[Federal Register Volume 86, Number 48 (Monday, March 15, 2021)]
[Rules and Regulations]
[Pages 14231-14232]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-05290]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2020-0404; Special Conditions No. 25-783-SC]


Special Conditions: B/E Aerospace, Bombardier Model CL-600-2B16 
(604 Variant) Airplane; Seats With Pretensioner Restraint Systems

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the Bombardier Inc. 
(Bombardier) Model CL-600-2B16 (604 variant) airplane. This airplane, 
as modified by B/E Aerospace, 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 a 3-point shoulder harness incorporating a 
pretensioner restraint system. 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 on B/E Aerospace on March 15, 2021.

FOR FURTHER INFORMATION CONTACT: Shannon Lennon, Human-Machine 
Interface Section, AIR-626, Technical Innovation Policy Branch, Policy 
and Innovation Division, Aircraft Certification Service, Federal 
Aviation Administration, 2200 South 216th Street, Des Moines, 
Washington 98198; telephone and fax 206-231-3209; email 
shannon.lennon@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

    On June 7, 2019, B/E Aerospace applied for a supplemental type 
certificate for seats with 3-point harness and pretensioner restraint 
systems on Bombardier Model CL-600-2B16 (604 variant) airplanes. The 
604 variant is a derivative of the Bombardier Model CL-600-2B16 
airplane currently approved under Type Certificate No. A21EA. This 
airplane variant is a twin-engine, transport category airplane with 
seating for 22 passengers, including crew, and a maximum take-off 
weight of 47,600 pounds.

Type Certification Basis

    Under the provisions of title 14, Code of Federal Regulations (14 
CFR) 21.101, B/E Aerospace must show that the Bombardier Model CL-600-
2B16 (604 variant) airplane, as changed, continues to meet the 
applicable provisions of the regulations listed in Type Certificate No. 
A21EA 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 Bombardier Model CL-600-2B16 (604 
variant) 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 Bombardier Model CL-600-2B16 (604 variant) 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 Bombardier Model CL-600-2B16 (604 variant) airplane, as 
modified by B/E Aerospace, will incorporate the following novel or 
unusual design feature:
    Seats with a 3-point shoulder harness incorporating a pretensioner 
restraint system to prevent head injuries.

Discussion

    B/E Aerospace has developed a system in which a pretensioning 
automotive retractor eliminates slack in the 3-point shoulder harness, 
pulling the occupant back into the seat prior to impact. This has the 
effect of reducing forward translation of the occupant (reduced head 
arc), while reducing the loads in the shoulder harness. B/E Aerospace 
will install, in Bombardier Model CL-600-2B16 (604 variant) airplanes, 
seats that incorporate a 3-point harness and pretensioner restraint 
system to protect seat occupants from head injuries.
    Over the past 10 years, multiple sensor-driven systems have been 
installed in various airplanes to meet improved crashworthiness 
regulations. A sensor-driven system is defined as any system that 
activates due to a signal sent by an impact-triggered inertial sensor. 
These types of systems include a lap-belt airbag, a structure-mounted 
airbag, and a 3-point harness and pretensioner restraint system.
    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 unlikely event of an emergency 
landing. Special conditions, pertinent regulations, and guidance have 
been published, relating to other or existing restraint systems. 
However, the use of a pretensioner restraint system with a 3-point 
harness 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 activates, because the upper torso excursion would be 
interrupted by activation of the shoulder harness. This could result in 
the head-injury criteria 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.
    The ideal triangular maximum-severity pulse is defined in Advisory 
Circular 25.562-1B, ``Dynamic Evaluation of Seat Restraint Systems and 
Occupant Protection on Transport Airplanes with Change 1,'' dated 
January 10, 2006. For evaluating and testing less-severe pulses to 
assess 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 these special conditions.
    Additionally, the pretensioner might not provide protection, after 
actuation,

[[Page 14232]]

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 activate is 
unnecessarily low, the protection offered by the pretensioner may be 
lost by the time a second larger impact occurs.
    The existing regulations do not adequately address seats with 
pretensioner restraint systems. Therefore, the proposed configuration 
requires special conditions.
    Special conditions 1 through 5 address ensuring 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. Special conditions 6 
through 11 address maintenance and reliability of the pretensioner 
system, including any outside influences on the mechanism, to ensure it 
functions as intended.
    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.

Discussion of Comments

    The FAA issued Notice of Proposed Special Conditions No. 25-20-04-
SC for the Bombardier Model CL-600-2B16 (604 variant) airplane, which 
was published in the Federal Register on September 4, 2020 (85 FR 
55198). The FAA received responses from four commenters supporting the 
special conditions. The special conditions are adopted as proposed.

Applicability

    As discussed above, these special conditions are applicable to the 
Bombardier Model CL-600-2B16 (604 variant) airplane. Should B/E 
Aerospace apply at a later date for a supplemental type certificate to 
modify any other model included on Type Certificate No. A21EA to 
incorporate the same novel or unusual design feature, these special 
conditions would apply to that model as well.

Conclusion

    This action affects only a certain novel or unusual design feature 
on one model of airplanes. 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 Bombardier Model CL-600-2B16 (604 
variant), as modified by B/E Aerospace.
    In addition to the requirements of Sec.  25.562, forward-facing 
passenger seats incorporating pretensioner restraint systems must meet 
the following:
    1. Head Injury Criteria--The Head Injury Criteria value must not 
exceed 1,000 units 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.
    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 10-7).
    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).
    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 10-7) between inspection intervals.
    7. Incorrect Seatbelt Orientation--The system design must ensure 
that any incorrect orientation (twisting) of the seatbelt 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.
    11. High-intensity Radiated Fields (HIRF) and Lightning 
Protection--For airplanes that do not already incorporate 14 CFR 
25.1316 and 25.1317 into their certification basis, the equipment must 
meet the applicable requirements of Sec. Sec.  25.1316 and 25.1317. 
Electrostatic discharge must also be considered in the design and 
testing of the equipment.

    Issued in Kansas City, Missouri, on February 17, 2021.
Patrick R. Mullen,
Manager, Technical Innovation Policy Branch, Policy and Innovation 
Division, Aircraft Certification Service.
[FR Doc. 2021-05290 Filed 3-12-21; 8:45 am]
BILLING CODE 4910-13-P


