DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2012-0340; Directorate Identifier 2011-SW-073-AD]
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: We propose to adopt a new airworthiness directive (AD) for
certain Sikorsky Aircraft Corporation (Sikorsky) Model S-76C
helicopters. This proposed AD is prompted by a bird-strike to the
windshield that resulted in unintended movement of the engine control
levers from the forward position and towards the flight-idle position,
which reduced power on both engines. These actions are intended to
prevent unintended movement of the ECLs, resulting in main rotor speed
decay and subsequent loss of control of the aircraft.

DATES: We must receive comments on this proposed AD by May 29, 2012.

ADDRESSES: You may send comments by any of the following methods:

Federal eRulemaking Docket: Go to http://www.regulations.gov.
Follow the online instructions for sending your
comments electronically.

Fax: 202-493-2251.

Mail: Send comments to the U.S. Department of
Transportation, Docket Operations, M-30, West Building Ground Floor,
Room W12-140, 1200 New Jersey Avenue SE., Washington, DC 20590-0001.

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

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 proposed AD, the economic
evaluation, any comments received, and other information. The street
address for the Docket Operations Office (telephone 800-647-5527) is in
the ADDRESSES section. Comments will be available in the AD docket
shortly after receipt.

For service information identified in this proposed AD, contact
Sikorsky Aircraft Corporation, Attn: Manager, Commercial Technical
Support, mailstop s581a, 6900 Main Street, Stratford, CT, telephone
(203) 383-4866, email address tsslibrary@sikorsky.com, or at http://www.sikorsky.com.

You may review copies of the referenced service information at the
FAA, Office of the Regional Counsel, Southwest Region, 2601 Meacham
Blvd., Room 663, Fort Worth, Texas 76137.

FOR FURTHER INFORMATION CONTACT: Kirk Gustafson, Aerospace Engineer,
FAA, Boston Aircraft Certification Office, Engine and Propeller
Directorate, 12 New England Executive Park, Burlington, MA 01803;
telephone (781) 238-7190; email kirk.gustafson@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to participate in this rulemaking by submitting
written comments, data, or views. We also invite comments relating to
the economic, environmental, energy, or federalism impacts that might
result from adopting the proposals in this document. The most helpful
comments reference a specific portion of the proposal, explain the
reason for any recommended change, and include supporting data. To
ensure the docket does not contain duplicate comments, commenters
should send only one copy of written comments, or if comments are filed
electronically, commenters should submit only one time.

We will file in the docket all comments that we receive, as well as
a report summarizing each substantive public contact with FAA personnel
concerning this proposed rulemaking. Before acting on this proposal, we
will consider all comments we receive on or before the closing date for
comments. We will consider comments filed after the comment period has
closed if it is possible to do so without incurring expense or delay.
We may change this proposal in light of the comments we receive.

Discussion

We are proposing this AD as the result of an accident investigation
which concluded that a bird-strike to the upper portion of the
windshield caused significant forces to be transferred into the
overhead engine control quadrant assembly. This caused both ECLs to
move aft from the normal "FLY" position toward the "IDLE" position.
Unintended in-flight movement of the ECLs from the "FLY" position
significantly reduced engine power, and resulted in an unrecoverable
loss of main rotor speed and loss of control of the aircraft. A
subsequent National Transportation Safety Board (NTSB) investigation
resulted in a recommendation to modify the design of the engine control
quadrant to protect against unintended movement of the ECLs from
external force to the windshield or canopy. Sikorsky then issued Alert
Service Bulletin (ASB) No. 76-76-6A, Revision A, dated May 18, 2011
(ASB 76-76-6A) which describes procedures to modify the engine control
quadrant assembly with an improved throttle stop and a wider trigger
assembly.

FAA's Determination

We are proposing this AD because we evaluated all known relevant
information and determined that an unsafe condition exists and is
likely to exist or develop on other products of the same type design.

Related Service Information

We reviewed ASB 76-76-6A, which describes procedures for partially
disassembling the engine control quadrant assembly, removing the
existing throttle stop, and installing a new airworthy throttle stop.
The ASB also describes procedures to remove the existing trigger
assembly from each ECL and install a new airworthy wide trigger
assembly.

Proposed AD Requirements

This proposed AD would require, for S-76C model helicopters with
serial numbers 760506 and 760607 through 760812, within 6 months after
the effective date of the proposed AD, installing an improved throttle
stop and a wider trigger on each ECL as specified in the ASB.

Differences Between This Proposed AD and the Service Information

The Sikorsky ASB requires installation of the modifications on or
before March 7, 2012. The proposed AD requires installation within 6
months after the effective date of the AD.

Costs of Compliance

We estimate that this proposed AD would affect 52 helicopters of
U.S. Registry.

We estimate that operators may incur the following costs in order
to comply with this AD. To replace the engine control lever stop and
trigger assemblies will require 2 work-hours at an average labor cost
of $85 per hour. Required parts will cost about $939. Based upon these
costs, we estimate a total cost of $1,109 per helicopter and a total
cost of $57,668 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

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, 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 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 proposed 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.

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):