Document ID: FAA-2016-5595-0019
Agency: faa
Document Type: Rule
Title: Airworthiness Directives: Zodiac Seats California LLC Seating Systems
Posted Date: 2017-05-24T04:00Z

[Federal Register Volume 82, Number 99 (Wednesday, May 24, 2017)]
[Rules and Regulations]
[Pages 23723-23731]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-10256]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2016-5595; Directorate Identifier 2015-NM-087-AD; 
Amendment 39-18871; AD 2017-09-09]
RIN 2120-AA64

Airworthiness Directives; Zodiac Seats California LLC Seating 
Systems

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for certain 
Zodiac Seats California LLC seating systems. This AD was prompted by a 
determination that the affected seating systems may cause serious 
injury to the occupant during forward impacts when subjected to certain 
inertia forces. This AD requires removing affected seating systems. We 
are issuing this AD to address the unsafe condition on these products.

DATES: This AD is effective June 28, 2017.

ADDRESSES:

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2016-
5595; or in person at the Docket Management Facility between 9 a.m. and 
5 p.m., Monday through Friday, except Federal holidays. The AD docket 
contains this AD, the regulatory evaluation, any comments received, and 
other information. The address for the Docket Office (phone: 800-647-
5527) is Docket Management Facility, U.S. Department of Transportation, 
Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 
New Jersey Avenue SE., Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Patrick Farina, Aerospace Engineer, 
Cabin Safety Branch, ANM-150L, FAA, Los Angeles Aircraft Certification 
Office (ACO), 3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: 
562-627-5344; fax: 562-627-5210; email: patrick.farina@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 by adding an AD that would apply to certain Zodiac Seats 
California LLC seating systems. The NPRM published in the Federal 
Register on April 20, 2016 (81 FR 23212) (``the NPRM''). The NPRM was 
prompted by a determination that the affected seating systems may cause 
serious injury to the occupant during forward impacts when subjected to 
certain inertia forces. The NPRM proposed to require removing affected 
seating systems. We are issuing this AD to prevent serious injury to 
the occupant during forward impacts in emergency landing conditions.
    After the NPRM comment period closed, we reopened the comment

[[Page 23724]]

period to allow additional time for interested parties to comment on 
the NPRM (81 FR 41466, June 27, 2016).

Comments

    We gave the public the opportunity to participate in developing 
this AD. The following presents the comments received on the NPRM and 
the FAA's response to each comment.

Request To Withdraw the NPRM

    The Industry Ad Hoc Committee (which consists of Bombardier, 
Embraer, HAECO Cabin Solutions, Zodiac Seats California, Zodiac Seats 
France, Zodiac Seats UK, and Zodiac Seats US) and Zodiac Seats 
California (commenting independently) questioned the basis for the 
requirements of the proposed AD. We infer they are requesting we 
withdraw the NPRM. The Industry Ad Hoc Committee and Zodiac Seats 
California stated the proposed AD is not supported on a technical basis 
and is based only on limited research. The Industry Ad Hoc Committee 
asked if there have been any aerospace incidents or accidents 
documenting the specific neck injuries being mitigated by the proposed 
AD. The Industry Ad Hoc Committee and Zodiac Seats California stated 
there has been no correlation to develop proper costs/benefits related 
to the type of injury mechanism specified in the NPRM with respect to 
actual accident injuries. The Industry Ad Hoc Committee and Zodiac 
Seats California cited multiple accidents where news and investigative 
reports from the accidents did not mention serious neck injuries.
    We do not agree to withdraw the NPRM. The intent of this AD is to 
provide a safe outcome for passengers during a survivable crash by 
preventing serious injuries, such as a transection of the neck during 
forward impacts in emergency landing conditions. We find that 
sufficient data exist to demonstrate that affected seating systems 
might cause serious injury to the occupant during forward impacts when 
subjected to certain inertia forces. We note that the commenters have 
identified several accidents that were survivable with seating systems 
that are not subject to this AD. The comparison of those seating 
systems to the ones identified in this AD is not valid.
    We have identified an unsafe condition and determined corrective 
action is required. Therefore, we have not revised this AD in this 
regard. We have provided additional details on the unsafe condition in 
the comment responses that follow.

Request To Revise Applicability To Exclude Seating Systems With a 
Certain Design

    Zodiac Seats California requested that we exclude new seating 
systems that have been built with design solutions that remove the 
unsafe condition. Zodiac Seats California recommended that we refine 
table 1 to paragraphs (c), (g), (i), (j), and (k) of the proposed AD to 
further identify part numbers by specifying the part number, and then 
use parenthetical groups in order to segregate the part numbers for the 
redesigned seating systems.
    We agree because the redesigned seating systems are not affected by 
the identified unsafe condition. The redesigned seating systems have 
new part numbers. Table 1 to paragraphs (c), (g), (i), (j), and (k) of 
the proposed AD was based upon the Zodiac Seats California technical 
standard order (TSO) authorization. We have revised table 1 to 
paragraphs (c), (g), (i), (j), and (k) of this AD by providing 
additional part number details to specify only those seats having the 
unsafe condition.
    Also, the part number format for model number 4170 in table 1 to 
paragraphs (c), (g), (i), (j), and (k) of the proposed AD has been 
revised to reflect the current format.

Request To Revise Applicability To Exclude Certain Part Numbers

    Bombardier requested that we exclude certain parts from the 
applicability of the proposed AD. Bombardier stated that seats that do 
not have meal/food trays nor upper literature pockets, such as part 
numbers 41763002-( )-( ), 41765002-( )-( ), and 41767002-( )-( ), 
should be excluded. Bombardier stated that these seats are either: (1) 
Installed at a pitch range of 41 inches to 42 inches or a pitch of 45 
inches, making it unlikely that a passenger seated behind this seat 
would be susceptible to neck injuries during forward impacts addressed 
in the proposed AD; or (2) are the last row in front of a bulkhead, and 
thus no passengers would ever impact the last row of seats when 
subjected to the forward impacts addressed in the proposed AD. 
Bombardier also recommended that the format of ``41XX( )-( )-( )'' be 
revised to ``41XXXXXXXX-( )-( ) to specify additional detail.
    We partially agree with the commenter's request. The initial 
installation controls the seating positions at a defined pitch range. 
However, table 1 to paragraphs (c), (g), (i), (j), and (k) of the 
proposed AD was established based on the TSO authorization of the 
seating systems and addresses both the initial installation and 
secondary market in which the seating system may have been modified 
after issuance of the type certificate.
    Therefore, we have revised paragraph (c) of this AD to exclude part 
numbers 41763002-( )-( ), 41765002-( )-( ), and 41767002-( )-( ), but 
only if the seats have not been modified to add a food tray or an upper 
literature pocket. We also revised the part number format in table 1 to 
paragraphs (c), (g), (i), (j), and (k) of this AD to specify additional 
detail.

Request To Revise Applicability To Exclude Certain Parts Based on 
Installation Instructions

    Zodiac Seats California requested that we exclude seats from the 
applicability of the proposed AD based on how they were originally 
installed. Zodiac Seats California stated that certain seats do not 
have the injurious condition cited in the NPRM due to how they were 
installed. Zodiac Seats California cited the following examples: Last 
row seats that do not have aft-mounted food tables; seats installed at 
pitches at 39.5 inches or greater; and seats installed at pitches 
greater than 41 inches that do not have aft-mounted food tables on the 
forward exit seat. Zodiac Seats California identified multiple part 
numbers that should be excluded.
    We do not agree. While the Zodiac Seats California ``Instructions 
for Installation and Limitations'' provides guidance for the 
installation of the seating systems, it is not mandatory that 
installers follow the guidance. The seats may be modified in the 
secondary market in which seat configurations and airplane interior 
installations may occur without Zodiac Seats California's or the 
airplane original equipment manufacturer's participation. Therefore, we 
cannot exclude seats based on the original installation. In addition, 
dynamic 16g head injury criteria (HIC) tests at a seat pitch of 39.5 
inches using the FAA 50-percentile Hybrid II Anthropomorphic Test 
Device (ATD) may lead to the conclusion that the unsafe condition does 
not exist; however, the tests do not evaluate a range of occupants. We 
have not changed this AD in this regard.

Request To Revise Applicability To Exclude Seats on The Boeing Company 
Model MD-90-30 Airplanes

    Zodiac Seats California requested that we revise the applicability 
of the proposed AD by excluding model number 4170 seats installed on 
The Boeing Company Model MD-90-30 airplanes. Zodiac Seats California 
stated

[[Page 23725]]

that the MD-90-30 installation does not require 16g row-to-row HIC 
tests because Model MD-90-30 airplanes are not required to comply with 
14 CFR 25.562(c)(5) and (c)(6). Delta Airlines (Delta) requested that 
we clarify whether the AD is applicable to Model MD-90-30 airplanes.
    We agree to clarify the applicability because seat model number 
4170 includes a group of seating systems that share a design feature 
that does not provide occupant impact protection. Known installations 
include both Model MD-90-30 and Model 717-200 airplanes. Excluding 
Model MD-90-30 airplanes would put passengers on those airplanes at 
risk for a potential serious injury. In addition, compliance with FAA 
standards that are in place at the time of certification (including 
Model MD-90-30 certification requirements) does not preclude the 
possibility that an unsafe condition will be identified in the future, 
which is the case here.
    Paragraph (c) of this AD identifies affected seating systems, which 
are installed on, but not limited to, the airplanes identified in 
paragraphs (c)(1) through (c)(9) of this AD. Although Model MD-90-30 
airplanes with affected seating systems are included in the 
applicability of this AD as a result of the phrase ``but not limited 
to,'' we have added this model to paragraph (c)(1) of this AD for 
clarification. The phrase ``but not limited to'' also covers any other 
aircraft that these seats may have been installed on via the secondary 
market, such as seats that have been excessed from one air carrier and 
put onto another airplane not identified in this AD via a supplemental 
type certificate or other installation approval method. These seating 
systems may cause serious injury to passengers during forward impacts 
when subjected to certain inertia forces; therefore, these seating 
systems are subject to the requirements of this AD.

Request To Revise Applicability To Include Components of Seating 
Systems

    United Parcel Service (UPS) requested that we revise the 
applicability of the proposed AD to include airplanes with components 
of the affected seating systems installed. UPS stated that the 
applicability of the proposed AD affects all airplanes equipped with 
the seating systems identified in paragraph (c) of the proposed AD. UPS 
added that paragraph (k) of the proposed AD has requirements that 
affect additional airplanes, and proposed that the applicability should 
specify all airplanes that may have components of the subject seat 
systems installed. Delta stated that the language in paragraph (k) of 
the proposed AD places an excessive burden on operators that may use 
components as spares on other seating systems.
    We do not agree to change the applicability of this AD in this 
regard. However, we do agree to clarify the intent of paragraph (k) of 
this AD. Paragraph (k) only applies to airplanes affected by the 
applicability specified in paragraph (c) of this AD, i.e., airplanes on 
which affected seating systems are installed. Paragraph (k) of this AD 
does not prohibit installing components on airplanes that have seating 
systems that are not included in the applicability specified in 
paragraph (c) of this AD. We have not changed this AD in this regard.

Request To Revise Applicability to Exclude Seat Systems Having Part 
Number 4157x003-( )-( )

    Embraer requested that we revise the applicability to exclude part 
number 4157x003-( )-( ). Embraer stated that part is no longer affected 
by the unsafe condition identified in the NPRM.
    We agree that part number 4157x003-( )-( ) is not affected by the 
identified unsafe condition. As stated previously, we have revised 
table 1 to paragraphs (c), (g), (i), (j), and (k) of this AD to clearly 
identify affected parts; that table does not include part number 
4157x003-( )-( ).

Request To Delay Issuance of the Proposed AD

    Austrian Airlines AG (which consists of Air Dolomiti, Austrian 
Airlines, and Lufthansa CityLine) stated that no technical option (such 
as a technical modification from Zodiac Seats California) is included 
in the proposed AD to keep the system on the airplane after the 60-
month time limit for eliminating the unsafe condition.
    We infer the commenter is requesting that we delay the proposed AD 
until a modification of affected seating systems is available. We do 
not agree with the commenter's request. We have determined that an 
unsafe condition exists and that the requirements in this AD are needed 
to address that unsafe condition. However, under the provisions of 
paragraph (l) of this AD, we will consider requests for approval of a 
modification of the seating system if sufficient data are submitted to 
substantiate that the modification would provide an acceptable level of 
safety. We have not changed this AD in this regard.

Request To Allow an Alternative Method of Compliance

    Zodiac Seats California, SkyWest Airlines, and Delta requested that 
we allow modification of the seats via a Zodiac service bulletin. 
Skywest stated that paragraph (g) of the proposed AD only allows for 
the removal of the seats. Skywest stated that if the request cannot be 
added to the proposed AD, alternative methods of compliance (AMOCs) 
will be requested to be able to use service bulletins to modify the 
seats. Delta stated that Zodiac is developing a seating system design 
that removes the unsafe condition by modifying the seats. Zodiac Seats 
California proposed to add the implementation of eight service 
bulletins as a solution to the proposed AD requirements. Zodiac Seats 
California stated it has been working with the FAA's Los Angeles ACO to 
identify a solution that can be implemented on in-service seats.
    We acknowledge the work that Zodiac Seats California has done to 
address the identified unsafe condition on the affected seating 
systems. However, Zodiac Seats California has not developed design 
solutions to correct the unsafe condition for each of the seating 
systems (all relevant service bulletins have not been issued). Once all 
the service bulletins have been issued, we can determine if they 
adequately address the identified unsafe condition. We do not consider 
that delaying this action until after the release of the manufacturer's 
planned service information is warranted, since the actions required by 
this AD adequately address the unsafe condition. However, under the 
provisions of paragraph (l) of this AD, we will consider requests for 
approval of an AMOC if sufficient data are submitted to substantiate 
that the change would provide an acceptable level of safety. We have 
not changed this AD in this regard.

Request To Extend Compliance Time

    Austrian Airlines AG requested that we allow more time for 
compliance. The commenter stated that additional time for compliance is 
needed so that suitable alternative seating systems could be procured 
and installed (i.e., time is needed for research and certification).
    We do not agree to extend the compliance time in this AD. Operators 
must comply with the actions in this AD within the compliance times 
specified in this AD in order to address the identified unsafe 
condition. The compliance times in this AD are based on the relative 
risk to safety resulting from non-compliance with 14 CFR

[[Page 23726]]

25.785 and the identified unsafe condition. However, under the 
provisions of paragraph (l) of this AD, we will consider requests for 
approval of an extension of the compliance time if sufficient data are 
submitted to substantiate that the new compliance time would provide an 
acceptable level of safety.

Request To Clarify the Determination of the Unsafe Condition for 
Previously Certified Seats

    Austrian Airlines AG stated that the proposed AD does not mention 
why the Model 4157( )-( )-( ) seats were certified on Bombardier Inc. 
Model ``CRJ 900 airplanes'' and Embraer S.A. Model ERJ 190 airplanes 
about five years ago, but now do not fulfill FAA seat certification 
requirements.
    Zodiac Seats California stated that since the seats identified in 
table 1 to paragraphs (c), (g), (i), (j), and (k) of the proposed AD 
were certified prior to the FAA accepting ``Nij < 1'' as a proposed 
means of evaluating neck injury, those seats should not be subject to 
an AD. Zodiac Seats California noted that when the regulations for HIC 
and spine loads were introduced, seats certified prior to that time 
were not required to be removed or modified.
    We infer the commenters are requesting that we clarify our 
determination of the unsafe condition on previously certificated seats. 
We agree to provide clarification. As part of seat certification 
requirements (14 CFR 21.605(a)(3), amendment 21-67, and 14 CFR 
21.603(a)(1), amendment 21-92), an applicant makes a statement of 
conformance certifying that they have met the requirements of the 
applicable regulations and that the article concerned meets the 
applicable TSO that is effective on the date the application is made. 
Complying with FAA standards that are in place at the time of 
certification does not preclude the possibility that an unsafe 
condition will be identified in the future, which is the case here. 
Therefore, we have not revised this AD in this regard.
    Regarding the use of ``Nij < 1 '' for evaluating neck injuries, the 
method was originally proposed by Zodiac Seats California in 2015 to 
define the limits of the unsafe condition, and the method was accepted 
by the FAA. In 2016, the Industry Ad Hoc Committee asked for and 
received clarification from the FAA on this method. 49 CFR 571.208 
currently defines a criterion for neck tension and compression, as well 
as a criterion that combines the effect of the neck-bending moment and 
axial force, called Nij.

Request To Revise Unsafe Condition Language

    The Industry Ad Hoc Committee and Zodiac Seats California requested 
that we revise the language for the unsafe condition in the proposed 
AD. The commenters stated that the focus should be on the injury 
mechanism that both industry and FAA find to be unacceptable (direct 
neck contact), and that we should delete the description of head motion 
and excessive neck loading. The commenters stated the Zodiac Seats 
California data do not support statements in the NPRM that refer to 
unimpeded sliding motion down the back of the seat occurring during 
testing. The commenters noted that the seats were certified according 
to certain regulations and, after a later review, the FAA determined 
that the interaction between the neck/chin and tray table was not 
acceptable. The commenters agreed that direct neck interaction and soft 
tissue contact is not acceptable. However, the commenters stated that 
Zodiac Seats California has been working to redesign and recertify some 
of the seat models.
    The commenters also expressed disagreement that to show compliance 
with 14 CFR 25.785, the ATD must demonstrate an unimpeded sliding 
motion down the back of the seat. The commenters stated that a review 
of the ATD head motion during a dynamic test is subjective and 
inaccurate, and there is no established level of performance defined in 
14 CFR 25.785 or in any other part 25 regulation with regard to sliding 
head motion or neck injury. The Industry Ad Hoc Committee referred to a 
Zodiac Seats California report that does not corroborate the statements 
specified in the proposed AD.
    The Industry Ad Hoc Committee and Zodiac Seats California stated 
that the associated criterion establishing proper evaluation to prevent 
a serious injury provided by the FAA is incomplete for validating 
airplane interior performance and practically impossible to duplicate. 
The Industry Ad Hoc Committee and Zodiac Seats California noted that 
the FAA is still actively developing and clarifying both the measuring 
techniques and requirements to support the NPRM. The Industry Ad Hoc 
Committee and Zodiac Seats California stated the rationale for the NPRM 
creates an inconsistent interpretation of 14 CFR 25.785 when it 
includes requiring an unimpeded sliding motion of the head and neck 
bending without verifying this condition does not exist across other 
seat designs. The Industry Ad Hoc Committee and Zodiac Seats California 
also asked how an applicant is expected to ensure compliance to 14 CFR 
25.785 using guidance published in Advisory Circular (AC) 25-17A 
(``Transport Airplane Cabin Interiors Crashworthiness Handbook''), May 
18, 2009, for all other areas on the seat within potential head strike 
range not specifically impacted during a 14 CFR 25.562 test event.
    We do not agree with the request to revise the unsafe condition 
language. However, we will further explain our assessment. The FAA and 
Ag[ecirc]ncia Nacional de Avia[ccedil][atilde]o Civil (ANAC) (Brazil) 
reviewed seven videos from the technical standard order authorization 
for TSO-C127a seating systems. Based on the video, the FAA 
characterized the interaction of the ATD chin and the tray table into 
five cases: two that are normal (typical) interactions, and three that 
are not. In the two typical interactions, the head either slides down 
the seat back and tray table unimpeded, or the head crushes the tray 
table inward and dislodges it downward. The FAA and Zodiac Seats 
California agreed that two of the abnormal cases are unsafe and 
corrective action is required.
    The remaining interaction involves a scenario where the bottom of 
the chin (the area closest to the face) catches the top of the tray 
table, dislodging the table downward as the head slides down the seat 
back. This condition, which was limited to seating systems with the 
marketing identification of Slim Plus, needed further investigation. On 
June 2, 2015, Zodiac Seats California proposed the pass/fail criteria 
for the investigation of those seating systems in which one or both ATD 
exhibited this interaction. In August 2015, the FAA witnessed testing 
of three seating systems at the Zodiac Seats California facility to 
evaluate this interaction. Zodiac Seats California concluded that 
design changes to the upper literature pocket and food tray table are 
necessary.
    This AD does not specify that ATD interaction between the ATD and 
seat back must be a sliding motion. The unsafe condition is based upon 
the Los Angeles ACO's review of TSO -C127, TSO-C127a, and TSO-C127b 
videos from numerous applicants (including, but not limited to, Embraer 
Aero Seating Technologies, Recaro, and TIMCO) for seating systems. The 
Zodiac Seats California design is such that a new potential injury to 
the occupant is introduced with neck/chin interaction. Zodiac Seats 
California proposed a method of compliance to quantify the injury for 
these seating systems (including the use of Nij), and the FAA found the 
methodology to be acceptable. However, compliance with Nij is not being 
required by this AD.

[[Page 23727]]

    Regarding the requests to revise the unsafe condition description, 
this information was included in the Discussion section of the NPRM, 
which is not restated in this final rule. Therefore, there is no need 
to revise this final rule in this regard.

Request To Clarify the Determination of Unsafe Condition

    The Industry Ad Hoc Committee and Zodiac Seats California stated 
the NPRM was initiated with inconclusive data, creating a non-standard 
approach within industry based on a number of unanswered questions. The 
commenters requested clarification of how the unsafe condition was 
determined. The commenters questioned if the FAA has determined that an 
``unimpeded sliding motion'' and/or Nij is the right criteria for 
evaluating neck injury in aircraft interiors.
    The Industry Ad Hoc Committee and Zodiac Seats California also 
stated that evaluation of potential neck injury severity by reviewing 
test videos of the Hybrid II ATD head motion along the seat back 
surface is inaccurate and subjective. The Industry Ad Hoc Committee and 
Zodiac Seats California reiterated that it is not possible to determine 
the extent of neck bending loads leading to neck injury by video 
evaluation only. The Industry Ad Hoc Committee and Zodiac Seats 
California stated that any new regulatory performance criteria defined 
by the FAA must be developed through comprehensive research to assess 
validity, repeatability, and feasibility. The Industry Ad Hoc Committee 
concluded that the FAA should establish appropriate injury criteria 
with FAA research data, follow the proper rulemaking process, and 
perform a cost benefit analysis of new regulations on type certificate/
supplemental type certificate projects. The Industry Ad Hoc Committee 
requested that FAA continue research with the FAA Hybrid III ATD and 
fully substantiate Nij pass/fail criteria before establishing a 
threshold of Nij < 1 and associated force/moment limits for row-to-row 
dynamic impact tests, which forces the industry to a more conservative 
value than necessary. The Industry Ad Hoc Committee noted the seat 
supplier community has already attempted to clarify and mitigate the 
FAA's concerns and has offered a more specific evaluation method.
    Delta suggested that further testing and industry discussion should 
take place prior to any rulemaking that would allow inclusion of 
National Highway Traffic Safety Administration (NHTSA) neck criteria 
and potential neck interactions into injury testing requirements to 
comply with 14 CFR 25.785.
    We agree to clarify our determination of the unsafe condition. No 
new criteria have been established by the FAA. However Zodiac Seats 
California has proposed, and the FAA accepted, criteria that 
substantiated the unsafe condition. The use of Nij has been volunteered 
and accepted as one means of demonstrating compliance to 14 CFR 25.785.
    The FAA reviewed screen captures when Zodiac Seats California 
approached the FAA with a concern of the ATD and seat back interaction. 
The FAA advised Zodiac Seats California to revise the design to address 
the interaction. We acknowledge that loads and injury cannot be 
evaluated by video only and note that Zodiac Seats California proposed 
criteria that included neck bending loads to determine whether the FAA 
concern about injuries was substantiated. The potential for injury was 
quantified and substantiated.
    We do not agree that additional research is necessary to establish 
the human tolerance for neck injuries. The Nij, as implemented by 
NHTSA, was specifically intended to evaluate an injurious combined 
tension/extension loading condition that can be created by airbag 
interaction or when the ATD chin hangs up on a protruding seat back 
feature (e.g., downward sliding is arrested, chin catches, hangs or 
impedes with a tray ledge or other seat feature).
    Therefore, the FAA finds that when a quantitative assessment is 
necessary, the NHTSA Nij and load limit criteria are well-suited to 
assessing the injury potential of seat back interactions and airbag/
wall interactions. We have not changed this AD in this regard.

Request To Clarify the Determination of the Injury Criteria and the 
Effect on the Regulations

    Delta requested that we provide additional details on the relevant 
information evaluated for this NPRM. Delta asked that we further define 
the testing and findings that were used to determine new injury 
mechanisms and neck bending loads that were found to contribute to the 
unsafe condition on previously approved seats. Delta also requested 
confirmation that the NPRM does not formalize the FAA's position that 
new neck injury mechanisms should be included in injury criteria 
requirements of 14 CFR 25.785. Delta also requested that we confirm 
that the NPRM does not redefine or add requirements to 14 CFR 25.785. 
Delta stated that Nij < 1 is not injury criteria under 14 CFR 25.562 or 
14 CFR 25.785.
    We agree to provide clarification. This AD does not redefine or add 
requirements to 14 CFR 25.785. However, new seating system designs are 
introducing new serious injury mechanisms that are considered unsafe 
conditions. When the new injury mechanisms are observed, it is up to 
industry to identify them as injurious even when criteria to define 
them may not exist, and to develop safety features that minimize those 
injuries or remove the injury mechanisms. This AD does not impose, nor 
does it identify, new criteria to quantify such injury mechanisms.
    However, if a test method would be proposed to quantify the injury 
in an AMOC, we would review the AMOC proposal for corrective action to 
these seating systems. The use of Nij and its tension, compression, 
flexion, extension, rotation, neck impact, and chin-concentrated 
loading is one method of showing the system is not injurious. This AD 
does not mandate using particular criteria; however, the use of Nij was 
a method proposed by Zodiac Seats California and found acceptable by 
the FAA.

Request To Revise the Parts Installation Limitations and Prohibition

    Bombardier, Embraer, and Zodiac Seats California requested that we 
delay the implementation of paragraph (i) of the proposed AD, ``Parts 
Installation Limitations: Seating Systems.'' Embraer also requested 
that we delay the implementation of paragraph (k) of the proposed AD, 
``Parts Installation Prohibition: Components of Seating Systems.'' 
Bombardier requested that we change ``As of the effective date of this 
AD, no person may install . . .'' in paragraph (i) of the proposed AD 
to a date that would be approximately six months after the effective 
date of the AD. Zodiac Seats California requested that we allow 
installation of seats, except for part numbers 4157( )-( )-( ) and 
4175( )-( )-( ), to be installed for several months after the effective 
date of the AD.
    Bombardier stated that it currently deliveries Model CRJ900 and 
Q400 airplanes that have the affected seats to operators outside of the 
United States. Bombardier noted that Transport Canada Civil Aviation 
(TCCA) has stated it will adopt the FAA's AD immediately and added that 
Zodiac Seats California has not certified alternative seats. Bombardier 
stated that since operators will refuse delivery of airplanes without 
seats, it requests delaying the effective date of paragraph

[[Page 23728]]

(i) of the proposed AD. Bombardier stated that additional time is 
necessary to completely assess the situation and provide a suitable 
plan in order to not affect future production deliveries.
    Embraer requested that we revise paragraph (i) of the proposed AD, 
as well as paragraph (k) of the proposed AD, to allow certain defined 
part numbers to be installed on newly manufactured aircraft beyond the 
effective date. Embraer stated that paragraph (i) of the proposed AD 
will effectively stop deliveries of Model ERJ 170 and ERJ 190 
airplanes. Embraer stated no other seat replacements are currently 
available and, therefore, the proposed AD would affect the delivery of 
16 airplanes from Embraer to the United States. Embraer stated that the 
proposed change would result in a negligible increase in the number of 
seats affected by the proposed AD.
    We disagree with the commenters' requests. Zodiac Seats California 
has confirmed that affected seats are not being delivered to aircraft 
manufacturers and only seats with a new design (i.e., seats that are 
not affected by this AD) are being delivered. Therefore, production 
delivery of aircraft should not be impacted. Operators that receive 
aircraft with the affected seats have the compliance time of 60 months 
to comply with this AD.
    We have determined that this AD should prohibit installation of the 
unsafe parts as of the effective date of this AD, except under certain 
conditions, as specified in paragraphs (i)(1) and (i)(2) of this AD. We 
have not changed this AD in this regard. However, under the provisions 
of paragraph (l) of this AD, we will consider requests for approval of 
an extension of the compliance times for parts installations if 
sufficient data are submitted to substantiate that the change would 
provide an acceptable level of safety.

Request To Revise the Parts Installation Provisions

    Skywest Airlines requested that we change the text in the parts 
installation provisions of paragraph (j) of the proposed AD from `` . . 
. other than those installed as direct spares, . . . '' to `` . . . 
other than those installed as direct spares, or on production aircraft, 
. . . .'' The commenter stated that paragraphs (i) and (j) of the 
proposed AD do not adequately address the installation of affected 
seats on newly built airplanes.
    We do not agree with the request to allow the installation of known 
affected seating systems on production airplanes. The intent of 
paragraphs (i) and (j) of this AD is to limit the introduction of known 
unsafe parts in the worldwide fleet. Granting the request would 
increase the population of seating systems that may cause serious 
injury to the occupant during forward impacts when subjected to certain 
inertia forces. We have not revised this AD in this regard.

Request To Clarify Prohibition of Components

    Two commenters requested that we revise paragraph (k) of the 
proposed AD. Delta requested that we revise paragraph (k) of the 
proposed AD to prohibit only seat system components that directly 
contribute to the unsafe condition identified in the proposed AD. Delta 
stated that there are various components, such as cushions, seat 
covers, etc., that are not related to the unsafe condition.
    UPS stated that the description of ``component'' is too generic. 
UPS stated it does not think the intent is to limit the installation of 
a certain restraint system, or even a bolt, on all airplanes because 
the part was installed on an affected seating system. UPS stated the 
proposed AD should identify specific parts that are prohibited from 
use.
    We agree to clarify the prohibited components. There are items such 
as the seat cushions, seat pans, restraint systems, and track fittings 
that are not critical components of the injurious mechanism. We have 
revised paragraph (k) of this AD by replacing the text ``any 
component'' with ``components critical to the unsafe condition 
mechanism.'' We have also added a sentence to the introductory text of 
paragraph (k) of this AD to specify that components critical to the 
unsafe condition mechanism are identified as the seat back assembly, 
including food tray assembly, food tray latch, food tray arms, 
hydraulic seat lock (hydrolock), and energy absorbing system.

Request To Revise Cost

    Multiple commenters (SkyWest Airlines, UBS Equity Research--
Aerospace and Defence, Bombardier, Austrian Airlines AG, Delta, Zodiac 
Seats California, and the Industry Ad Hoc Committee) requested that we 
clarify or increase the cost estimate. UBS Equity Research--Aerospace 
and Defence asked if the cost of seat modification is estimated to be 
$85 per seat or whether a replacement is necessary. Multiple commenters 
asked that the cost analysis include the costs to procure replacement 
seats; several commenters specified research costs, development costs, 
engineering certification costs, and the cost of seat replacement. The 
commenters also asked us to account for loss of revenue; several 
commenters noted that commercial airplanes cannot be operated for their 
intended purpose without seats installed. Skywest Airlines noted that 
the cost of replacement seats is estimated to be between $250,000 and 
$500,000 for the affected seats in one airplane. Bombardier suggested 
adding 2 work-hours for procuring and reinstalling alternate certified 
seats.
    We do not agree to revise the costs specified in this AD. We have 
included the estimated cost of the actions required by this AD, which 
is applicable to the U.S. fleet. This AD requires removal of non-
compliant seats, and we have included the costs for that action. 
Removing non-compliant seats addresses the unsafe condition and 
restores compliance to the airworthiness regulations.
    While this AD does not require modifying or replacing seats, we 
recognize that operators could choose to replace non-compliant seating 
systems or modify affected seats. However, we are unable to make a 
reasonable assessment of how many seats would be required to be 
replaced or to assess the cost of modifying affected seats. 
Modifications would need to be approved as an AMOC in accordance the 
procedures specified in paragraph (l) of this AD. We also acknowledge 
that, for operators that remove non-compliant seats, there could a loss 
of revenue.
    We also do not consider it appropriate to attribute the costs 
associated with airplane ``down time'' to an AD. Normally, compliance 
with an AD will not necessitate any additional down time beyond that of 
a regularly scheduled maintenance hold. Even if additional down time is 
necessary for some airplanes in some cases, we do not have sufficient 
information to evaluate the number of airplanes that may be affected or 
the amount of additional down time that may be required. Therefore, 
attempting to estimate such costs is impractical. We have not revised 
this AD in this regard.

Request To Clarify ``Vague'' Terminology

    The Industry Ad Hoc Committee and Zodiac Seats California stated 
that the proposed AD used subjective and ``vague'' terms such as 
``catch'' and ``unimpeded sliding motion down.'' The Industry Ad Hoc 
Committee requested that the FAA work with industry to develop 
additional research and avoid these terms. The Industry Ad Hoc 
Committee suggested terms such as

[[Page 23729]]

``directly impedes the head's downward sliding motion'' and ``chin 
hang-up.''
    We agree to provide further clarification. Our review of 
certification testing has shown that in dynamic seat tests, impact of 
an ATD head onto a typical transport passenger seat back normally 
results in an initial head strike followed by an unimpeded sliding 
motion down the back of the seat. In addition, as stated in the 
Discussion section of the NPRM, the design of the affected seating 
systems introduced new injury mechanisms, such that the chin can 
``catch'' on the seats, causing high neck bending loads and direct 
concentrated loading on the neck. We have not changed this AD in this 
regard.

Request for Collaborative Research

    Boeing recommended an all-inclusive, industry-wide research and 
data analysis evaluation to develop a common and measurable standard 
with acceptable limitations for any new requirement such as neck injury 
criteria. Boeing stated it welcomes a collaborative research approach 
with the FAA and industry partners to develop appropriate neck injury 
criteria for aircraft seats prior to any rulemaking activity.
    We agree that a collaborative research approach is beneficial. As 
early as October 2007, during the Fifth Triennial International 
Aviation Fire and Cabin Safety Research Conference, industry was 
notified of the potential for seat back interaction to produce high 
neck loads. The data available at that time, however, did not indicate 
that neck injury was a significant risk in most of the forward facing 
configurations tested.
    An example of this specific type of injury was brought to industry 
attention during The Seventh Triennial International Fire & Cabin 
Safety Research Conference in December 2013. The FAA welcomes 
additional research, as appropriate, and the development of appropriate 
neck injury criteria for aircraft seats.

Conclusion

    We reviewed the relevant data, considered the comments received, 
and determined that air safety and the public interest require adopting 
this AD with the changes described previously and minor editorial 
changes. We have determined that these minor changes:
     Are consistent with the intent that was proposed in the 
NPRM for correcting the unsafe condition; and
     Do not add any additional burden upon the public than was 
already proposed in the NPRM.
    We also determined that these changes will not increase the 
economic burden on any operator or increase the scope of this AD.

Costs of Compliance

    We estimate that this AD affects 10,482 seating systems installed 
on, but not limited to, various transport category airplanes of U.S. 
registry.
    We estimate the following costs to comply with this AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Removal...............................  1 work-hour x $85 per                 $0             $85        $890,970
                                         hour = $85.
----------------------------------------------------------------------------------------------------------------

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of the FAA Administrator. Subtitle VII: Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701: ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    This AD will not have federalism implications under Executive Order 
13132. This AD will not have a substantial direct effect on the States, 
on the relationship between the national government and the States, or 
on the distribution of power and responsibilities among the various 
levels of government.
    For the reasons discussed above, I certify that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979),
    (3) Will not affect intrastate aviation in Alaska, and
    (4) Will not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.

Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive (AD):

2017-09-09 Zodiac Seats California LLC: Amendment 39-18871; Docket 
No. FAA-2016-5595; Directorate Identifier 2015-NM-087-AD.

(a) Effective Date

    This AD is effective June 28, 2017.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to Zodiac Seats California LLC seating systems 
having the model numbers and part numbers identified in table 1 to 
paragraphs (c), (g), (i), (j), and (k) of this AD, as installed on, 
but not limited to, the airplanes identified in paragraphs (c)(1) 
through (c)(9) of this AD; all type certificated models in any 
category; except that model number 4157 seating systems having part 
numbers 41763002-( )-( ), 41765002-( )-( ), and 41767002-( )-( ) 
that have not been modified to add a food tray or an upper 
literature pocket are not affected by this AD. If any model number 
4157 having part number 41763002-( )-( ), 41765002-( )-( ), or 
41767002-( )-( ) is modified to add a food tray or an upper 
literature pocket, the requirements of this AD apply.
    (1) The Boeing Company Model 717-200 airplanes and Model MD-90-
30 airplanes.

[[Page 23730]]

    (2) Bombardier, Inc. Model CL-600-2C10 (Regional Jet Series 700, 
701, & 702) airplanes.
    (3) Bombardier, Inc. Model CL-600-2D24 (Regional Jet Series 900) 
airplanes.
    (4) Bombardier, Inc. Model DHC-8-400, -401, and -402 airplanes.
    (5) Empresa Brasileira de Aeronautica S.A. (Embraer) Model EMB-
145XR airplanes.
    (6) Embraer S.A. Model ERJ 170-100 LR airplanes.
    (7) Embraer S.A. Model ERJ 170-200 LR, and -200 STD airplanes.
    (8) Embraer S.A. Model ERJ 190-100 STD, -100 LR, and -100 IGW 
airplanes.
    (9) Embraer S.A. Model ERJ 190-200 LR airplanes.

 Table 1 to Paragraphs (c), (g), (i), (j), and (k) of This AD--Affected
                             Seating Systems
------------------------------------------------------------------------
                                Part No. (where x
           Model No.             = 2, 3, 4, 5, 6,       Description
                                      or 7)
------------------------------------------------------------------------
4157..........................  4157x001-( )-( ).  Double Seat Assembly
                                                    System.
4157..........................  4157x002-( )-( ).  Double Seat Assembly
                                                    System.
4157..........................  4158x001-( )-( ).  Double Seat Assembly
                                                    System.
4157..........................  4158x002-( )-( ).  Double Seat Assembly
                                                    System.
4157..........................  4175x001-( )-( ).  Double Seat Assembly
                                                    System.
4157..........................  4175x002-( )-( ).  Double Seat Assembly
                                                    System.
4157..........................  4176x001-( )-( ).  Double Seat Assembly
                                                    System.
4157..........................  4176x002-( )-( ).  Double Seat Assembly
                                                    System.
4157..........................  4177x001-( )-( ).  Double Seat Assembly
                                                    System.
4157..........................  4177x002-( )-( ).  Double Seat Assembly
                                                    System.
4157..........................  4178x001-( )-( ).  Double Seat Assembly
                                                    System.
4157..........................  4178x002-( )-( ).  Double Seat Assembly
                                                    System.
4170..........................  4169x001-( )-( ).  Double Seat Assembly
                                                    System.
4170..........................  4170x001-( )-( ).  Triple Seat Assembly
                                                    System.
4170..........................  4171x001-( )-( ).  Single Seat Assembly
                                                    System Exit Row.
4170..........................  4172x001-( )-( ).  Double Seat Assembly
                                                    System Exit Row.
4184..........................  4184x002-( )-( ).  Double Seat Assembly
                                                    System.
------------------------------------------------------------------------

(d) Subject

    Air Transport Association (ATA) of America Code 2520, Passenger 
Compartment Equipment.

(e) Unsafe Condition

    This AD was prompted by a determination that the affected 
seating systems may cause serious injury to the occupant during 
forward impacts when subjected to certain inertia forces. We are 
issuing this AD to prevent serious injury to the occupant during 
forward impacts in emergency landing conditions.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Seating System Removal

    Within 60 months after the effective date of this AD, remove all 
seating systems having a model number and part number identified in 
table 1 to paragraphs (c), (g), (i), (j), and (k) of this AD.

(h) Definition of a ``Direct'' Spare

    For the purposes of this AD, a ``direct'' spare has the same 
part number as the part it replaces.

(i) Parts Installation Limitations: Seating Systems

    As of the effective date of this AD, no person may install on 
any airplane any Zodiac Seats California LLC seating systems having 
any model number and part number identified in table 1 to paragraphs 
(c), (g), (i), (j), and (k) of this AD that are approved under 
technical standard order (TSO) TSO-C127a; except as specified in 
paragraphs (i)(1) and (i)(2) of this AD.
    (1) Seating systems may be removed from service for the purpose 
of performing maintenance activities and reinstalled on airplanes 
operated by the same operator, but only until the operator complies 
with the removal of affected seating systems required by paragraph 
(g) of this AD.
    (2) New seating systems may be installed as direct spares for 
the same part number seating systems, but only until the operator 
complies with the removal of affected seating systems required by 
paragraph (g) of this AD. Seating systems installed as direct spares 
are subject to the applicable requirements and compliance times 
specified in this AD.

(j) Parts Installation Provisions: Installation and Rearrangement

    Installation of a seating system having any model number and 
part number identified in table 1 to paragraphs (c), (g), (i), (j), 
and (k) of this AD, other than those installed as direct spares, is 
considered a new installation that needs approval; except that re-
arrangement of the existing installed seating systems on an airplane 
is acceptable until the operator complies with the removal of 
affected seating systems required by paragraph (g) of this AD, 
provided the re-arrangement follows the same installation 
instructions and limitations as the original certification (e.g., if 
the original limitations allowed 32-inch to 34-inch pitch, the new 
layout must be pitched within that range).

(k) Parts Installation Prohibition: Components of Seating Systems

    As of the effective date of this AD, no person may install, on 
any airplane, any component critical to the unsafe condition 
mechanism of any seating system having any model number identified 
in table 1 to paragraphs (c), (g), (i), (j), and (k) of this AD that 
is approved under TSO-C127a; except as specified in paragraphs 
(k)(1), (k)(2), and (k)(3) of this AD. Components critical to the 
unsafe condition mechanism are identified as the seat back assembly, 
including food tray assembly, food tray latch, food tray arms, 
hydraulic seat lock (hydrolock), and energy absorbing system.
    (1) Components critical to the unsafe condition mechanism of 
seating systems specified in paragraph (g) of this AD may be removed 
from service and re-installed on airplanes operated by the same 
operator, but only until the operator complies with the removal of 
affected seating systems required by paragraph (g) of this AD.
    (2) New components critical to the unsafe condition mechanism of 
seating systems may be installed as direct spares for the same part 
number components, but only until the operator complies with the 
removal of affected seating systems required by paragraph (g) of 
this AD.
    (3) Components critical to the unsafe condition mechanism of 
seating systems specified in paragraph (g) of this AD that are 
installed as direct spares are subject to the applicable 
requirements and compliance times specified in paragraph (g) of this 
AD.

(l) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Los Angeles Aircraft Certification Office 
(ACO), FAA, has the authority to approve AMOCs for this AD, if 
requested using the procedures found in 14 CFR 39.19. In accordance 
with 14 CFR 39.19, send your request to your principal inspector or 
local Flight Standards District Office, as appropriate. If sending 
information directly to the manager of the ACO, send it to the 
attention of the person identified in paragraph (m) of this AD. 
Information may be emailed to: 9-ANM-LAACO-AMOC-Requests@faa.gov.
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district office.

[[Page 23731]]

(m) Related Information

    For more information about this AD, contact Patrick Farina, 
Aerospace Engineer, Cabin Safety Branch, ANM-150L, FAA, Los Angeles 
ACO, 3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: 562-
627-5344; fax: 562-627-5210; email: patrick.farina@faa.gov.

(n) Material Incorporated by Reference

    None.

    Issued in Renton, Washington, on April 27, 2017.
Paul Bernado,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2017-10256 Filed 5-23-17; 8:45 am]
BILLING CODE 4910-13-P