Special Conditions: The Boeing Company Model 787-10 Series Airplanes; Dynamic Test Requirements for Single-Occupant Oblique Seats With Pretensioner Restraint Systems, 41334-41337 [2020-13760]
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41334
Federal Register / Vol. 85, No. 133 / Friday, July 10, 2020 / Rules and Regulations
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.
7. Head Injury Criteria (HIC):
The HIC value must not exceed 1000
at any condition at which the
pretensioner does or does not deploy,
up to the maximum severity pulse that
corresponds to the test conditions
specified in § 25.562. Tests must be
performed to demonstrate this, taking
into account any necessary tolerances
for deployment.
When an airbag device is present in
addition to the pretensioner restraint
system, and the anthropormorphic test
device (ATD) has no apparent contact
with the seat/structure but has contact
with an airbag, a HIC unlimited scored
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. ATD head
contact with the seat or other structure,
through the airbag, or contact
subsequent to contact with the airbag,
requires a HIC value that does not
exceed 1000.
8. Protection During Secondary
Impacts:
The pretensioner activation setting
must be demonstrated to maximize the
probability of the protection being
available when needed, considering
secondary impacts.
9. Protection of Occupants Other than
50th Percentile:
Protection of occupants for a range of
stature from a 2-year-old child to a 95th
percentile male must be shown. For
shoulder harnesses that include
pretensioners, protection of occupants
other than a 50th percentile male may
be shown by test or analysis. In
addition, the pretensioner must not
introduce a hazard to passengers due to
the following seating configurations:
a. The seat occupant is holding an
infant.
b. The seat occupant is a child in a
child-restraint device.
c. The seat occupant is a pregnant
woman.
10. Occupants Adopting the Brace
Position:
Occupants in the traditional brace
position when the pretensioner activates
must not experience adverse effects
from the pretensioner activation.
11. Inadvertent Pretensioner
Actuation:
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a. The probability of inadvertent
pretensioner actuation must be shown
to be extremely remote (i.e., average
probability per flight hour of less than
10¥7).
b. The system must be shown not
susceptible to inadvertent pretensioner
actuation as a result of wear and tear, or
inertia loads resulting from in-flight or
ground maneuvers likely to be
experienced in service.
c. The seated occupant must not be
seriously injured as a result of
inadvertent pretensioner actuation.
d. Inadvertent pretensioner activation
must not cause a hazard to the airplane,
nor cause serious injury to anyone who
may be positioned close to the retractor
or belt (e.g., seated in an adjacent seat
or standing adjacent to the seat).
12. Availability of the Pretensioner
Function Prior to Flight:
The design must provide means for a
crewmember to verify the availability of
the pretensioner function prior to each
flight, or the probability of failure of the
pretensioner function must be
demonstrated to be extremely remote
(i.e., average probability per flight hour
of less than 10¥7) between inspection
intervals.
13. Incorrect Seat Belt Orientation:
The system design must ensure that
any incorrect orientation (twisting) of
the seat belt does not compromise the
pretensioner protection function.
14. Contamination Protection:
The pretensioner mechanisms and
controls must be protected from external
contamination associated with that
which could occur on or around
passenger seating.
15. Prevention of Hazards:
The pretensioner system must not
induce a hazard to passengers in case of
fire, nor create a fire hazard, if activated.
16. Functionality After Loss of Power:
The system must function properly
after loss of normal airplane electrical
power, and after a transverse separation
in the fuselage at the most critical
location. A separation at the location of
the system does not have to be
considered.
Issued in Des Moines, Washington, on June
22, 2020.
James E. Wilborn,
Acting Manager, Transport Standards
Branch, Policy and Innovation Division,
Aircraft Certification Service.
[FR Doc. 2020–13759 Filed 7–9–20; 8:45 am]
BILLING CODE 4910–13–P
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA–2019–0841; Special
Conditions No. 25–770–SC]
Special Conditions: The Boeing
Company Model 787–10 Series
Airplanes; Dynamic Test Requirements
for Single-Occupant Oblique Seats
With Pretensioner Restraint Systems
Federal Aviation
Administration (FAA), Transportation
(DOT).
AGENCY:
ACTION:
Final special conditions.
These special conditions are
issued for The Boeing Company
(Boeing) Model 787–10 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 single-occupant oblique seats
equipped with pretensioner restraint
systems. 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.
SUMMARY:
DATES:
Effective August 10, 2020.
FOR FURTHER INFORMATION CONTACT:
Shannon Lennon, Airframe and Cabin
Safety Section, AIR–675, Transport
Standards Branch, Policy and
Innovation Division, Aircraft
Certification Service, Federal Aviation
Administration, 2200 South 216th
Street, Des Moines, Washington 98198;
telephone and fax 206–231–3209; email
shannon.lennon@faa.gov.
SUPPLEMENTARY INFORMATION:
Background
On July 18, 2018, Boeing applied for
a change to Type Certificate No.
T00021SE for single-occupant oblique
seats with pretensioner restraint
systems, instead of airbags, which are
the typical restraints used to protect the
passengers from head injuries. These
seats are to be installed in Boeing Model
787–10 series airplanes. The Boeing
Model 787–10 series airplanes are twinengine, transport-category airplanes
with passenger seating capacity of 440
and a maximum takeoff weight of
560,000 pounds.
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Federal Register / Vol. 85, No. 133 / Friday, July 10, 2020 / Rules and Regulations
Type Certification Basis
Under the provisions of title 14, Code
of Federal Regulations (14 CFR) 21.101,
Boeing must show that the Model 787–
10 series airplanes, as changed,
continue to meet the applicable
provisions of the regulations listed in
Type Certificate No. T00021SE 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 Boeing Model 787–10 series
airplanes 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, Boeing Model 787–10 series
airplanes must comply with the fuelvent 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 14 CFR 11.19, in accordance
with § 11.38, and they become part of
the type certification basis under
§ 21.101.
Novel or Unusual Design Features
The Boeing Model 787–10 series
airplanes will incorporate the following
novel or unusual design feature:
Single-occupant oblique seats with
pretensioner restraint systems to protect
the passengers from head injuries.
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Discussion
Boeing will install, in Model 787–10
series airplanes, oblique (side-facing)
seats that incorporate seatbelts with a
pretensioner system at each seat place,
to comply with the occupant injury
criteria of § 25.562(c)(5).
The FAA has been conducting and
sponsoring research on appropriate
injury criteria for oblique seat
installations. However, the FAA
research program is not complete, and
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the FAA may update these criteria as
further research results are collected. To
reflect current research findings, the
FAA issued policy statements PS–
ANM–25–03–R1, ‘‘Technical Criteria for
Approving Side-Facing Seats,’’
November 12, 2012, which updates
injury criteria for fully side-facing seats,
and PS–AIR–25–27, ‘‘Technical Criteria
for Approving Oblique Seats,’’ July 11,
2018, to define injury criteria for
oblique seats. These policies provide
background and technical information
as well as applicable injury criteria.
The installation of obliquely oriented
passenger seats are novel such that the
current certification basis does not
adequately address occupant-protection
expectations with regard to the
occupant’s neck and spine for seat
configurations that are positioned at an
angle greater than 18 degrees from the
airplane longitudinal centerline.
The installation of passenger seats at
angles between 18 and 45 degrees from
the airplane longitudinal centerline are
unusual due to the seat occupant
interface with the surrounding
furniture, and which introduce
occupant alignment and loading
concerns with or without the
installation of 3-point or airbag-restraint
systems.
FAA-sponsored research has found
that an unrestrained 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 the FAA Hybrid III
anthropomorphic test device (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 spinal-tension limit
selected is conservative with respect to
other aviation injury criteria because it
corresponds to a no-injury loading
condition, but the degree of
conservatism is unknown because the
precise spinal-loading level at which
injuries would begin to occur is
unknown. The small number of humansubject tests accomplished during this
research project limits the robustness of
the selected tension limit.
Other restraint systems have been
used to comply with the occupant
injury criteria of § 25.562(c)(5). For
instance, shoulder harnesses have been
widely used on flight attendant seats,
flight-deck seats, in business jets, and in
general-aviation airplanes to reduce
occupant head injury in the event of an
emergency landing. Special conditions,
pertinent regulations, and published
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41335
guidance exist that relate to other
restraint systems. However, the use of
pretensioners in the restraint system on
transport-airplane seats is a novel
design.
Pretensioner technology involves a
step-change in loading experienced by
the occupant for impacts below and
above that at which the device deploys,
because activation of the shoulder
harness, at the point at which the
pretensioner engages, interrupts uppertorso excursion. This could result in the
head injury criteria (HIC) being higher at
an intermediate impact condition than
that resulting from the maximum impact
condition corresponding to the test
conditions specified in § 25.562. See
condition 7 in these special conditions.
The ideal triangular maximumseverity pulse is defined in Advisory
Circular (AC) 25.562–1B. For the
evaluation and testing of less-severe
pulses for purposes of assessing the
effectiveness of the pretensioner setting,
a similar triangular pulse should be
used with acceleration, rise time, and
velocity change scaled accordingly. The
magnitude of the required pulse should
not deviate below the ideal pulse by
more than 0.5g until 1.33 t1 is reached,
where t1 represents the time interval
between 0 and t1 on the referenced
pulse shape as shown in AC 25.562–1B.
This is an acceptable method of
compliance to the test requirements of
the special conditions.
Additionally, the pretensioner might
not provide protection, after actuation,
during secondary impacts. Therefore,
the case where a small impact is
followed by a large impact should be
addressed. If the minimum deceleration
severity at which the pretensioner is set
to deploy is unnecessarily low, the
protection offered by the pretensioner
may be lost by the time a second larger
impact occurs.
The existing special conditions for
Model 787 oblique seat installations do
not adequately address oblique seats
with 3-point and pretensioner restraint
systems. Therefore, the proposed
configuration requires special
conditions.
Conditions 1 through 6 address
occupant protection in consideration of
the oblique-facing seats. Conditions 7
through 10 ensure that the pretensioner
system activates when intended, to
provide the necessary protection of
occupants. This includes protection of a
range of occupants under various
accident conditions. Conditions 11
through 16 address maintenance and
reliability of the pretensioner system,
including any outside influences on the
mechanism, to ensure it functions as
intended.
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Federal Register / Vol. 85, No. 133 / Friday, July 10, 2020 / Rules and Regulations
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.
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Discussion of Comments
The FAA issued Notice of Proposed
Special Conditions No. 25–20–02–SC
for the Boeing Model 787–10 series
airplane, which was published in the
Federal Register on March 2, 2020 (85
FR 12230). The FAA received responses
from three commenters.
Boeing suggested one edit for clarity,
to the paragraph immediately preceding
the list of conditions in the Special
Conditions section, to change text that
reads, ‘‘. . . passenger seats installed at
an angle 18 degrees and 45 degrees
. . .’’ to read, ‘‘. . . passenger seats
installed at an angle between 18 degrees
and 45 degrees . . .’’ The FAA concurs
with the suggested change because the
change more correctly conveys the
installation angle range for oblique seats
discussed in these special conditions.
Boeing recommended adding two
sentences at the end of condition no. 7
regarding HIC, to be consistent with
same-topic special conditions
previously issued. It is the FAA’s
understanding that the proposed
pretensioner restraint system is
intended to replace the use of an airbag
system as mentioned in the Background
section of this document. Therefore, the
information Boeing requested,
pertaining to HIC associated with airbag
contact, would not apply to these
special conditions as originally
proposed. However, in the event that an
airbag device is incorporated in
conjunction with a pretensioner
restraint system, the FAA agrees to
include the additional information
consistent with the information
provided in recently published obliqueseat special conditions. When present,
the airbag device (e.g., inflatable lap-belt
airbag or structure-mounted airbag)
must also meet the existing special
conditions applicable to either inflatable
lap belts or structure-mounted airbags.
An individual commenter states,
‘‘Diagrams of the proposed seat
installation with and without a person
sitting in it would provide the visual
context to the proposed regulation.
Also, a seat diagram would help clarify
how neck injuries will be mitigated by
the restraint system is vague. Assuming
a crash, would a person’s neck just
receive minor injuries resulting in
whiplash [or] is the seat designed to
reduce head movement during
crashes?’’
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The pretensioner restraint system,
which is incorporated into the seat
design, is intended to eliminate slack in
the shoulder harness, and to pull the
occupant back into the seat prior to
impact. This has the effect of reducing
occupant forward translation and
reducing head movement, thus
minimizing the potential for injuries.
Based on this description of the
pretensioner restraint system, the FAA
has determined that it is not necessary
to provide a seat diagram to convey the
same information. Further discussion
regarding the development of criteria to
address occupant injuries can be found
in FAA Policy Statement PS–AIR–25–
27, Appendix A.
Another individual commenter asks,
‘‘Has an investigation been completed as
to how much aircraft evacuations may
be affected by canting the seats at an
angle from centerline?’’
An investigation of the effects of
obliquely positioned (canted) seat
installations on aircraft evacuations has
not been conducted because it is not
necessary to do so. Occupants in
oblique seats have access to egress aisles
as well as visibility of emergency exits
and exit signs similar to occupants of
non-oblique, forward-facing seats.
Furthermore, for all interior
configuration variants, it is the
installer’s responsibility to demonstrate
evacuation capability of the airplane,
via demonstration of compliance to
§ 25.803, prior to certification.
Except as discussed above, the special
conditions are adopted as proposed.
Applicability
As discussed above, these special
conditions are applicable to Boeing
Model 787–10 series airplanes. 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 series of airplanes. It is not a rule
of general applicability.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting
and recordkeeping requirements.
Authority Citation
The authority citation for these
special conditions is as follows:
Authority: 49 U.S.C. 106(f), 106(g), 40113,
44701, 44702, 44704.
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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
787–10 series airplanes.
In addition to the requirements of
§ 25.562, passenger seats installed at an
angle between 18 degrees and 45
degrees from the airplane longitudinal
centerline must meet the following:
1. Body-to-Wall and Body-toFurnishing Contact:
If a seat is installed aft of structure,
such as an interior wall or furnishings,
and which 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 which an occupant could contact.
For example if, in addition to a
pretensioner restraint system, an airbag
device is present, different yaw angles
could result in different airbag-device
performance, then additional analysis or
separate tests may be necessary to
evaluate performance.
2. Neck Injury Criteria:
a. The seating system must protect the
occupant from experiencing serious
neck injury. In addition to a
pretensioner restraint system, if an
airbag device also is present, 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.
b. 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 = 1530 lbs for tension
Fzc = 1385 lbs for compression
Myc = 229 lb-ft in flexion
Myc = 100 lb-ft in extension
c. Peak Fz must be below 937 lbs in
tension and 899 lbs in compression.
d. Rotation of the head about its
vertical axis relative to the torso is
limited to 105 degrees in either
direction from forward facing.
e. The neck must not impact any
surface that would produce
concentrated loading on the neck.
3. Spine and Torso Injury Criteria:
a. The lumbar spine tension (Fz)
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
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Federal Register / Vol. 85, No. 133 / Friday, July 10, 2020 / Rules and Regulations
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, ‘‘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.
4. Pelvis Criteria:
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.
5. 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.
6. 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. 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.
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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.
7. Head Injury Criteria (HIC):
The HIC value must not exceed 1000
at any condition at which the
pretensioner does or does not deploy,
up to the maximum severity pulse that
corresponds to the test conditions
specified in § 25.562. Tests must be
performed to demonstrate this, taking
into account any necessary tolerances
for deployment.
When an airbag device is present in
addition to the pretensioner restraint
system, and the anthropormorphic test
device (ATD) has no apparent contact
with the seat/structure but has contact
with an airbag, a HIC unlimited scored
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. ATD head
contact with the seat or other structure,
through the airbag, or contact
subsequent to contact with the airbag,
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requires a HIC value that does not
exceed 1000.
8. Protection During Secondary
Impacts:
The pretensioner activation setting
must be demonstrated to maximize the
probability of the protection being
available when needed, considering
secondary impacts.
9. Protection of Occupants Other than
50th Percentile:
Protection of occupants for a range of
stature from a 2-year-old child to a 95th
percentile male must be shown. For
shoulder harnesses that include
pretensioners, protection of occupants
other than a 50th percentile male may
be shown by test or analysis. In
addition, the pretensioner must not
introduce a hazard to passengers due to
the following seating configurations:
a. The seat occupant is holding an
infant.
b. The seat occupant is a child in a
child-restraint device.
c. The seat occupant is a pregnant
woman.
10. Occupants Adopting the Brace
Position:
Occupants in the traditional brace
position when the pretensioner activates
must not experience adverse effects
from the pretensioner activation.
11. Inadvertent Pretensioner
Actuation:
a. The probability of inadvertent
pretensioner actuation must be shown
to be extremely remote (i.e., average
probability per flight hour of less than
10¥7).
b. The system must be shown not
susceptible to inadvertent pretensioner
actuation as a result of wear and tear, or
inertia loads resulting from in-flight or
ground maneuvers likely to be
experienced in service.
c. The seated occupant must not be
seriously injured as a result of
inadvertent pretensioner actuation.
d. Inadvertent pretensioner activation
must not cause a hazard to the airplane,
nor cause serious injury to anyone who
may be positioned close to the retractor
or belt (e.g., seated in an adjacent seat
or standing adjacent to the seat).
12. Availability of the Pretensioner
Function Prior to Flight:
The design must provide means for a
crewmember to verify the availability of
the pretensioner function prior to each
flight, or the probability of failure of the
pretensioner function must be
demonstrated to be extremely remote
(i.e., average probability per flight hour
of less than 10¥7) between inspection
intervals.
13. Incorrect Seat Belt Orientation:
The system design must ensure that
any incorrect orientation (twisting) of
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41337
the seat belt does not compromise the
pretensioner protection function.
14. Contamination Protection:
The pretensioner mechanisms and
controls must be protected from external
contamination associated with that
which could occur on or around
passenger seating.
15. Prevention of Hazards:
The pretensioner system must not
induce a hazard to passengers in case of
fire, nor create a fire hazard, if activated.
16. Functionality After Loss of Power:
The system must function properly
after loss of normal airplane electrical
power, and after a transverse separation
in the fuselage at the most critical
location. A separation at the location of
the system does not have to be
considered.
Issued in Des Moines, Washington, on June
22, 2020.
James E. Wilborn,
Acting Manager, Transport Standards
Branch, Policy and Innovation Division,
Aircraft Certification Service.
[FR Doc. 2020–13760 Filed 7–9–20; 8:45 am]
BILLING CODE 4910–13–P
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 71
[Docket No. FAA–2020–0361; Airspace
Docket No. 20–AEA–9]
RIN 2120–AA66
Amendment of the Class D and Class
E Airspace and Revocation of Class E
Airspace; Erie and Corry, PA
Federal Aviation
Administration (FAA), DOT.
ACTION: Final rule.
AGENCY:
This action amends the Class
D airspace, Class E surface area airspace,
and Class E airspace extending upward
from 700 feet above the surface at Erie
International Airport/Tom Ridge Field,
Erie, PA; revokes the Class E airspace
area designated as an extension to Class
D and Class E surface area at Erie
International Airport/Tom Ridge Field;
and amends the Class E airspace
extending upward from 700 feet above
the surface at Corry-Lawrence Airport,
Corry, PA. This action is the result of
airspace reviews due to the
decommissioning of the Tidioute VHF
omnidirectional range (VOR) navigation
aid as part of the VOR Minimum
Operational Network (MON) Program.
DATES: Effective 0901 UTC, September
10, 2020. The Director of the Federal
Register approves this incorporation by
SUMMARY:
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]]>Agencies
[Federal Register Volume 85, Number 133 (Friday, July 10, 2020)]
[Rules and Regulations]
[Pages 41334-41337]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-13760]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2019-0841; Special Conditions No. 25-770-SC]
Special Conditions: The Boeing Company Model 787-10 Series
Airplanes; Dynamic Test Requirements for Single-Occupant Oblique Seats
With Pretensioner Restraint Systems
AGENCY: Federal Aviation Administration (FAA), Transportation (DOT).
ACTION: Final special conditions.
-----------------------------------------------------------------------
SUMMARY: These special conditions are issued for The Boeing Company
(Boeing) Model 787-10 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 single-occupant oblique
seats equipped with pretensioner restraint systems. 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 August 10, 2020.
FOR FURTHER INFORMATION CONTACT: Shannon Lennon, Airframe and Cabin
Safety Section, AIR-675, Transport Standards Branch, Policy and
Innovation Division, Aircraft Certification Service, Federal Aviation
Administration, 2200 South 216th Street, Des Moines, Washington 98198;
telephone and fax 206-231-3209; email [email protected].
SUPPLEMENTARY INFORMATION:
Background
On July 18, 2018, Boeing applied for a change to Type Certificate
No. T00021SE for single-occupant oblique seats with pretensioner
restraint systems, instead of airbags, which are the typical restraints
used to protect the passengers from head injuries. These seats are to
be installed in Boeing Model 787-10 series airplanes. The Boeing Model
787-10 series airplanes are twin-engine, transport-category airplanes
with passenger seating capacity of 440 and a maximum takeoff weight of
560,000 pounds.
[[Page 41335]]
Type Certification Basis
Under the provisions of title 14, Code of Federal Regulations (14
CFR) 21.101, Boeing must show that the Model 787-10 series airplanes,
as changed, continue to meet the applicable provisions of the
regulations listed in Type Certificate No. T00021SE 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 Boeing Model 787-10 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, Boeing Model 787-10 series airplanes 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 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 787-10 series airplanes will incorporate the
following novel or unusual design feature:
Single-occupant oblique seats with pretensioner restraint systems
to protect the passengers from head injuries.
Discussion
Boeing will install, in Model 787-10 series airplanes, oblique
(side-facing) seats that incorporate seatbelts with a pretensioner
system at each seat place, to comply with the occupant injury criteria
of Sec. 25.562(c)(5).
The FAA has been conducting and sponsoring research on appropriate
injury criteria for oblique seat installations. However, the FAA
research program is not complete, and the FAA may update these criteria
as further research results are collected. To reflect current research
findings, the FAA issued policy statements PS-ANM-25-03-R1, ``Technical
Criteria for Approving Side-Facing Seats,'' November 12, 2012, which
updates injury criteria for fully side-facing seats, and PS-AIR-25-27,
``Technical Criteria for Approving Oblique Seats,'' July 11, 2018, to
define injury criteria for oblique seats. These policies provide
background and technical information as well as applicable injury
criteria.
The installation of obliquely oriented passenger seats are novel
such that the current certification basis does not adequately address
occupant-protection expectations with regard to the occupant's neck and
spine for seat configurations that are positioned at an angle greater
than 18 degrees from the airplane longitudinal centerline.
The installation of passenger seats at angles between 18 and 45
degrees from the airplane longitudinal centerline are unusual due to
the seat occupant interface with the surrounding furniture, and which
introduce occupant alignment and loading concerns with or without the
installation of 3-point or airbag-restraint systems.
FAA-sponsored research has found that an unrestrained 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 the FAA Hybrid III anthropomorphic
test device (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 spinal-tension
limit selected is conservative with respect to other aviation injury
criteria because it corresponds to a no-injury loading condition, but
the degree of conservatism is unknown because the precise spinal-
loading level at which injuries would begin to occur is unknown. The
small number of human-subject tests accomplished during this research
project limits the robustness of the selected tension limit.
Other restraint systems have been used to comply with the occupant
injury criteria of Sec. 25.562(c)(5). For instance, shoulder harnesses
have been widely used on flight attendant seats, flight-deck seats, in
business jets, and in general-aviation airplanes to reduce occupant
head injury in the event of an emergency landing. Special conditions,
pertinent regulations, and published guidance exist that relate to
other restraint systems. However, the use of pretensioners in the
restraint system on transport-airplane seats is a novel design.
Pretensioner technology involves a step-change in loading
experienced by the occupant for impacts below and above that at which
the device deploys, because activation of the shoulder harness, at the
point at which the pretensioner engages, interrupts upper-torso
excursion. This could result in the head injury criteria (HIC) being
higher at an intermediate impact condition than that resulting from the
maximum impact condition corresponding to the test conditions specified
in Sec. 25.562. See condition 7 in these special conditions.
The ideal triangular maximum-severity pulse is defined in Advisory
Circular (AC) 25.562-1B. For the evaluation and testing of less-severe
pulses for purposes of assessing the effectiveness of the pretensioner
setting, a similar triangular pulse should be used with acceleration,
rise time, and velocity change scaled accordingly. The magnitude of the
required pulse should not deviate below the ideal pulse by more than
0.5g until 1.33 t1 is reached, where t1
represents the time interval between 0 and t1 on the
referenced pulse shape as shown in AC 25.562-1B. This is an acceptable
method of compliance to the test requirements of the special
conditions.
Additionally, the pretensioner might not provide protection, after
actuation, during secondary impacts. Therefore, the case where a small
impact is followed by a large impact should be addressed. If the
minimum deceleration severity at which the pretensioner is set to
deploy is unnecessarily low, the protection offered by the pretensioner
may be lost by the time a second larger impact occurs.
The existing special conditions for Model 787 oblique seat
installations do not adequately address oblique seats with 3-point and
pretensioner restraint systems. Therefore, the proposed configuration
requires special conditions.
Conditions 1 through 6 address occupant protection in consideration
of the oblique-facing seats. Conditions 7 through 10 ensure that the
pretensioner system activates when intended, to provide the necessary
protection of occupants. This includes protection of a range of
occupants under various accident conditions. Conditions 11 through 16
address maintenance and reliability of the pretensioner system,
including any outside influences on the mechanism, to ensure it
functions as intended.
[[Page 41336]]
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. 25-20-02-
SC for the Boeing Model 787-10 series airplane, which was published in
the Federal Register on March 2, 2020 (85 FR 12230). The FAA received
responses from three commenters.
Boeing suggested one edit for clarity, to the paragraph immediately
preceding the list of conditions in the Special Conditions section, to
change text that reads, ``. . . passenger seats installed at an angle
18 degrees and 45 degrees . . .'' to read, ``. . . passenger seats
installed at an angle between 18 degrees and 45 degrees . . .'' The FAA
concurs with the suggested change because the change more correctly
conveys the installation angle range for oblique seats discussed in
these special conditions.
Boeing recommended adding two sentences at the end of condition no.
7 regarding HIC, to be consistent with same-topic special conditions
previously issued. It is the FAA's understanding that the proposed
pretensioner restraint system is intended to replace the use of an
airbag system as mentioned in the Background section of this document.
Therefore, the information Boeing requested, pertaining to HIC
associated with airbag contact, would not apply to these special
conditions as originally proposed. However, in the event that an airbag
device is incorporated in conjunction with a pretensioner restraint
system, the FAA agrees to include the additional information consistent
with the information provided in recently published oblique-seat
special conditions. When present, the airbag device (e.g., inflatable
lap-belt airbag or structure-mounted airbag) must also meet the
existing special conditions applicable to either inflatable lap belts
or structure-mounted airbags.
An individual commenter states, ``Diagrams of the proposed seat
installation with and without a person sitting in it would provide the
visual context to the proposed regulation. Also, a seat diagram would
help clarify how neck injuries will be mitigated by the restraint
system is vague. Assuming a crash, would a person's neck just receive
minor injuries resulting in whiplash [or] is the seat designed to
reduce head movement during crashes?''
The pretensioner restraint system, which is incorporated into the
seat design, is intended to eliminate slack in the shoulder harness,
and to pull the occupant back into the seat prior to impact. This has
the effect of reducing occupant forward translation and reducing head
movement, thus minimizing the potential for injuries. Based on this
description of the pretensioner restraint system, the FAA has
determined that it is not necessary to provide a seat diagram to convey
the same information. Further discussion regarding the development of
criteria to address occupant injuries can be found in FAA Policy
Statement PS-AIR-25-27, Appendix A.
Another individual commenter asks, ``Has an investigation been
completed as to how much aircraft evacuations may be affected by
canting the seats at an angle from centerline?''
An investigation of the effects of obliquely positioned (canted)
seat installations on aircraft evacuations has not been conducted
because it is not necessary to do so. Occupants in oblique seats have
access to egress aisles as well as visibility of emergency exits and
exit signs similar to occupants of non-oblique, forward-facing seats.
Furthermore, for all interior configuration variants, it is the
installer's responsibility to demonstrate evacuation capability of the
airplane, via demonstration of compliance to Sec. 25.803, prior to
certification.
Except as discussed above, the special conditions are adopted as
proposed.
Applicability
As discussed above, these special conditions are applicable to
Boeing Model 787-10 series airplanes. 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 series of airplanes. It is not a rule of general
applicability.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
Authority Citation
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701, 44702,
44704.
The Special Conditions
Accordingly, pursuant to the authority delegated to me by the
Administrator, the following special conditions are issued as part of
the type certification basis for Boeing Model 787-10 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
airplane longitudinal centerline must meet the following:
1. Body-to-Wall and Body-to-Furnishing Contact:
If a seat is installed aft of structure, such as an interior wall
or furnishings, and which 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 which an occupant could contact. For
example if, in addition to a pretensioner restraint system, an airbag
device is present, different yaw angles could result in different
airbag-device performance, then additional analysis or separate tests
may be necessary to evaluate performance.
2. Neck Injury Criteria:
a. The seating system must protect the occupant from experiencing
serious neck injury. In addition to a pretensioner restraint system, if
an airbag device also is present, 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.
b. 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 = 1530 lbs for tension
Fzc = 1385 lbs for compression
Myc = 229 lb-ft in flexion
Myc = 100 lb-ft in extension
c. Peak Fz must be below 937 lbs in tension and 899 lbs
in compression.
d. Rotation of the head about its vertical axis relative to the
torso is limited to 105 degrees in either direction from forward
facing.
e. The neck must not impact any surface that would produce
concentrated loading on the neck.
3. Spine and Torso Injury Criteria:
a. The lumbar spine tension (Fz) 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
[[Page 41337]]
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, ``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.
4. Pelvis Criteria:
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.
5. 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.
6. 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. 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.
7. Head Injury Criteria (HIC):
The HIC value must not exceed 1000 at any condition at which the
pretensioner does or does not deploy, up to the maximum severity pulse
that corresponds to the test conditions specified in Sec. 25.562.
Tests must be performed to demonstrate this, taking into account any
necessary tolerances for deployment.
When an airbag device is present in addition to the pretensioner
restraint system, and the anthropormorphic test device (ATD) has no
apparent contact with the seat/structure but has contact with an
airbag, a HIC unlimited scored 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. ATD head contact with the seat or
other structure, through the airbag, or contact subsequent to contact
with the airbag, requires a HIC value that does not exceed 1000.
8. Protection During Secondary Impacts:
The pretensioner activation setting must be demonstrated to
maximize the probability of the protection being available when needed,
considering secondary impacts.
9. Protection of Occupants Other than 50th Percentile:
Protection of occupants for a range of stature from a 2-year-old
child to a 95th percentile male must be shown. For shoulder harnesses
that include pretensioners, protection of occupants other than a 50th
percentile male may be shown by test or analysis. In addition, the
pretensioner must not introduce a hazard to passengers due to the
following seating configurations:
a. The seat occupant is holding an infant.
b. The seat occupant is a child in a child-restraint device.
c. The seat occupant is a pregnant woman.
10. Occupants Adopting the Brace Position:
Occupants in the traditional brace position when the pretensioner
activates must not experience adverse effects from the pretensioner
activation.
11. Inadvertent Pretensioner Actuation:
a. The probability of inadvertent pretensioner actuation must be
shown to be extremely remote (i.e., average probability per flight hour
of less than 10-\7\).
b. The system must be shown not susceptible to inadvertent
pretensioner actuation as a result of wear and tear, or inertia loads
resulting from in-flight or ground maneuvers likely to be experienced
in service.
c. The seated occupant must not be seriously injured as a result of
inadvertent pretensioner actuation.
d. Inadvertent pretensioner activation must not cause a hazard to
the airplane, nor cause serious injury to anyone who may be positioned
close to the retractor or belt (e.g., seated in an adjacent seat or
standing adjacent to the seat).
12. Availability of the Pretensioner Function Prior to Flight:
The design must provide means for a crewmember to verify the
availability of the pretensioner function prior to each flight, or the
probability of failure of the pretensioner function must be
demonstrated to be extremely remote (i.e., average probability per
flight hour of less than 10-\7\) between inspection
intervals.
13. Incorrect Seat Belt Orientation:
The system design must ensure that any incorrect orientation
(twisting) of the seat belt does not compromise the pretensioner
protection function.
14. Contamination Protection:
The pretensioner mechanisms and controls must be protected from
external contamination associated with that which could occur on or
around passenger seating.
15. Prevention of Hazards:
The pretensioner system must not induce a hazard to passengers in
case of fire, nor create a fire hazard, if activated.
16. Functionality After Loss of Power:
The system must function properly after loss of normal airplane
electrical power, and after a transverse separation in the fuselage at
the most critical location. A separation at the location of the system
does not have to be considered.
Issued in Des Moines, Washington, on June 22, 2020.
James E. Wilborn,
Acting Manager, Transport Standards Branch, Policy and Innovation
Division, Aircraft Certification Service.
[FR Doc. 2020-13760 Filed 7-9-20; 8:45 am]
BILLING CODE 4910-13-P
