Document ID: FAA-2019-0236-0004
Agency: faa
Document Type: Rule
Title: Special Conditions: Boeing Model 787 Series Airplanes; Seats with Inertia Locking Devices
Posted Date: 2019-06-10T04:00Z

[Federal Register Volume 84, Number 111 (Monday, June 10, 2019)]
[Rules and Regulations]
[Pages 26739-26741]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-12121]

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 Rules and Regulations
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  Federal Register / Vol. 84, No. 111 / Monday, June 10, 2019 / Rules 
and Regulations  

[[Page 26739]]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2019-0236; Special Conditions No. 25-745-SC]

Special Conditions: Boeing Model 787 Series Airplanes; Seats With 
Inertia Locking Devices

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the Boeing Model 787 
series airplane. 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 seats with inertia locking devices. 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 June 10, 2019.

FOR FURTHER INFORMATION CONTACT: Shannon Lennon, Cabin and Airframe 
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 February 14, 2019, Boeing applied for a change to Type 
Certificate No. T00021SE for seats with inertia locking devices in 
Model 787 series airplanes. The Model 787 series airplane is a twin-
engine transport-category airplane with a maximum takeoff weight of 
560,000 pounds and seating for 440 passengers.

Type Certification Basis

    Under the provisions of title 14, Code of Federal Regulations (14 
CFR) 21.101, Boeing must show that the Model 787 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 (i.e., 14 CFR part 25) do not contain adequate or 
appropriate safety standards for Boeing Model 787 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 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 787 series airplanes will incorporate the following 
novel or unusual design features:
    Seats with inertia locking devices (ILD).

Discussion

    Boeing will install, in Model 787 series airplanes, Thompson Aero 
Seating Ltd. passenger seats that can be translated in the fore and aft 
direction by an electrically powered motor (actuator) that is attached 
to the seat primary structure. Under typical service-loading 
conditions, the motor internal brake is able to translate the seat and 
hold the seat in the translated position. However, under the inertial 
loads of emergency-landing loading conditions specified in 14 CFR 
25.562, the motor internal brake may not be able to maintain the seat 
in the required position. The ILD is an ``active'' device intended to 
control seat movement (i.e., a system that mechanically deploys during 
an impact event) to lock the gears of the motor assembly in place. The 
ILD mechanism is activated by the higher inertial load factors that 
could occur during an emergency landing event. Each seat place 
incorporates two ILDs; one on either side of the seat pan. Only one ILD 
is required to hold an occupied seat in position during worst-case 
dynamic loading specified in Sec.  25.562.
    The ILD will self-activate only in the event of a predetermined 
airplane loading condition such as that occurring during crash or 
emergency landing, and will prevent excessive seat forward translation. 
A minimum level of protection must be provided if the seat-locking 
device does not deploy.
    The normal means of satisfying the structural and occupant 
protection requirements of Sec.  25.562 result in a non-quantified, but 
predictable, progressive structural deformation or reduction of injury 
severity for impact conditions less than the maximum specified by the 
rule. A seat using ILD technology, however, may involve a step change 
in protection for impacts below and above that at which the ILD 
activates and deploys to retain the seat pan in place. This could 
result in structural deformation or occupant injury output being higher 
at an intermediate impact condition than that resulting from the 
maximum impact condition. It is acceptable for such step-change 
characteristics to exist, provided the resulting output does not exceed 
the maximum allowable criteria at any condition at which the ILD does 
or does not deploy, up to the maximum severity pulse specified by the 
requirements.
    The ideal triangular maximum severity pulse is defined in Advisory 
Circular (AC) 25.562-1B. For the evaluation and testing of less-severe

[[Page 26740]]

pulses for purposes of assessing the effectiveness of the ILD 
deployment 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.
    Conditions 1 through 5 address ensuring that the ILD activates when 
intended in order to provide the necessary protection of occupants. 
This includes protection of a range of occupants under various accident 
conditions. Conditions 6 through 10 address maintenance and reliability 
of the ILD, including any outside influences on the mechanism, to 
ensure it functions as intended.
    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. 25-19-03-
SC, for the Boeing Model 787 series airplane, which was published in 
the Federal Register on April 29, 2019 (84 FR 17977). The FAA received 
responses from two commenters.
    One commenter writes:
    Seats are dynamically tested in upright positions to show 
compliance with 14 CFR part 25.562. In this specific installation, 
there is a mechanical or electrical actuation of the movement of the 
seat, and the following points of concern may raise:
    (1) If the motor loses electrical power before a crash during an 
actuation, can it lock the seat in a position other than that 
considered for [taxi, takeoff, and landing] TTL?
    (2) There should be included a Special Condition to address 
possible interference of lightning and high-intensity radiated fields 
on the motor or its commands;
    (3) Design features should be demanded to avoid the seat to be 
locked in an intermediate position (for example, because of fail in 
link between the seat structure and the actuator).
    The FAA clarifies, regarding the commenter's concerns about seat-
actuator motor disability and impact on the seat position due to loss 
of power or other conditions, the seat design includes a manual-
override feature to restore the seat in the required position. However, 
while the actuator motor is part of the seat-actuation system, this 
feature is not the subject of the proposed special conditions. Rather, 
the special conditions address the ILDs, which are a different 
component of the seat-actuation system and are intended to ensure that 
the seat position is maintained in the event that the structural 
capability of the actuator motor brake is exceeded during emergency-
landing conditions. The ILDs are a mechanical interlock feature and are 
not affected by loss of power or external electrical forces.
    Another commenter asks if such extra safety precautions as ILDs may 
potentially be implemented in other airplane models, adding that seats 
with inertia locking devices likely enhance air-travel safety.
    The FAA agrees that ILDs enhance airplane safety. It is possible 
that ILDs potentially will be incorporated into seat designs intended 
for installation on other airplane models. Incorporation of such a 
feature is contingent on the airplane manufacturer's determination to 
install seats that include ILDs as part of a seat-actuation system.
    The comments do not change the special conditions, and the special 
conditions are adopted as proposed.

Applicability

    As discussed above, these special conditions are applicable to 
Boeing Model 787 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 one 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 series airplanes.
    In addition to the requirements of Sec.  25.562, passenger seats 
incorporating an inertia locking device (ILD) must meet the following:
    1. Level of Protection Provided by ILD--It must be demonstrated by 
test that the seats and attachments, when subject to the emergency-
landing dynamic conditions specified in Sec.  25.562, and with one ILD 
not deployed, do not experience structural failure that could result 
in:
    a. Separation of the seat from the airplane floor.
    b. Separation of any part of the seat that could form a hazard to 
the seat occupant or any other airplane occupant.
    c. Failure of the occupant restraint or any other condition that 
could result in the occupant separating from the seat.
    2. Protection Provided Below and Above the ILD Actuation 
Condition--If step-change effects on occupant protection exist for 
impacts below and above that at which the ILD deploys, tests must be 
performed to demonstrate that the occupant is shown to be protected at 
any condition at which the ILD does or does not deploy, up to the 
maximum severity pulse specified by Sec.  25.562. Test conditions must 
take into account any necessary tolerances for deployment.
    3. Protection Over a Range of Crash Pulse Vectors--The ILD must be 
shown to function as intended for all test vectors specified in Sec.  
25.562.
    4. Protection During Secondary Impacts--The ILD activation setting 
must be demonstrated to maximize the probability of the protection 
being available when needed, considering a secondary impact that is 
above the severity at which the device is intended to deploy up to the 
impact loading required by Sec.  25.562.
    5. Protection of Occupants other than 50th Percentile--Protection 
of occupants for a range of stature from a two-year-old child to a 
ninety-five percentile male must be shown.
    6. Inadvertent Operation--It must be shown that any inadvertent 
operation of the ILD does not affect the performance of the device 
during a subsequent emergency landing.
    7. Installation Protection--It must be shown that the ILD 
installation is protected from contamination and interference from 
foreign objects.
    8. Reliability--The performance of the ILD must not be altered by 
the effects of wear, manufacturing tolerances, aging or drying of 
lubricants, and corrosion.
    9. Maintenance and Functional Checks--The design, installation, and 
operation of the ILD must be such that it is possible to functionally 
check the

[[Page 26741]]

device in place. Additionally, a functional check method and a 
maintenance check interval must be included in the seat installer's 
instructions for continued airworthiness (ICA) document.
    10. Release Function--If a means exists to release an inadvertently 
activated ILD, the release means must not introduce additional hidden 
failures that would prevent the ILD from functioning properly.

    Issued in Des Moines, Washington, on June 5, 2019.
Paul Siegmund,
Acting Manager, Transport Standards Branch, Policy and Innovation 
Division, Aircraft Certification Service.
[FR Doc. 2019-12121 Filed 6-7-19; 8:45 am]
 BILLING CODE 4910-13-P