[Federal Register Volume 83, Number 177 (Wednesday, September 12, 2018)]
[Rules and Regulations]
[Pages 46101-46103]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-19752]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2016-4136; Special Conditions No. 25-621A-SC]


Special Conditions: The Boeing Company (Boeing), Model 777 Series 
Airplanes; Dynamic Test Requirements for Single Occupant Oblique Seats, 
With or Without Airbag Devices or 3-Point Restraints

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Amended final special conditions; request for comments.

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SUMMARY: These amended special conditions are issued for the Boeing 
Model 777 series airplanes. This amendment states that the Boeing Model 
777 series airplanes oblique (side-facing) seats may be installed at an 
angle of 18 to 45 degrees to the airplane centerline and may include a 
3-point or airbag restraint system, or both, for occupant restraint and 
injury protection. This airplane will have novel or unusual design 
features when compared to the state of technology envisioned in the 
airworthiness standards for transport category airplanes. These design 
features are oblique (side-facing) single-occupant passenger seats 
equipped with or without airbag devices or 3-point restraints. 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: This action is effective on The Boeing Company on September 12, 
2018. Send comments on or before October 29, 2018.

ADDRESSES: Send comments identified by Docket No. FAA-2016-4136 using 
any of the following methods:
     Federal eRegulations Portal: Go to http://www.regulations.gov/ and follow the online instructions for sending 
your comments electronically.
     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.
     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.
     Fax: Fax comments to Docket Operations at 202-493-2251.
    Privacy: The FAA will post all comments it receives, without 
change, to http://www.regulations.gov/, including any personal 
information the commenter provides. Using the search function of the 
docket website, anyone can find and read the electronic form of all 
comments received into any FAA docket, including the name of the 
individual sending the comment (or signing the comment for an 
association, business, labor union, etc.). DOT's complete Privacy Act 
Statement can be found in the Federal Register published on April 11, 
2000 (65 FR 19477-19478).
    Docket: Background documents or comments received may be read at 
http://www.regulations.gov/ 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: John Shelden, 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 206-231-3214; email [email protected].

SUPPLEMENTARY INFORMATION: The substance of these special conditions 
has been published in the Federal Register for public comment in 
several prior instances with no substantive comments received. The FAA 
therefore finds it unnecessary to delay the effective date and finds 
that good cause exists for making these special conditions effective 
upon publication in the Federal Register.

Comments Invited

    We invite 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 special conditions, explain the 
reason for any recommended change, and include supporting data.
    We will consider all comments we receive by the closing date for 
comments. We may change these special conditions based on the comments 
we receive.

Background

    On November 22, 2017, Boeing applied for an amendment to Type

[[Page 46102]]

Certificate No. T00001SE for the installation of oblique (side-facing) 
passenger seats with or without airbag devices or 3-point restraints in 
the Boeing Model 777 series airplanes. The Boeing Model 777 series 
airplanes are twin-engine, transport category airplanes with a maximum 
certified passenger capacity of up to 550 and a maximum takeoff weight 
of approximately 775,000 lbs.

Type Certification Basis

    Under the provisions of title 14, Code of Federal Regulations (14 
CFR) 21.101, Boeing must show that the 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 (i.e., 14 CFR part 25) do not contain adequate or 
appropriate safety standards for the Boeing Model 777 series airplanes 
because of novel or unusual design features, 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, the 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

    The business-class seating configuration Boeing proposes is novel 
or unusual due to the seat installation at 30 degrees to the airplane 
centerline, the airbag-system installation, and the seat/occupant 
interface with the surrounding furniture that introduces occupant 
alignment and loading concerns. The proposed business-class seating 
configuration is also beyond the limits of current acceptable 
equivalent-level-of-safety findings. These oblique (side-facing) seats 
may be installed at an angle of 18 to 45 degrees to the airplane 
centerline and may include a 3-point or airbag restraint system, or 
both, for occupant restraint and injury protection.
    The existing regulations do not provide adequate or appropriate 
safety standards for occupants of oblique-angled seats with airbag 
systems. To provide a level of safety that is equivalent to that 
afforded occupants of forward- and aft-facing seats, additional 
airworthiness standards, in the form of special conditions, are 
necessary. These special conditions supplement part 25 and, more 
specifically, supplement Sec. Sec.  25.562 and 25.785.
    The requirements contained in these special conditions consist of 
both test conditions and injury pass/fail criteria.

Discussion

    The FAA has been conducting and sponsoring research on appropriate 
injury criteria for oblique (side-facing) seat installations. However, 
the FAA research program is not complete and we may update these 
criteria as we obtain further research results. To reflect current 
research findings, the FAA issued policy statement PS-ANM-25-03-R1 to 
update injury criteria for fully side-facing seats, and policy 
statement PS-AIR-25-27, to define injury criteria for oblique (side-
facing) seats.
    The proposed Boeing Model 777 series airplanes business-class seat 
installation is novel such that the current Boeing Model 777 series 
airplanes certification basis does not adequately address protection of 
the occupant's neck and spine for seat configurations that are 
positioned at an angle greater than 18 degrees from the airplane 
centerline. The FAA issued special conditions No. 25-569-SC for Model 
777-300ER airplanes on September 25, 2014, and special conditions No. 
25-621-SC for certain Model 777-300ER airplanes on August 3rd, 2016. 
These special conditions contained injury criteria for oblique seats 
based on the best knowledge the FAA had at the time. These special 
conditions for oblique seat installations do not adequately address 
oblique seats, reflecting the current research results, with or without 
3-point or airbag restraint systems. Therefore, Boeing's proposed 
configuration will require amended special conditions.
    The installation of passenger seats at angles of 18 to 45 degrees 
to the airplane centerline are unique due to the seat/occupant 
interface with the surrounding furniture that introduces occupant 
alignment/loading concerns with or without the installation of a 3-
point or airbag restraint system, or both. On-going research has 
invalidated previously released special conditions for oblique (side-
facing) seat installations. These updated special conditions further 
address potential injuries to the occupant's neck and spine. As a 
result, these special conditions replace special conditions 25-569-SC 
and 25-621-SC.
    FAA-sponsored research has found that an un-restrained 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 an FAA H-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 spine tension 
limit selected is conservative with respect to other aviation injury 
criteria since it corresponds to a no-injury loading condition.
    As noted in the special conditions for each airbag restraint 
system, because an airbag restraint system is essentially a single use 
device, there is the potential that it could deploy under crash 
conditions that are not sufficiently severe as to require head injury 
protection from the airbag restraint system. Since an actual crash is 
frequently composed of a series of impacts before the airplane comes to 
rest, this could render the airbag restraint system useless if a larger 
impact follows the initial impact. This situation does not exist with 
energy absorbing pads or upper torso restraints, which tend to provide 
protection according to the severity of the impact. Therefore, the 
installation of the airbag restraint system should be such that the 
airbag restraint system will provide protection when it is required, 
and will not expend its protection when it is not needed.
    Because these airbag restraint systems may or may not activate 
during various crash conditions, the injury criteria listed in these 
special conditions and in Sec.  25.562 must be met in an event that is 
slightly below the activation level of the airbag restraint system. If 
an airbag restraint system is included with the oblique seats, the 
system must meet the requirements in one of the airbag (inflatable 
restraint) special conditions applicable to the Boeing Model 777 series 
airplanes.

[[Page 46103]]

    These amended special conditions will provide head injury criteria, 
neck injury criteria, spine injury criteria, and body-to-wall contact 
criteria. They 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 special conditions are applicable to the 
Boeing Model 777 series airplane. 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 certain novel or unusual design features 
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 the Boeing Model 777 series airplanes.

Side-Facing Seats Special Conditions

    In addition to the requirements of Sec.  25.562:

1. Head Injury Criteria (HIC)

    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 HIC unlimited score in excess of 1,000 is acceptable, 
provided the HIC15 score for that contact (calculated in accordance 
with 49 CFR 571.208) is less than 700.

2. Body-to-Wall/Furnishing Contact

    If a seat is installed aft of structure (e.g., interior wall or 
furnishings) that 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, 
different yaw angles could result in different airbag device 
performance, then additional analysis or separate tests may be 
necessary to evaluate performance.

3. 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 a reason to also 
consider that the neck-injury potential would be higher for impacts 
below the airbag-device deployment threshold.
    a. 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:

i. Fzc = 1,530 lbs for tension
ii. Fzc = 1,385 lbs for compression
iii. Myc = 229 lb-ft in flexion
iv. Myc = 100 lb-ft in extension
    b. In addition, peak upper-neck Fz must be below 937 
lbs. in tension and 899 lbs. in compression.
    c. Rotation of the head about its vertical axis, relative to the 
torso is limited to 105 degrees in either direction from forward-
facing.
    d. The neck must not impact any surface that would produce 
concentrated loading on the neck.

4. Spine and Torso Injury Criteria:

    a. The lumbar spine tension (Fz) cannot exceed 1,200 
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 direction) acceleration exceeding 20 g 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.

5. 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.

6. 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.

7. 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.

    Issued in Des Moines, Washington, on September 5, 2018.
Victor Wicklund,
Manager, Transport Standards Branch, Policy and Innovation Division, 
Aircraft Certification Service.
[FR Doc. 2018-19752 Filed 9-11-18; 8:45 am]
 BILLING CODE 4910-13-P


