AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

SUMMARY: We are adopting a new airworthiness directive (AD) for
Sikorsky Model S-70, S-70A, S-70C, S-70C (M), and S-70C (M1)
helicopters with General Electric (GE) T700-GE-401C or T700-GE-701C
engines installed. This AD requires establishing new fatigue life
limits for certain GE engine gas generator turbine (GGT) rotor parts.
This AD was prompted by a reevaluation of the method for determining
the life limit for certain GE engine GGT rotor parts and the
determination that these life limits should be based on low cycle
fatigue (LCF) events instead of hours time-in-service (TIS). The
actions are intended to prevent fatigue failure of a GGT rotor part,
engine failure, and subsequent loss of control of the helicopter.

DATES: This AD is effective February 10, 2014.
The Director of the Federal Register approved the incorporation by
reference of certain documents listed in this AD as of February 10,
2014.

ADDRESSES: For service information identified in this AD, contact
Sikorsky Aircraft Corporation, Attn: Manager, Commercial Technical
Support, mailstop s581a, 6900 Main Street, Stratford, CT, telephone
(800) 562-4409, email address tsslibrary@sikorsky.com, or at http://
www.sikorsky.com. You may review a copy of the referenced service
information at the FAA, Office of the Regional Counsel, Southwest
Region, 2601 Meacham Blvd., Room 663, Fort Worth Texas 76137.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.
gov or in person at the Docket Operations Office
between 9 a.m. and 5 p.m., Monday through Friday, except Federal
holidays. The AD docket contains this AD, any incorporated-by-reference
service information, the economic evaluation, any comments received,
and other information. The street address for the Docket Operations
Office (phone: 800-647-5527) is U.S. Department of Transportation,
Docket Operations Office, M-30, West Building Ground Floor, Room W12-
140, 1200 New Jersey Avenue SE., Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Michael Davison, Flight Test Engineer,
New England Regional Office, FAA, 12 New England Executive Park,
Burlington, MA 01803; phone: (781) 238-7156; fax: (781) 238-7170;
email: michael.davison@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

On September 7, 2012, at 77 FR 55166, the Federal Register
published our notice of proposed rulemaking (NPRM), which proposed to
amend 14 CFR part 39 by adding an AD that would apply to Sikorsky Model
S-70, S-70A, S-70C, S-70C (M), and S-70C (M1) helicopters with GE T700-
GE-401C or T700-GE-701C engines installed. The NPRM proposed
establishing new fatigue life limits for certain GE engine GGT rotor
parts, based upon a formula in GE's service information. The NPRM was
prompted by the determination that the affected engines could fail due
to fatigue unless the life limits of certain GE engine rotor parts are
changed from hours TIS to LCF events.
On July 23, 2013, at 78 FR 44052, the Federal Register published
our supplemental notice of proposed rulemaking (SNPRM), which proposed
to revise the formula in the NPRM for establishing the new fatigue life
limits by using the correct formula in a newer revision of GE's service
information. Also, the SNPRM corrected a typographical error made in
the preamble of the previous NPRM in the ``Related Service
Information,'' which referenced the service bulletin number as 72-041
rather than the correct service bulletin number 72-0041.
The proposed actions in the SNPRM were intended to prevent failure
of a GGT rotor part, engine failure, and subsequent loss of control of
the helicopter.

Comments

We gave the public the opportunity to comment on the NPRM (77 FR
55166, September 7, 2012), and the SNPRM (78 FR 44052, July 23, 2013),
but we did not receive any comments.

FAA's Determination

We have reviewed the relevant information and determined that an
unsafe condition exists and is likely to exist or develop on other
products of these same type designs and that air safety and the public
interest require adopting the AD requirements as proposed in the SNPRM
(78 FR 44052, July 23, 2013).

Costs of Compliance

We estimate that this AD will affect 9 helicopters of U.S.
registry. We estimate that operators may incur the following costs in
order to comply with this AD: A minimal amount for work hours and labor
costs because these parts are replaced as part of the periodic
maintenance on the helicopter; a minimal amount of time to calculate
the new retirement life; $360,000 to replace the GGT rotor parts per
helicopter; and $3,240,000 to replace the GGT rotor parts for the
entire U.S. operator fleet.

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 to the extent
that it justifies making a regulatory distinction; 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.
We prepared an economic evaluation of the estimated costs to comply
with this AD and placed it in the AD docket.

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

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):