DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2016-8501; Product Identifier 2014-SW-042-AD]
RIN 2120-AA64

Airworthiness Directives; Sikorsky Aircraft Corporation
Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Supplemental notice of proposed rulemaking (SNPRM); reopening
of comment period.

-----------------------------------------------------------------------

SUMMARY: We are revising an earlier proposal for Sikorsky Aircraft
Corporation (Sikorsky) Model S-92A helicopters. This action revises the
notice of proposed rulemaking (NPRM) by increasing the estimated costs
of compliance and removing the daily inspection requirements. We are
proposing this airworthiness directive (AD) to address the unsafe
condition on these products. Since these actions would impose an
additional economic burden over that proposed in the NPRM, we are
reopening the comment period to allow the public the chance to comment
on this change.

DATES: The comment period for the NPRM published in the Federal
Register on July 15, 2016 (81 FR 46002), is reopened.

We must receive comments on this SNPRM by February 11, 2019.

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 http://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: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE, Washington, DC 20590, between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays.

For service information identified in this SNPRM, contact Sikorsky
Aircraft Corporation, Customer Service Engineering, 124 Quarry Road,
Trumbull, CT 06611; telephone 1-800-Winged-S or 203-416-4299; email:
wcs_cust_service_eng.gr-sik@lmco.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.

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-2016-8501;
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 SNPRM, the regulatory evaluation, any comments received, and other
information. The street address for Docket Operations (phone: 800-647-
5527) is in the ADDRESSES section. Comments will be available in the AD
docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Kristopher Greer, Aviation Safety
Engineer, Boston ACO Branch, Compliance and Airworthiness Division,
1200 District Avenue, Burlington, Massachusetts 01803; telephone (781)
238-7799; email Kristopher.Greer@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or
arguments about this proposal. Send your comments to an address listed
under the ADDRESSES section. Include "Docket No. FAA-2016-8501;
Product Identifier 2014-SW-042-AD" at the beginning of your comments.
We specifically invite comments on the overall regulatory, economic,
environmental, and energy aspects of this SNPRM. We will consider all
comments received by the closing date and may amend this SNPRM because
of those comments.

We will post all comments we receive, without change, to http://www.
regulations.gov, including any personal information you provide. We
will also post a report summarizing each substantive verbal contact we
receive about this SNPRM.

Discussion

We issued an NPRM to amend 14 CFR part 39 by adding an AD that
would apply to Sikorsky Model S-92A helicopters with certain part-
numbered frame assemblies installed. The NPRM published in the Federal
Register on July 15, 2016 (81 FR 46002). The NPRM was prompted by
fatigue analysis indicating the possible development of stress
concentrations at the steel doublers on the main transmission airframe
support structure top deck, as well as the discovery of a helicopter
with a crack in the STA 362 frame and skin. The NPRM proposed to
require inspecting the main transmission forward and aft frame
assemblies and adjacent skins for a crack and loose fasteners and
replacing or repairing any cracked part or loose fastener. The NPRM
also proposed to require establishing life limits for certain frame
assemblies. The proposed requirements were intended to detect a crack
in a frame assembly and prevent failure of a frame and subsequent loss
of control of the helicopter.

Actions Since the NPRM Was Issued

Since we issued the NPRM, we have revised the number of work-hours
to replace the aircraft frames based upon the comments we received.
This resulted in an overall increase in the cost of complying with the
proposed AD. Since the economic burden is higher than that in the NPRM,
we are reopening the comment period to allow the public the chance to
comment on this new estimate.

Comments

We gave the public the opportunity to comment on the NPRM. After
our NPRM was published, we received the following comments from
Sikorsky.

Request To Require Modification of the Frame Assembly

Sikorsky requested that the AD require altering the transmission
support frames in accordance with Sikorsky S-92 Alert Service Bulletin
92-53-012, Basic Issue, dated February 10, 2014 (ASB 92-53-012), and
Sikorsky Special Service Instructions No. 92-074-E, Revision E, dated
April 9, 2014 (SSI 92-074-E). In support of its request, Sikorsky
stated this modification largely improves the fatigue capability of the
transmission support frames. Sikorsky also requested updating language
in the preamble to reflect requiring the modification.

We disagree. We determined that the alterations to the transmission
support frames are not required to correct the unsafe condition.

Request To Remove the Daily Inspection

Sikorsky requested that we remove the daily repetitive inspection
requirement from the proposed AD. In support of this request, Sikorsky
stated that the proposed AD's requirement to perform this same
inspection every 150 hours time-in-service (TIS) would maintain the
safety of the aircraft. Sikorsky further stated structural analysis
reports substantiate the 150-hour inspection interval.

We agree that the daily inspection requirement is not necessary to
maintain the fleet's airworthiness. After reviewing data from
Sikorsky's organization designation authorization supporting its life
limit and continuing airworthiness projects, we determined that
repeating the inspections every 150 hours would be adequate to detect
and prevent an unsafe condition.

Request That the AD Reference the Maintenance Manual

Sikorsky requested that the proposed AD reference the main
transmission support structure inspection task in the Sikorsky
maintenance manual for the 150-hour repetitive inspection. In support
of this request, Sikorsky stated this task provides a complete,
detailed procedure for the inspection requirements.

We agree. We have revised the proposed AD to reference the task
card as guidance for the 150-hour inspection.

Request To Delay Issuance of the Proposed AD

Sikorsky requested that we delay issuing this proposed AD until
after Sikorsky completes a project to increase the life limits of the
forward STA 382 and aft STA 362 frame assemblies.

We disagree. Because this unsafe condition could exist or develop
on Sikorsky Model S-92A helicopters, the proposed actions are necessary
to ensure safety of the U.S. fleet. Issuance of an AD is the
appropriate method to correct the unsafe condition. Should completion
of Sikorsky's certification project result in a corrective action that
removes the unsafe condition, we might consider further rulemaking
action.

Request To Correct Part Numbers

Sikorsky requested that we correct two part numbers in Table 4 of
the Required Actions. Specifically, Sikorsky stated part number "92070-
02108-042" should be "92209-02108-042" and part number "92080-02108-103"
should be "92209-02108-103."

We agree. We have revised the table accordingly.

Request To Add Serial Numbers to the Applicability

Sikorsky requested that the proposed life limits only apply to
helicopters with serial numbers 920006 through 920243. In support of
this request, Sikorsky advised that starting with serial number 920244,
helicopters were manufactured with an upgraded titanium frame
configuration that is not affected by the proposed AD.

We disagree. While production helicopters starting with serial
number 920244 may not currently have the parts that are subject to the
unsafe condition installed, operators are not required to maintain that
configuration. Omitting the serial numbers allows the proposed AD to
apply to any Model S-92A helicopter if a frame subject to the unsafe
condition is later installed.

Request To Clarify Language Regarding Life Limit of Altered Parts

Sikorsky requested that we clarify the wording of the 28,500-hour
life limit for parts that are altered and changed to a new part number.
Specifically, Sikorsky requested that we change "28,500 hours TIS
total (regardless of P/N)" to "28,500 hours TIS total from the
original frame part number initial service date."

We disagree. The language in the proposed AD clearly states that
this life limit applies regardless of whether the frame assembly part
number changes.

Request To Revise the Compliance Cost

Sikorsky requested that we revise the estimated costs of complying
with the proposed AD. Specifically, Sikorsky advised that the number of
hours to replace a frame has increased from 3,360 to 5,000, while the
number of affected helicopters on the U.S. registry has decreased from
80 to 50.

We agree. We have revised the Costs of Compliance section
accordingly.

Request To Revise Summary

Sikorsky requested that we change the last sentence in SUMMARY,
which identifies the unsafe condition, to be consistent with the
language in the Unsafe Condition paragraph.

We agree that Sikorsky's proposal provides more consistency.
However, due to Administrative Committee of the Federal Register
publishing requirements, the specific unsafe condition is no longer
stated in SUMMARY. Thus, no change to this SNPRM is necessary.

Request To Update Contact Information

Sikorsky requested that we update the email address for its
Customer Service Engineering in both the preamble and the proposed AD.

We agree and have made the requested changes.

Request To Clarify the Related Service Information Section

Sikorsky requested that we revise the language in the Related
Service Information section describing the actions in ASB 92-53-012 and
SSI 92-074-E. Specifically, Sikorsky requests that we change
"replacing the fasteners" to "removing steel doublers, cold-working
holes, oversizing holes, trimming skin panels and reassembly with
interference fit fasteners." In support, Sikorsky stated the
recommended language would provide clarification.

We agree. We have made the requested changes accordingly.

Request To Clarify the Differences Section

Sikorsky requested that we clarify the Differences Between This
Proposed AD and the Service Information section. Specifically, Sikorsky
recommended adding "by this AD" to the sentence: "Contacting
Sikorsky would not be required."

We agree. We have revised the proposed AD accordingly.

Related Service Information

Sikorsky issued S-92 Alert Service Bulletin (ASB) 92-53-008, Basic
Issue, dated June 13, 2012 (ASB 92-53-008); S-92 ASB 92-53-009, Basic
Issue, dated December 6, 2012 (ASB 92-53-009); and ASB 92-53-012. ASB
92-53-008 provides procedures for a one-time inspection of the main
transmission frames and beams for a crack, missing or loose fastener or
collar, damage, deformation, and corrosion. ASB 92-53-009 specifies an
inspection before the first flight of the day and a recurring 150-hour
inspection of the interior and exterior surfaces of the upper flanges
and beams. ASB 92-53-012 specifies altering the forward and aft
transmission support frames by removing steel doublers, cold-working
the holes, oversizing the holes, trimming skin panels and reassembling
the parts with interference fit fasteners in accordance with SSI 92-
074-E. After this alteration, the parts are re-identified with a new
part number. Sikorsky refers to this alteration as a service life
extension program modification.

FAA's Determination

We are proposing this AD because we evaluated all the relevant
information and determined the unsafe condition described previously is
likely to exist or develop in other products of these same type
designs. Certain changes described above expand the scope of the NPRM.
As a result, we have determined that it is necessary to reopen the
comment period to provide additional opportunity for the public to
comment on this SNPRM.

Proposed Requirements of This SNPRM

This SNPRM would establish a life limit for certain part-numbered
frame assemblies by removing from service any part that has reached or
exceeded its new life limit. Frame assemblies that are altered under
Sikorsky's service life extension program and re-identified with a new
part number must be removed from service upon accumulating the life
limit of the old part-number or within certain hours TIS since the
alteration, whichever occurs first.

This SNPRM also would require, within 150 hours TIS and thereafter
at intervals not to exceed 150 hours TIS, inspecting STA 328 frame and
STA 362 frame for a crack or loose fasteners. If there is a crack or
loose fastener, this SNPRM would require repairing or replacing any
cracked part and any loose fastener before further flight.

Differences Between This SNPRM and the Service Information

The service information requires providing certain information to
Sikorsky, and this proposed AD would not. The service information
specifies performing a fluorescent penetrant inspection if there is a
suspected crack and contacting Sikorsky if there is a crack, while this
proposed AD would only require repairing or replacing any cracked part.
Contacting Sikorsky would not be required by this proposed AD.

Costs of Compliance

We estimate that this proposed AD would affect 50 helicopters of
U.S. Registry. We estimate that operators may incur the following costs
to comply with this proposed AD. Labor costs are estimated at $85 per
work-hour. We estimate a minimal cost to establish and revise the life
limit of the frame assembly. We estimate it would take 1 work-hour to
inspect STA 328 and 362 frames. No parts would be needed for a total
cost of $4,250 for the fleet for each inspection per inspection cycle.
If a fastener is replaced, we estimate the cost to be minimal. If a
frame is replaced, it would take 5,000 work-hours and required parts
would cost $296,000 for a total cost of $721,000 per helicopter.

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

We 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) Is not a "significant rule" under the 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.

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 (AD):