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Proposed Rule

Airworthiness Directives; Sikorsky Aircraft Corporation Helicopters

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Federal Aviation Administration (FAA), DOT.


Notice of proposed rulemaking (NPRM).


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.


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


You may send comments by any of the following methods:

  • Federal eRulemaking Docket: Go to 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 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, or at

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.

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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

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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.


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.Start Printed Page 18970

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.

Start List of Subjects

List of Subjects in 14 CFR Part 39

  • Air transportation
  • Aircraft
  • Aviation safety
  • Incorporation by reference
  • Safety
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The Proposed Amendment

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

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

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

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2. The FAA amends § 39.13 by adding the following new Airworthiness Directive (AD):

Sikorsky Aircraft Corporation: Docket No. FAA-2012-0340; Directorate Identifier 2011-SW-073-AD.

(a) Applicability

This AD applies to Sikorsky Aircraft Corporation (Sikorsky) Model S-76C helicopters, serial numbers 760506 and 760607 through 760812, certificated in any category.

(b) Unsafe Condition

This AD defines the unsafe condition as unintended movement of the engine control levers due to an external force to the windshield or canopy. This condition could result in significantly reduced engine power, unrecoverable loss of main rotor speed, and subsequent loss of control of the helicopter.

(c) Compliance

You are responsible for performing each action required by this AD within the specified compliance time unless accomplished previously.

(d) Required Action

Within 6 months, replace the throttle stop and trigger assembly on each engine control lever and perform a throttle position check as specified in the Accomplishment Instructions, Sections 3.A and 3.B, of Sikorsky Alert Service Bulletin No. 76-76-6A Revision A, dated May 18, 2011.

(e) Alternative Methods of Compliance (AMOC)

(1) The Manager, Boston Aircraft Certification Office, FAA, may approve AMOCs for this AD. Send your proposal to: 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

(2) For operations conducted under a Part 119 operating certificate or under Part 91, Subpart K, we suggest that you notify your principal inspector, or lacking a principal inspector, the manager of the local flight standards district office or certificate holding district office before operating any aircraft complying with this AD through an AMOC.

(f) Subject

Joint Aircraft Service Component (JASC) Code: 7600: Engine Controls.

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Issued in Fort Worth, Texas, on March 20, 2012.

Kim Smith,

Manager, Rotorcraft Directorate, Aircraft Certification Service.

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[FR Doc. 2012-7541 Filed 3-28-12; 8:45 am]