DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0106; Project Identifier AD-2020-00708-R]
RIN 2120-AA64

Airworthiness Directives; Sikorsky Aircraft Corporation Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD)
for Sikorsky Aircraft Corporation (Sikorsky) Model S-92A helicopters.
This proposed AD was prompted by an incident of a side facing utility
seat detaching from wall attachment points. This proposed AD would
require modifying certain side facing utility seats and observer seats.
This proposed AD would also prohibit installing those seats unless the
modification has been accomplished. The FAA is proposing this AD to
address the unsafe condition on these products.

DATES: The FAA must receive comments on this proposed AD by April 19,
2021.

ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:

Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow the
instructions for submitting comments.

Fax: (202) 493-2251.

Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE, Washington, DC 20590.

Hand Delivery: Deliver to Mail address above between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this NPRM, contact your local
Sikorsky Field Representative or Sikorsky's Service Engineering Group
at Sikorsky Aircraft Corporation, Mailstop K100, 124 Quarry Road,
Trumbull, CT 06611; telephone 1-800-946-4337 (1-800-Winged-S); email
wcs_cust_service_eng.gr-sik@lmco.com. Operators may also log on to the
Sikorsky 360 website at https://www.sikorsky360.com. You may view this
service information at the FAA, Office of the Regional Counsel,
Southwest Region, 10101 Hillwood Pkwy., Room 6N-321, Fort Worth, TX
76177. For information on the availability of this material at the FAA,
call (817) 222-5110.

Examining the AD Docket

You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2021-0106; or in person at
Docket Operations between 9 a.m. and 5 p.m., Monday through Friday,
except Federal holidays. The AD docket contains this NPRM, any comments
received, and other information. The street address for Docket
Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Dorie Resnik, Aerospace Engineer,
Aviation Safety Section, Boston ACO Branch, FAA, 1200 District Ave.,
Burlington, MA 01803; phone: (781) 238-7693; email:
dorie.resnik@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites you to send any written relevant data, views, or
arguments about this proposal. Send your comments to an address listed
under ADDRESSES. Include "Docket No. FAA-2021-0106; Project Identifier
AD-2020-00708-R" at the beginning of your comments. The most helpful
comments reference a specific portion of the proposal, explain the
reason for any recommended change, and include supporting data. The FAA
will consider all comments received by the closing date and may amend
this proposal because of those comments.

Except for Confidential Business Information (CBI) as described in
the following paragraph, and other information as described in 14 CFR
11.35, the FAA will post all comments received, without change, to
https://www.regulations.gov, including any personal information you
provide. The agency will also post a report summarizing each
substantive verbal contact received about this NPRM.

Confidential Business Information

CBI is commercial or financial information that is both customarily
and actually treated as private by its owner. Under the Freedom of
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public
disclosure. If your comments responsive to this NPRM contain commercial
or financial information that is customarily treated as private, that
you actually treat as private, and that is relevant or responsive to
this NPRM, it is important that you clearly designate the submitted
comments as CBI. Please mark each page of your submission containing
CBI as "PROPIN." The FAA will treat such marked submissions as
confidential under the FOIA, and they will not be placed in the public
docket of this NPRM. Submissions containing CBI should be sent to Dorie
Resnik, Aerospace Engineer, Aviation Safety Section, Boston ACO Branch,
FAA, 1200 District Ave., Burlington, MA 01803; phone: (781) 238-7693;
email: dorie.resnik@faa.gov. Any commentary that the FAA receives which
is not specifically designated as CBI will be placed in the public
docket for this rulemaking.

Background

The FAA proposes to adopt a new AD for Sikorsky Model S-92A
helicopters with certain Martin-Baker side facing utility seats and
observer seats installed. This proposed AD was prompted by an incident
of a side facing utility seat detaching from wall attachment points
during dynamic testing. The root cause has been identified as a change
in the finishing process of the main back tube. Due to design
similarity, certain observer seats are also subject to this unsafe
condition.

Accordingly, this proposed AD would require replacing the main back
tube assembly in affected side facing utility seats and observer seats.
This proposed AD would also prohibit installing those seats unless the
main back tube assembly has been replaced. This condition, if not
addressed, could result in increased surface friction in the direction
of the seat attenuation, failure of proper utility seat attenuation
during a crash event, excessive lumbar loads in an observer seat during
a crash event, and subsequent excessive or fatal occupant injury.

FAA's Determination

The FAA is issuing this NPRM after determining that the unsafe
condition described previously is likely to exist or develop on other
products of the same type design.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Martin-Baker Special Information Leaflet (SIL) No.
831, dated July 10, 2019 (SIL 831), for side facing utility seat
supplier part number (P/N) MBCS12410AA001, and Martin-Baker SIL No.
833, dated July 11, 2019 (SIL 833), for observer seat supplier P/N
MBCS12200 and MBCS7301-2. This service information specifies procedures
for disassembling the seat, inspecting components, replacing the main
back tube assembly (tube assembly, back main), and reassembling,
testing, and marking the seat. SIL 831 and SIL 833 are attached to
Sikorsky S-92A Helicopter Alert Service Bulletin 92-25-026, dated March
5, 2020 (ASB 92-25-026).

The FAA also reviewed ASB 92-25-026, which specifies procedures for
preparing the helicopter for replacing the main back tube assembly by
following SIL 831 or SIL 833, as applicable to your seat. This service
information specifies removing existing placards, complying with the
applicable SIL, reinstalling the removed placards, inspecting for
foreign object debris (FOD), and cleaning.

This service information is reasonably available because the
interested parties have access to it through their normal course of
business or by the means identified in ADDRESSES.

Proposed AD Requirements in This NPRM

This proposed AD would require, within 125 hours time-in-service
(TIS) or six months after the effective date of this AD, whichever
occurs first, removing certain placards, accomplishing the actions
specified in SIL 831 or SIL 833 already described, and reinstalling the
previously removed placards.

Differences Between This Proposed AD and the Service Information

ASB 92-25-026 specifies a compliance time of no later than March 5,
2021; where this proposed AD specifies a compliance time of within 125
hours TIS or six months after the effective date of this AD, whichever
occurs first. ASB 92-25-026 specifies inspecting for FOD and cleaning;
whereas this proposed AD does not. SIL 831 and SIL 833 specify
destroying and disposing removed main back tube assemblies and
discarding removed split pins and tie down straps; whereas this
proposed AD would require removing those parts from service instead.
The service information specifies recording compliance; whereas this
proposed AD does not.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 9 helicopters of U.S. Registry. Labor rates are estimated at $85
per work-hour. Based on these numbers, the FAA estimates the following
costs to comply with this proposed AD.

Replacing a main back tube assembly would take about 2 work-hours
and parts would cost about $11,217, for an estimated cost of about
$11,387 per seat. Each helicopter could have up to 19 affected seats,
which would take up to 38 work-hours and parts would cost up to about
$213,123, for an estimated cost of up to about $216,353 per helicopter
and $1,947,177 for the U.S. fleet.

The FAA has included all known costs in its cost estimate.
According to the manufacturer, however, some of the costs of this
proposed AD may be covered under warranty, thereby reducing the cost
impact on affected operators.

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.

The FAA is 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

The FAA determined that this proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD would 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 this proposed
regulation:

(1) Is not a "significant regulatory action" under Executive
Order 12866,

(2) Would not affect intrastate aviation in Alaska, and

(3) Would 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.

The Proposed Amendment

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

PART 39--AIRWORTHINESS DIRECTIVES

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]

2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive: