350 lbs (6,000 N). Process
the data as defined in FMVSS 571.214.
f. Femur Criteria
Limit axial rotations of the upper leg
(about the z-axis of the femur, per SAE
Recommended Practice J211–1) to 35
degrees from the nominal seated
position. Evaluation during rebound
does not need to be considered.
g. ATD and Test Condition
1. Perform longitudinal tests,
conducted to measure the injury criteria
above, using the FAA Hybrid III ATD or
using the ES–2re ATD. Conduct the tests
with the undeformed floor, at the mostcritical yaw cases for injury, and with
all lateral structural supports (e.g.,
armrests or walls) installed.
2. For longitudinal tests conducted in
accordance with § 25.562(b)(2), to show
compliance with the seat-strength
requirements of § 25.562(c)(7) and (8),
and these special conditions, to ensure
proper loading of the seat by the
occupant, the ATD pelvis must remain
supported by the seat pan, and the
restraint system must remain on the
pelvis of the ATD until rebound begins.
No injury criteria evaluation is
necessary for tests conducted only to
assess seat-strength requirements.
3. If a seat installation includes
adjacent items that are within contact
range of an occupant, assess the injury
potential of that contact. To make this
assessment, tests may be conducted to
include the actual contact item, located
and attached in a representative fashion.
Alternatively, the injury potential may
be assessed through a combination of
tests with contact items having the same
geometry as the actual contact item, but
having stiffness characteristics that
would create the worst case for injury,
such as injuries due to both contact with
the item and lack of support from the
item.
4. Conduct the combined horizontal
and vertical test, required by
§ 25.562(b)(1) and these special
conditions, with the FAA Hybrid II ATD
(49 CFR part 572, subpart B, as specified
in § 25.562) or equivalent.
5. The design and installation of
seatbelt buckles must prevent
unbuckling due to applied inertial
forces, or impact from seat occupant
hands and arms, during an emergency
landing.
h. Inflatable Airbag-Restraint System
Special Conditions
An inflatable airbag-restraint system
will be installed, and must meet the
requirements of Special Conditions No.
25–386–SC, ‘‘Boeing Model 737–600/–
700/–700C/–800/–900 and 900ER Series
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Airplanes; Seats With Inflatable
Lapbelts,’’ applicable to Boeing Model
737–10 series airplanes.
i. General Test Guidelines
1. The determination of the
appropriate ATD to be used in assessing
occupant injury (FAA Hybrid III or ES–
2re) is based on the occupant kinematics
at the selected test angle. At the +10degree yaw angle, the occupant
kinematics show that occupant injury
tests, using both ATDs, are required.
2. Conduct vertical tests with the
Hybrid II ATD or equivalent, with
existing pass/fail criteria.
3. Conduct longitudinal structural
tests with the Hybrid II ATD or
equivalent, deformed floor, with 10
degrees yaw, and with all lateral
structural supports (e.g., armrests or
walls) required to support the occupant.
4. Conduct longitudinal occupantinjury tests, as necessary, with the FAA
Hybrid III ATD or ES–2re ATD,
undeformed floor, yaw, and with all
lateral structural supports (e.g., armrests
or walls) critically represented, and
which are within contact range of the
occupant.
i. Pass/fail injury assessments:
A. Perform HIC, fore and aft neck
injury, spinal tension, and femur
evaluations using the FAA Hybrid III
ATD.
B. Perform lateral neck injury,
thoracic, abdominal, pelvis, and femur
evaluations using the ES–2re ATD.
5. For injury assessments
accomplished by testing with the ES–
2re ATD for longitudinal tests
conducted in accordance with
§ 25.562(b)(2) and these special
conditions, the ATDs must be
positioned, clothed, and have lateral
instrumentation configured as follows:
i. 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). Install the modules such that
the moving end of the rib module is
toward the front of the airplane. Install
the three abdominal-force sensors such
that they are on the side of the ATD
toward the front of the airplane.
ii. ATD Clothing:
Clothe each ATD in form-fitting
cotton-stretch garments with short- to
full-length sleeves, mid-calf to fulllength pants, and size 11E (45) shoes
weighing about 2.5 lbs (1.1 kg), and
having a heel height of about 1.5 inches
(3.8 cm). The color of the clothing
should be in contrast to the color of the
restraint system and the background.
The color of the clothing should be
chosen to avoid overexposing the high-
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speed images captured during the test.
The ES–2re jacket is sufficient for torso
clothing, although a form-fitting shirt
may be used in addition, if desired.
iii. ATD Positioning:
A. Lower the ATD vertically into the
seat while simultaneously:
(1) Aligning the midsagittal plane (a
vertical plane through the midline of the
body, dividing the body into right and
left halves) to approximately the middle
of the seat place.
(2) Keeping the upper legs horizontal
by supporting them just behind the
knees.
(3) Applying a horizontal x-axis
direction (in the ES–2re ATD coordinate
system) force of about 20 lbs (89 N) to
the bottom rib of the ES–2re, to
compress the seat-back cushion.
B. After all lifting devices have been
removed from the ATD:
(1) Rock it slightly to settle it in the
seat.
(2) Bend the knees of the ATD.
(3) Separate the knees by about 4
inches (100 mm).
(4) Set the ATD’s head at
approximately the midpoint of the
available range of z-axis rotation (to
align the head and torso midsagittal
planes).
(5) Position the ATD’s arms at the
joints’ mechanical detent, to position
them to an approximately 20- to 40degree angle with respect to the torso.
(6) Position the feet such that the
centerlines of the lower legs are
approximately parallel.
Note: Seats installed via plinths or pallets
must meet 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.
Issued in Kansas City, Missouri, on
February 8, 2022.
Patrick R. Mullen,
Manager, Technical Innovation Policy
Branch, Policy and Innovation Division,
Aircraft Certification Service.
[FR Doc. 2022–03012 Filed 2–11–22; 8:45 am]
BILLING CODE 4910–13–P
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA–2021–0961; Project
Identifier MCAI–2021–00924–A; Amendment
39–21935; AD 2022–03–18]
RIN 2120–AA64
Airworthiness Directives; British
Aerospace (Operations) Limited and
British Aerospace Regional Aircraft
Airplanes
Federal Aviation
Administration (FAA), DOT.
ACTION: Final rule.
AGENCY:
The FAA is adopting a new
airworthiness directive (AD) for certain
British Aerospace (Operations) Limited
and British Aerospace Regional Aircraft
Model Jetstream Series 200, Jetstream
Model 3101, and Jetstream Model 3201
airplanes. This AD results from
mandatory continuing airworthiness
information (MCAI) originated by an
aviation authority of another country to
identify and correct an unsafe condition
on an aviation product. The MCAI
identifies the unsafe condition as a bent
control rod within the gust lock system,
which may enable both power levers to
be pushed into the flight range with the
gust lock lever fully engaged. This AD
requires replacing the push rod
assembly with a modified push rod
assembly. The FAA is issuing this AD
to address the unsafe condition on these
products.
DATES: This AD is effective March 21,
2022.
The Director of the Federal Register
approved the incorporation by reference
of a certain publication listed in this AD
as of March 21, 2022.
ADDRESSES: For service information
identified in this final rule, contact BAE
Systems (Operations) Ltd., Customer
Information Department, Prestwick
International Airport, Ayrshire, KA9
2RW, Scotland, United Kingdom;
phone: +44 3300 488727; fax: +44 1292
675704; email: RApublications@
baesystems.com; website: https://
www.baesystems.com/Businesses/
RegionalAircraft/. You may view this
service information at the FAA,
Airworthiness Products Section,
Operational Safety Branch, 901 Locust,
Kansas City, MO 64106. For information
on the availability of this material at the
FAA, call (817) 222–5110. It is also
available at https://www.regulations.gov
by searching for and locating Docket No.
FAA–2021–0961.
SUMMARY:
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]]>Agencies
[Federal Register Volume 87, Number 30 (Monday, February 14, 2022)]
[Rules and Regulations]
[Pages 8147-8150]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-03012]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2021-1023; Special Conditions No. 25-811-SC]
Special Conditions: The Boeing Company, Model 737-10 Airplane;
Dynamic Test Requirements for Single-Occupant, Oblique (Side-Facing)
Seats Installed at 49 Degrees With Airbag Devices and 3-Point
Restraints
AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (DOT).
ACTION: Final special conditions.
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SUMMARY: These special conditions are issued for The Boeing Company
(Boeing) Model 737-10 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 single-occupant oblique seats with
airbag devices and 3-point restraints, installed at 49 degrees relative
to the airplane cabin bow-to-stern centerline. 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 February 14, 2022.
FOR FURTHER INFORMATION CONTACT: John Shelden, Human Machine Interface
Section, AIR-626, Technical Innovation Policy Branch, Policy and
Innovation Division, Aircraft Certification Service, Federal Aviation
Administration, 2200 South 216th Street, Des Moines, Washington 98198;
telephone and fax 206-231-3214; email [email protected].
SUPPLEMENTARY INFORMATION:
Background
On January 30, 2019, Boeing applied for a change to Type
Certificate No. A16WE for the installation of single-occupant oblique
seats, with airbag devices and 3-point restraints, installed at 49
degrees relative to the airplane cabin bow-to-stern centerline in the
Boeing Model 737-10 airplane. The Boeing Model 737-10 airplane is a
twin-engine, transport-category airplane with seating for 230
passengers and a maximum takeoff weight of 197,900 pounds.
[[Page 8148]]
Type Certification Basis
Under the provisions of 14 CFR 21.101, Boeing must show that the
Model 737-10 airplane, as changed, continues 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 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, 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 Boeing Model 737-10 airplane must comply with the fuel-
vent and 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 Sec. 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 airplane will incorporate the following
novel or unusual design feature:
Single-occupant oblique seats, with airbag devices and 3-point
restraints, installed at 49 degrees relative to the airplane cabin bow-
to-stern centerline.
Discussion
Section 25.785(d) requires that each occupant of a seat installed
at an angle of more than 18 degrees, relative to bow-to-stern airplane
cabin centerline, must be protected from head injury using a seatbelt
and an energy-absorbing rest that supports the arms, shoulders, head,
and spine; or using a seatbelt and shoulder harness designed to prevent
the head from contacting any injurious object.
The Boeing Model 737-10 airplane single-occupant oblique seat
installation, with airbag devices and 3-point restraints, is novel such
that the current requirements do not adequately address airbag devices
and protection of the occupant's neck, spine, torso, and legs for
seating configurations that are positioned at an angle of 49 degrees
from the airplane centerline. The seating configuration installation
angle is beyond the installation-design limits of current special
conditions issued for seat positions at angles between 18 degrees and
45 degrees. For example, at these angles, lateral neck bending and
other injury mechanisms prevalent from a fully side-facing installation
become a concern. Although special conditions no. 25-552-SC was issued
for Boeing Model 787 airplane seats installed at 49 degrees in 2014,
that document is no longer applicable because they were issued prior to
the current oblique-seat special conditions that are based on the July
11, 2018, FAA policy statement PS-AIR-25-27, ``Technical Criteria for
Approving Oblique Seats.'' These special conditions are based on the
Boeing Model 787 airplane special conditions, with updates from that
policy statement, and to align with the fully side-facing-seat policy
statement PS-ANM-25-03-R1, ``Technical Criteria for Approving Side-
Facing Seats.''
To provide a level of safety equivalent to that afforded to
occupants of forward- and aft-facing seats, additional airworthiness
standards, in the form of dynamic testing requirements, including both
the injury criteria limits from the oblique-seat policy and the fully
side-facing-seat policy through new special conditions, are necessary.
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. 25-21-05-
SC for the Boeing Model 737-10 airplane, which was published in the
Federal Register on December 15, 2021 (86 FR 71183). The FAA received
one comment from the Air Line Pilots Association, International, in
support of the special conditions.
Applicability
As discussed above, these special conditions are applicable to the
Boeing Model 737-10 airplane. Should Boeing apply at a later date for a
change to the type certificate to include another model incorporating
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 of airplane. 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 Boeing Model 737-10 airplanes.
In addition to the requirements of Sec. Sec. 25.562 and 25.785,
passenger seats with airbag devices and 3-point restraints, installed
at an angle 49 degrees relative to the airplane cabin bow-to-stern
centerline, must meet the following:
a. Head Injury Criteria (HIC)
HIC assessments are required only for head contact with the seat
and other structure.
1. Compliance with Sec. 25.562(c)(5) is required, except that,
because an airbag device is present in addition to the 3-point
restraint system, when the anthropomorphic test dummy (ATD) has no
apparent contact with the seat and other structure but has contact with
the airbag, a HIC 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. ATD head contact with the seat or other structure through the
airbag, or contact subsequent to contact with the airbag, requires an
HIC value not exceeding 1000.
3. The HIC value must not exceed 1000 in any condition in which the
airbag does or does not deploy, up to the maximum severity pulse
specified by the existing requirements.
4. To accommodate a range of occupant heights (5th percentile
female to 95th percentile male), any surface, airbag or otherwise, that
provides support for the occupant head, must provide that support in a
consistent manner regardless of occupant stature. Otherwise, additional
HIC assessment tests may be needed.
[[Page 8149]]
b. Body-to-Wall/Furnishing Contact
If a seat is installed aft of structure, such as an interior wall
or furnishing 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 an occupant could contact. For example,
different yaw angles could result in different injury considerations
and airbag performance, and may require additional analysis, or
separate tests may be necessary to evaluate performance.
c. Neck Injury Criteria
1. 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.
2. Rotation of the head about its vertical axis, relative to the
torso, is limited to 105 degrees in either direction from forward-
facing.
3. The neck must not impact any surface that would produce
concentrated loading on the neck.
4. Assess neck injury for fore and aft neck bending using 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,'' applying
the following criteria: The Nij, calculated in accordance
with 49 CFR 571.208, must be below 1.0, where Nij =
Fz/Fzc + My/Myc, and
Nij critical values are:
Fzc = 1,530 lbs (6805 N) for tension
Fzc = 1,385 lbs (6160 N) for compression
Myc = 229 lb-ft (301 Nm) in flexion
Myc = 100 lb-ft (136 Nm) in extension
In addition, peak upper-neck Fz must be below 937 lbs
(4168 N) in tension and 899 lbs (3999 N) in compression.
5. When lateral neck bending is present, assess it using an ES-2re
ATD as defined by 49 CFR part 572, subpart U. The data must be filtered
at channel frequency class (CFC) 600 as defined in SAE Recommended
Practice J211-1, ``Instrumentation for Impact Test Part 1--Electrionic
Instrumentation:''
i. The upper-neck tension force at the occipital condyle (O.C.)
location must be less than 405 lbs (1,800 N).
ii. The upper-neck compression force at the O.C. location must be
less than 405 lbs (1,800 N).
iii. The upper-neck bending torque about the ATD x-axis at the O.C.
location must be less than 1,018 in-lbs (115 Nm).
iv. The upper-neck resultant shear force at the O.C. location must
be less than 186 lbs (825 N).
d. Spine and Torso Injury Criteria
1. The seating system must protect the occupant from experiencing
spine and torso injury. The assessment of spine and torso injury must
be conducted with the airbag device activated, unless it is necessary
to also consider that the occupant-injury potential would be higher for
impacts below the airbag-device deployment threshold.
2. Assess spine and torso injury, for oblique torso bending, using
the FAA Hybrid III ATD, applying the following criteria:
i. The lumbar spine tension (Fz) cannot exceed 1,200 lbs
(5338 N).
ii. 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 Recommended Practice J211-1.
3. When lateral torso bending is present, assess spine and torso
injury using an ES-2re ATD, applying the following criteria:
i. Thoracic: The deflection of any of the ES-2re ATD upper, middle,
and lower ribs must not exceed 1.73 inches (44 mm). Process the data as
defined in Federal Motor Vehicle Safety Standards (FMVSS) 571.214,
title 49 of the CFR.
ii. Abdominal: The sum of the measured ES-2re ATD front, middle,
and rear abdominal forces must not exceed 562 lbs (2,500 N). Process
the data as defined in FMVSS 571.214.
iii. Upper-torso support: The lateral flexion of the ATD torso must
not exceed 40 degrees from the normal upright positions during impact.
e. Pelvic Criteria
1. The seating system must protect the occupant from experiencing
pelvis injury.
2. Any part of the load-bearing portion of the bottom of the ATD
pelvis must not translate beyond the edges of the seat bottom seat-
cushion supporting structure.
3. When pelvis contact with the armrest or surrounding interior
components is present, assess it using an ES-2re ATD. The pubic
symphysis force measured by the ES-2re ATD must not exceed 1,350 lbs
(6,000 N). Process the data as defined in FMVSS 571.214.
f. Femur Criteria
Limit axial rotations of the upper leg (about the z-axis of the
femur, per SAE Recommended Practice J211-1) to 35 degrees from the
nominal seated position. Evaluation during rebound does not need to be
considered.
g. ATD and Test Condition
1. Perform longitudinal tests, conducted to measure the injury
criteria above, using the FAA Hybrid III ATD or using the ES-2re ATD.
Conduct the tests with the undeformed floor, at the most-critical yaw
cases for injury, and with all lateral structural supports (e.g.,
armrests or walls) installed.
2. For longitudinal tests 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, to ensure
proper loading of the seat by the occupant, the ATD pelvis must remain
supported by the seat pan, and the restraint system must remain on the
pelvis of the ATD until rebound begins. No injury criteria evaluation
is necessary for tests conducted only to assess seat-strength
requirements.
3. If a seat installation includes adjacent items that are within
contact range of an occupant, assess the injury potential of that
contact. To make this assessment, tests may be conducted to include the
actual contact item, located and attached in a representative fashion.
Alternatively, the injury potential may be assessed through a
combination of tests with contact items having the same geometry as the
actual contact item, but having stiffness characteristics that would
create the worst case for injury, such as injuries due to both contact
with the item and lack of support from the item.
4. Conduct the combined horizontal and vertical test, required by
Sec. 25.562(b)(1) and these special conditions, with the FAA Hybrid II
ATD (49 CFR part 572, subpart B, as specified in Sec. 25.562) or
equivalent.
5. The design and installation of seatbelt buckles must prevent
unbuckling due to applied inertial forces, or impact from seat occupant
hands and arms, during an emergency landing.
h. Inflatable Airbag-Restraint System Special Conditions
An inflatable airbag-restraint system will be installed, and must
meet the requirements of Special Conditions No. 25-386-SC, ``Boeing
Model 737-600/-700/-700C/-800/-900 and 900ER Series
[[Page 8150]]
Airplanes; Seats With Inflatable Lapbelts,'' applicable to Boeing Model
737-10 series airplanes.
i. General Test Guidelines
1. The determination of the appropriate ATD to be used in assessing
occupant injury (FAA Hybrid III or ES-2re) is based on the occupant
kinematics at the selected test angle. At the +10-degree yaw angle, the
occupant kinematics show that occupant injury tests, using both ATDs,
are required.
2. Conduct vertical tests with the Hybrid II ATD or equivalent,
with existing pass/fail criteria.
3. Conduct longitudinal structural tests with the Hybrid II ATD or
equivalent, deformed floor, with 10 degrees yaw, and with all lateral
structural supports (e.g., armrests or walls) required to support the
occupant.
4. Conduct longitudinal occupant-injury tests, as necessary, with
the FAA Hybrid III ATD or ES-2re ATD, undeformed floor, yaw, and with
all lateral structural supports (e.g., armrests or walls) critically
represented, and which are within contact range of the occupant.
i. Pass/fail injury assessments:
A. Perform HIC, fore and aft neck injury, spinal tension, and femur
evaluations using the FAA Hybrid III ATD.
B. Perform lateral neck injury, thoracic, abdominal, pelvis, and
femur evaluations using the ES-2re ATD.
5. For injury assessments accomplished by testing with the ES-2re
ATD for longitudinal tests 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:
i. 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). Install
the modules such that the moving end of the rib module is toward the
front of the airplane. Install the three abdominal-force sensors such
that they are on the side of the ATD toward the front of the airplane.
ii. ATD Clothing:
Clothe each ATD in form-fitting cotton-stretch garments with short-
to full-length sleeves, mid-calf to full-length pants, and size 11E
(45) shoes weighing about 2.5 lbs (1.1 kg), and having a heel height of
about 1.5 inches (3.8 cm). The color of the clothing should be in
contrast to the color of the restraint system and the background. The
color of the clothing should be chosen to avoid overexposing the high-
speed images captured during the test. The ES-2re jacket is sufficient
for torso clothing, although a form-fitting shirt may be used in
addition, if desired.
iii. ATD Positioning:
A. Lower the ATD vertically into the seat while simultaneously:
(1) Aligning the midsagittal plane (a vertical plane through the
midline of the body, dividing the body into right and left halves) to
approximately the middle of the seat place.
(2) Keeping the upper legs horizontal by supporting them just
behind the knees.
(3) Applying a horizontal x-axis direction (in the ES-2re ATD
coordinate system) force of about 20 lbs (89 N) to the bottom rib of
the ES-2re, to compress the seat-back cushion.
B. After all lifting devices have been removed from the ATD:
(1) Rock it slightly to settle it in the seat.
(2) Bend the knees of the ATD.
(3) Separate the knees by about 4 inches (100 mm).
(4) Set the ATD's head at approximately the midpoint of the
available range of z-axis rotation (to align the head and torso
midsagittal planes).
(5) Position the ATD's arms at the joints' mechanical detent, to
position them to an approximately 20- to 40-degree angle with respect
to the torso.
(6) Position the feet such that the centerlines of the lower legs
are approximately parallel.
Note: Seats installed via plinths or pallets must meet 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.
Issued in Kansas City, Missouri, on February 8, 2022.
Patrick R. Mullen,
Manager, Technical Innovation Policy Branch, Policy and Innovation
Division, Aircraft Certification Service.
[FR Doc. 2022-03012 Filed 2-11-22; 8:45 am]
BILLING CODE 4910-13-P
