Airworthiness Directives; Sikorsky Aircraft Corporation (Sikorsky) Model S-92A Helicopters

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes adopting a new airworthiness directive (AD) for Sikorsky Model S-92A helicopters. This proposal would require revising the airworthiness limitations section of the Instructions for Continued Airworthiness (ICA) to reduce the life limit of the main gearbox housing and replacing any main gearbox housing that exceeds the life limit. This proposal is prompted by a fatigue analysis conducted after a helicopter was found with a severed main gearbox mounting foot pad (foot pad) that failed due to fatigue. The actions specified by this proposed AD are intended to prevent failure of the main gearbox mounting housing foot pad, loss of the main gearbox, and subsequent loss of control of the helicopter.

DATES:

Comments must be received on or before September 20, 2010.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD:

• 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.

You may examine the comments to this proposed AD in the AD docket on the Internet at http://www.regulations.gov.

FOR FURTHER INFORMATION CONTACT:

Michael Schwetz, Aviation Safety Engineer, Boston Aircraft Certification Office, 12 New England Executive Park, Burlington, MA 01803, telephone (781) 238-7761, fax (781) 238-7170.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any written data, views, or arguments regarding this proposed AD. Send your comments to the address listed under the caption ADDRESSES. Include the docket number “FAA-2010-0720, Directorate Identifier 2010-SW-050-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light 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 with FAA personnel concerning this proposed rulemaking. Using the search function of our docket web site, you can find and read the comments to any of our dockets, including the name of the individual who sent or signed the comment. You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78).

Examining the Docket

You may examine the docket that contains the proposed AD, any comments, and other information in person at the Docket Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Operations office (telephone (800) 647-5527) is located in Room W12-140 on the ground floor of the West Building at the street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

Discussion

This document proposes adopting a new AD for Sikorsky Model S-92A helicopters. This proposal would require revising the airworthiness limitations section of the ICA to reduce the life limit of the main gearbox housing from 2700 hours time-in-service (TIS) to 1000 hours TIS and to replace any main gearbox housing that exceeds the lower life limit. This proposal is prompted by review of a fatigue analysis conducted after a helicopter was found with a severed foot pad due to the effect of fatigue of the main gearbox housing. This condition, if not corrected, could result in failure of the main gearbox housing mounting foot pad, loss of the main gearbox, and subsequent loss of control of the helicopter.

This unsafe condition is likely to exist or develop on other helicopters of the same type design. Therefore, the proposed AD would require, within 60 days, revising the airworthiness limitations section of the ICA to reduce the life limit of the main gearbox housing from 2700 hours TIS to 1000 hours TIS and replacing, before further flight, any main gearbox housing that has exceeded the 1000-hour TIS life limit.

We estimate that this proposed AD would affect 15 helicopters of U.S. registry, and the proposed actions would take about 112 work hours per helicopter at an average labor rate of $85 per work hour. Required parts would cost about $200,000 per helicopter. Based on these figures, we estimate the total cost impact of the proposed AD on U.S. operators would be $3,142,800, assuming all 15 helicopters replace the main gearbox housing.

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. Additionally, 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 that the 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); and

3. 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 a draft economic evaluation of the estimated costs to comply with this proposed AD. See the AD docket to examine the draft economic evaluation.

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.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (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.