Proposed Rule2023-10071
Special Conditions: The Boeing Company Model 777 Series Airplanes; Passenger Seats With Pretensioner Restraint Systems
Primary source
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Published
May 11, 2023
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
This action proposes special conditions for Boeing Company (Boeing) Model 777 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 pretensioner restraint systems installed on passenger seats. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These proposed special conditions contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards.
Full Text
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<title>Federal Register, Volume 88 Issue 91 (Thursday, May 11, 2023)</title>
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[Federal Register Volume 88, Number 91 (Thursday, May 11, 2023)]
[Proposed Rules]
[Pages 30262-30264]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2023-10071]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2022-1740; Notice No. 25-23-01-SC]
Special Conditions: The Boeing Company Model 777 Series
Airplanes; Passenger Seats With Pretensioner Restraint Systems
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed special conditions.
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SUMMARY: This action proposes special conditions for Boeing Company
(Boeing) Model 777 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 pretensioner restraint systems
installed on passenger seats. The applicable airworthiness regulations
do not contain adequate or appropriate safety standards for this design
feature. These proposed special conditions contain the additional
safety standards that the Administrator considers necessary to
establish a level of safety equivalent to that established by the
existing airworthiness standards.
DATES: Send comments on or before June 26, 2023.
ADDRESSES: Send comments identified by Docket No. FAA-2022-1740 using
any of the following methods:
<bullet> Federal eRegulations Portal: Go to <a href="https://www.regulations.gov/">https://www.regulations.gov/</a> and follow the online instructions for sending
your comments electronically.
<bullet> Mail: Send comments to Docket Operations, M-30, U.S.
Department of Transportation (DOT), 1200 New Jersey Avenue SE, Room
W12-140, West Building Ground Floor, Washington, DC 20590-0001.
<bullet> Hand Delivery or Courier: Take comments to Docket
Operations in Room W12-140 of the West Building Ground Floor at 1200
New Jersey Avenue SE, Washington, DC, between 9 a.m. and 5 p.m., Monday
through Friday, except Federal holidays.
<bullet> Fax: Fax comments to Docket Operations at 202-493-2251.
<bullet> Docket: Background documents or comments received may be
read at <a href="https://www.regulations.gov/">https://www.regulations.gov/</a> at any time. Follow the online
instructions for accessing the docket or go to Docket Operations in
Room W12-140 of the West Building Ground Floor at 1200 New Jersey
Avenue SE, Washington, DC, between 9 a.m. and 5 p.m., Monday through
Friday, except Federal holidays.
FOR FURTHER INFORMATION CONTACT: Shannon Lennon, Cabin Safety, AIR-624,
Technical Policy Branch, Policy and Standards Division, Aircraft
Certification Service, Federal Aviation Administration, 2200 South
216th Street, Des Moines, Washington 98198; telephone and fax 206-231-
3209; email <a href="/cdn-cgi/l/email-protection#116279707f7f7e7f3f7d747f7f7e7f517770703f767e67"><span class="__cf_email__" data-cfemail="a9dac1c8c7c7c6c787c5ccc7c7c6c7e9cfc8c887cec6df">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
Comments Invited
The FAA invites interested people to take part in this rulemaking
by sending written comments, data, or views. The most helpful comments
reference a specific portion of the proposed special conditions,
explain the reason for any recommended change, and include supporting
data.
The FAA will consider all comments received by the closing date for
comments, and will consider comments filed late if it is possible to do
so without incurring delay. The FAA may change these special conditions
based on the comments received.
Privacy
Except for Confidential Business Information (CBI) as described in
the following paragraph, and other information as described in title
14, Code of Federal Regulations (14 CFR) 11.35, the FAA will post all
comments received without change to <a href="https://www.regulations.gov/">https://www.regulations.gov/</a>,
including any personal information you provide. The FAA will also post
a report summarizing each substantive verbal contact received about
these special conditions.
Confidential Business Information
Confidential Business Information (CBI) is commercial or financial
information that is both customarily and actually treated as private by
its owner. Under the Freedom of Information Act (FOIA) (5 U.S.C. 552),
CBI is exempt from public disclosure. If your comments responsive to
these special conditions contain commercial or financial information
that is customarily treated as private, that you actually treat as
private, and that is relevant or responsive to these special
conditions, it is important that you clearly designate the submitted
comments as CBI. Please mark each page of your submission containing
CBI as ``PROPIN.'' The FAA will treat such marked submissions as
confidential under the FOIA, and the indicated comments will not be
placed in the public docket of these special conditions. Send
submissions containing CBI to the individual listed in the For Further
Information Contact section below. Comments the FAA receives, which are
not specifically designated as CBI, will be placed in the public docket
for these special conditions.
Background
On September 30, 2021, Boeing applied for an amendment to Type
Certificate No. T00001SE for Boeing Model 777 series airplanes. These
airplanes, currently approved under Type Certificate No. T00001SE, are
twin-engine, transport-category airplanes with maximum seating for 495
[[Page 30263]]
passengers and a maximum takeoff weight of 775,000 pounds.
Type Certification Basis
Under the provisions of 14 CFR 21.101, Boeing must show that Model
777 series airplanes meet the applicable provisions of the regulations
listed in Type Certificate No. T00001SE, 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 777 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 777 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
Boeing Model 777 series airplanes will incorporate the following
novel or unusual design feature:
Forward-facing seats incorporating a shoulder harness with
pretensioner device, otherwise known as a pretensioner restraint
system, which is intended to protect the occupants from head injuries.
Discussion
Boeing will install, in Model 777 series airplanes, forward-facing
seats that incorporate a shoulder harness with a pretensioner system,
for head-injury protection, at each seat place.
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
relate to other restraint systems. However, the use of pretensioners in
the restraint system on transport-airplane seats is a novel design.
The pretensioner restraint system utilizes a retractor that
eliminates slack in the shoulder harness and pulls the occupant back
into the seat prior to impact. This has the effect of reducing forward
translation of the occupant, reducing head arc, and reducing loads in
the shoulder harness.
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. Such excursion 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 1 in these special
conditions.
The ideal triangular maximum-severity pulse is defined in Advisory
Circular (AC) 25.562-1B, ``Dynamic Evaluation of Seat Restraint Systems
and Occupant Protection on Transport Airplanes.'' 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.
Conditions 1 through 4 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 5 through 10 address
maintenance and reliability of the pretensioner system, including any
outside influences on the mechanism, to ensure it functions as
intended.
The proposed special conditions contain the additional safety
standards that the Administrator considers necessary to establish a
level of safety equivalent to that established by the existing
airworthiness standards.
Applicability
As discussed above, these proposed special conditions are
applicable to the 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 apply to the other model as well.
Conclusion
This action affects only a certain novel or unusual design feature
on one model series of airplanes. It is not a rule of general
applicability.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
Authority Citation
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701, 44702, and
44704.
The Proposed Special Conditions
Accordingly, the Federal Aviation Administration (FAA) proposes the
following special conditions as part of the type certification basis
for Boeing Model 777 series airplanes.
In addition to the requirements of Sec. 25.562, forward-facing
passenger seats with pretensioner restraint systems must meet the
following:
(1) 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 anthropomorphic test device (ATD) has no
apparent contact with the seat/structure but has contact with an
airbag, a HIC unlimited scored
[[Page 30264]]
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.
(2) 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.
(3) 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.
(4) Occupants Adopting the Brace Position
Occupants in the traditional brace position when the pretensioner
activates must not experience adverse effects from the pretensioner
activation.
(5) 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<SUP>-7</SUP>).
(b) The system must be shown not to be susceptible to inadvertent
pretensioner actuation as a result of wear and tear, nor 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 actuation 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).
(6) 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<SUP>-7</SUP>) between inspection intervals.
(7) 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.
(8) Contamination Protection
The pretensioner mechanisms and controls must be protected from
external contamination associated with that which could occur on or
around passenger seating.
(9) Prevention of Hazards
The pretensioner system must not induce a hazard to passengers in
case of fire, nor create a fire hazard, if activated.
(10) 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 May 5, 2023.
Suzanne A. Masterson,
Acting Manager, Technical Policy Branch, Policy and Standards Division,
Aircraft Certification Service.
[FR Doc. 2023-10071 Filed 5-10-23; 8:45 am]
BILLING CODE 4910-13-P
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