[Federal Register Volume 86, Number 100 (Wednesday, May 26, 2021)]
[Rules and Regulations]
[Pages 28250-28253]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-11136]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2021-0228; Special Conditions No. 25-787-SC]


Special Conditions: Haeco Cabin Solutions, Boeing Commercial 
Airplanes Model 737-800 Airplane; Structure-Mounted Airbags

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the Boeing Commercial 
Airplanes (Boeing) Model 737-800 airplane. This airplane, as modified 
by Haeco Cabin Solutions (Haeco), 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 structure-mounted airbags designed to protect each occupant 
from serious head injury in the event of an emergency landing. The 
applicable airworthiness regulations do not contain adequate or 
appropriate safety standards for this

[[Page 28251]]

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 May 26, 2021.

FOR FURTHER INFORMATION CONTACT: John Shelden, Human Machine Interface, 
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.

SUPPLEMENTARY INFORMATION:

Background

    On September 1, 2020, Haeco applied for a supplemental type 
certificate for structure-mounted airbags in the Boeing Model 737-800 
airplane. The Boeing Model 737-800 airplane, which is a derivative of 
the Boeing Model 737 airplane currently approved under Type Certificate 
No. A16WE, is a twin-engine, transport-category airplane with seating 
for 189 passengers and a maximum takeoff weight of 174,200 pounds.

Type Certification Basis

    Under the provisions of title 14, Code of Federal Regulations (14 
CFR) 21.101, Haeco must show that the Boeing Model 737-800 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 737-800 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 applicant apply for a supplemental type 
certificate to modify any other model included on the same type 
certificate 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 737-800 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 14 CFR 11.19, in 
accordance with Sec.  11.38, and they become part of the type 
certification basis under Sec.  21.101.

Novel or Unusual Design Features

    The Boeing Model 737-800 airplane will incorporate the following 
novel or unusual design features:
    Airbags mounted to structure to prevent head injury.

Discussion

    Haeco will install structure-mounted airbags instead of inflatable 
lap belts as a means to protect each occupant from serious injury in 
the event of an emergency landing, as required by Sec.  25.562(c)(5), 
on 737-800 airplanes.
    Such use of airbags to provide injury protection for the occupant 
is a novel or unusual feature for this airplane model, and the 
applicable airworthiness regulations do not contain adequate or 
appropriate airworthiness standards for these design features. 
Therefore, special conditions are needed to address requirements 
particular to installation of airbags in this manner.
    Special conditions exist for airbags installed on seat belts, known 
as inflatable lap belts, which have been installed on transport 
airplane passenger seats. Structure-mounted airbags, although a novel 
design, were first introduced on Jetstream Aircraft Limited Model 4100 
series airplanes, which resulted in issuance of Special Conditions 25-
ANM-127 on May 14, 1997. These special conditions supplemented 14 CFR 
part 25 and, more specifically, Sec. Sec.  25.562 and 25.785.
    The structure-mounted airbag, similar to the inflatable lap belt, 
is designed to limit occupant forward excursion in the event of an 
emergency landing. These airbags will reduce the potential for serious 
injury, including reducing the head-injury criterion measurement 
defined in part 25. However, structure-mounted airbags function 
similarly as automotive airbags, where the airbag deploys from 
furniture located in front of the passenger, relative to the airplane's 
direction of flight, forming a barrier between the structure and 
occupant. Also, unlike the inflatable lap belt, the structure-mounted 
airbag does not move with the occupant. To account for out-of-position 
and brace-position occupants, the airbag is designed to conform to the 
curvature of the exposed structure in the head-strike zone.
    Because the airbag system is essentially a single-use device, it 
could deploy under crash conditions that are not sufficiently so severe 
as to require the injury protection the airbag system provides. Because 
an actual crash is frequently composed of a series of impacts before 
the airplane comes to rest, a larger impact following the initial 
impact could render the airbag system unavailable. This potential 
situation does not exist with standard upper-torso restraints, which 
tend to provide continuous protection regardless of impact severity, or 
number of impacts, in a crash event. Therefore, the airbag system 
installation should be such that it provides protection, when it is 
required, by not expending its protection when it is not required. If 
the airbag deployment threshold is unnecessarily low, the airbag would 
need to continue to provide protection when an impact requiring 
protection occurs.
    These special conditions are based upon Special Conditions 25-605-
SC for the Boeing Model 787-9 airplanes equipped with B/E Aerospace 
Super-Diamond model business-class passenger seats and associated 
furniture. Additionally, the special conditions address protection of 
the occupant's neck and spine for the structure-mounted airbag 
deployment. When using the HIC15 head-injury method for airbag impacts 
(calculated in accordance with 49 CFR 571.208) the neck and spine 
limits are included as part of the allowance.
    These additional conditions are based on special conditions issued 
previously on oblique seats. 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.

Discussion of Comments

    The FAA issued Notice of Proposed Special Conditions No. 25-21-01-
SC for the Boeing Model 737-800 series airplane, which was published in 
the Federal Register on March 16, 2021 (86 FR 14387). No comments were 
received, and the special conditions are adopted as proposed.

Applicability

    As discussed above, these special conditions are applicable to the 
Boeing Model 737-800 airplane as modified by Haeco. Should Haeco apply 
at a later date for a supplemental type certificate to modify any other 
model included on Type Certificate No. A16WE to incorporate the same 
novel or unusual design feature, these special conditions would apply 
to that model as well.
    Under standard practice, the effective date of final special 
conditions would be 30 days after the date of publication in the 
Federal Register. However, as the

[[Page 28252]]

certification date is imminent, the FAA finds that good cause exists to 
make these special conditions effective upon publication.

Conclusion

    This action affects only a certain novel or unusual design features 
on one model of airplane. It is not a rule of general applicability and 
affects only the applicant who applied to the FAA for approval of these 
features on the airplane.

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 737-800 airplanes, as 
modified by Haeco Cabin Solutions:
    1. The applicant must demonstrate by test that the structure-
mounted airbag will deploy and provide protection under crash 
conditions where it is necessary to prevent serious injury to a 50th 
percentile occupant, as specified in Sec.  25.562. The means of 
protection must provide a consistent approach to energy absorption for 
a range of occupants, from a two-year-old child to a 95th percentile 
male. In addition, the following situations should be considered:
    1. The seat occupant is holding an infant.
    2. The seat occupant is a child in a child restraint device.
    3. The seat occupant is a child not using a child restraint device.
    4. The seat occupant is a pregnant woman.

a. Head-Injury Criteria

    Compliance with Sec.  25.562(c)(5) is required, except that, if the 
ATD has no apparent contact with the seat/structure but has contact 
with an airbag, a head-injury criterion (HIC) unlimited score in excess 
of 1000 is acceptable, provided the HIC15 score (calculated in 
accordance with 49 CFR 571.208) for that contact is less than 700.

b. Body-to-Wall/Furnishing Contact

    If a seat is installed aft of structure (e.g., 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 or 
tests may be required to demonstrate that the injury criteria are met 
for the area that an occupant could contact. For example, if different 
yaw angles could result in different airbag performance, then 
additional analysis or separate tests may be necessary to evaluate 
performance.

c. Neck-Injury Criteria

    The seating system must protect the occupant from experiencing 
serious neck injury. The assessment of neck injury must be conducted 
with the airbag device activated, unless there is reason to also 
consider that the neck-injury potential would be higher for impacts 
below the airbag-device deployment threshold.
    (1) 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:

    (a) Fzc = 1,530 lb for tension
    (b) Fzc = 1,385 lb for compression
    (c) Myc = 229 lb-ft in flexion
    (d) Myc = 100 lb-ft in extension

    (2) In addition, peak Fz must be below 937 lb in tension 
and 899 lb in compression.
    (3) Rotation of the head about its vertical axis, relative to the 
torso, is limited to 105 degrees in either direction from forward-
facing.
    (4) The neck must not impact any surface that would produce 
concentrated loading on the neck.

d. ATD and Test Conditions

    Longitudinal tests conducted to measure the injury criteria above 
must be performed with the FAA Hybrid III ATD, as described in SAE 
1999-01-1609, ``A Lumbar Spine Modification to the Hybrid III ATD for 
Aircraft Seat Tests.'' The tests must be conducted with an undeformed 
floor, at the most-critical yaw cases for injury, and with all lateral 
structural supports (e.g., armrests or walls) installed.
    Note: Applicant 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.
    2. The structure-mounted airbag must provide adequate protection 
for each occupant regardless of the number of occupants of the seat 
assembly.
    3. The structure-mounted airbag system must not be susceptible to 
inadvertent deployment as a result of wear and tear, or inertial loads 
resulting from in-flight or ground maneuvers (including gusts and hard 
landings) likely to be experienced in service.
    4. The applicant must demonstrate that an inadvertent deployment 
that could cause injury to a standing or sitting person is improbable. 
Inadvertent deployment must not cause injury to anyone who may be 
positioned close to the structure-mounted airbag (e.g., seated in an 
adjacent seat, or standing adjacent to the airbag installation or the 
subject seat). Cases where a structure-mounted airbag is inadvertently 
deployed near a seated occupant or an empty seat must be considered.
    5. Inadvertent deployment of the structure-mounted airbag during 
the most critical part of flight will either not cause a hazard to the 
airplane or is extremely improbable.
    6. Deployment of the structure-mounted airbag must not introduce 
hazards or injury mechanisms to the seated occupant, including 
occupants in the brace position. Deployment of the structure-mounted 
airbag must also not result in injuries that could impede rapid exit 
from the airplane.
    7. Effects of the deflection and deformation of the structure to 
which the airbag is attached must be taken into account when evaluating 
deployment and location of the inflated airbag. The effect of loads 
imposed by airbag deployment, or stowed components where applicable, 
must also be taken into account.
    8. The applicant must demonstrate that the structure-mounted 
airbag, when deployed, does not impair access to the seatbelt- or 
harness-release means, and must not hinder evacuation. This will 
include consideration of adjacent seat places and the aisle.
    9. The airbag, once deployed, must not adversely affect the 
emergency-lighting system, and must not block escape-path lighting to 
the extent that the light(s) no longer meet their intended function.
    10. The structure-mounted airbag must not impede occupants' rapid 
exit from the airplane 10 seconds after its deployment.
    11. Where structure-mounted airbag systems are installed in or 
close to passenger evacuation routes (other than for the passenger seat 
for which the airbag is installed), possibility of impact on emergency 
evacuation (e.g., hanging in the aisle, potential trip hazard, etc.) 
must be evaluated.
    12. The airbag electronic system must be designed to be protected 
from lightning per Sec.  25.1316(b), and high-

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intensity radiated fields per Sec.  25.1317(c).
    13. The structure-mounted airbag system must not contain or release 
hazardous quantities of gas or particulate matter into the cabin.
    14. The structure-mounted airbag installation must be protected 
from the effects of fire such that no hazard to occupants will result.
    15. The inflatable bag material must meet the 2.5-inches-per-minute 
horizontal flammability test defined in 14 CFR part 25, appendix F, 
part I, paragraph (a)(1)(iv).
    16. The design of the structure-mounted airbag system must protect 
the mechanisms and controls from external contamination associated with 
that which could occur on or around passenger seating.
    17. The structure-mounted airbag system must have a means to verify 
the integrity of the structure-mounted airbag activation system.
    18. The applicant must provide installation limitations to ensure 
installation compatibility between the seat design and opposing 
monument or structure.

    Issued in Kansas City, MO, on May 21, 2021.
Patrick R. Mullen,
Manager, Technical Innovation Policy Branch, Policy and Innovation 
Division, Aircraft Certification Service.
[FR Doc. 2021-11136 Filed 5-25-21; 8:45 am]
BILLING CODE 4910-13-P


