2010-11423. Airworthiness Directives; Sikorsky Aircraft Corporation (Sikorsky) Model S-70A and S-70C Helicopters

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes adopting a new airworthiness directive (AD) for the Sikorsky Model S-70A and S-70C helicopters. This proposal would require an ultrasonic test (UT) inspection of the tail gearbox output bevel gear (gear) for a crack. If you find a crack, replacing the gear with an airworthy gear before further flight would be required. This proposal is prompted by three gear cracking incidents, one of which resulted in the tail rotor separating from the helicopter. The actions specified by this proposed AD are intended to detect a crack in the gear to prevent a tail rotor separating, loss of tail rotor control, and subsequent loss of control of the helicopter.

DATES:

Comments must be received on or before July 12, 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: [phone].
• 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 get the service information identified in this proposed AD from Sikorsky Aircraft Corporation, Attn: Manager, Commercial Technical Support, mailstop s581a, 6900 Main Street, Stratford, CT, telephone [phone], e-mail address [e-mail], or at http://www.sikorsky.com.

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:

Terry Fahr, Aviation Safety Engineer, Boston Aircraft Certification Office, 12 New England Executive Park, Burlington, MA 01803, telephone [phone], fax [phone].

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-2010-0490, Directorate Identifier 2010-SW-037-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 [phone]) 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 the Sikorsky Model S-70A and S-70C helicopters. This proposal would require a UT inspection of the gear for a crack. If you find a crack, replacing the gear with an airworthy gear would be required before further flight. This proposal is prompted by three gear crack incidents, one of which resulted in the tail rotor separating from the helicopter. The tail gearbox on the helicopter where the tail rotor separated from the helicopter experienced a fracture of the output shaft spline that drives the tail rotor blades. An investigation into the cause of the cracks is ongoing. The unsafe condition described previously, if not corrected, could result in a tail rotor separating, loss of tail rotor control, and subsequent loss of control of the helicopter.

We have reviewed Sikorsky Alert Service Bulletin No. 70-06-28A, Revision A, dated May 21, 2009 (ASB), which refers to procedures for a UT inspection of the gear in accordance with Special Service Instructions (SSI) No. 70-121A or latest revision.

This unsafe condition is likely to exist or develop on other helicopters of the same type design. Therefore, the proposed AD would require a UT inspection of the gear, part number 70358-06620, for a crack. If you find a crack, the AD requires replacing the gear with an airworthy gear before further flight. The actions would be required to be to be done by following the SSI described previously.

We estimate that this proposed AD would affect 5 helicopters of U.S. registry, and the proposed actions would take about 4 work hours per helicopter at an average labor rate of $85 per work hour. Required parts would cost about $20,000 for each gear. Based on these figures, we estimate the total cost impact of the proposed AD on U.S. operators to be $101,700, assuming the gear is replaced on the entire fleet.

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
• Incorporation by reference
• 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.

§ 39.13

[Amended]

2. Section 39.13 is amended by adding a new airworthiness directive to read as follows:

Sikorsky Aircraft Corp.: Docket No. FAA-2010-0490; Directorate Identifier 2010-SW-037-AD.

Applicability

Model S-70A and S-70C helicopters, tail gearbox output bevel gear (gear), part number 70358-06620, certificated in any category.

Compliance

Required as indicated.

To prevent a tail rotor separating, loss of tail rotor control, and subsequent loss of control of the helicopter, do the following:

(a) Within 500 hours time-in-service (TIS), unless accomplished previously, and thereafter at intervals not to exceed 500 hours TIS, remove the tail rotor servo control and pitch beam shaft, and using a Level II Ultrasonic Testing Technician or equivalent, ultransonic inspect the gear for a crack. Ultrasonic inspect the gear by following paragraphs A.(5)a. through A(5)n., Note 7, Special Service Instructions (SSI) No. 70-121A, Revision A, dated May 21, 2009. If you find a crack, before further flight, replace the gear with an airworthy gear.

(b) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Contact the Manager, Boston Aircraft Certification Office, FAA, ATTN: Terry Fahr, Aviation Safety Engineer, Boston Aircraft Certification Office, 12 New England Executive Park, Burlington, MA 01803, telephone [phone], fax [phone], for information about previously approved alternative methods of compliance.

(c) The Joint Aircraft System/Component (JASC) Code is: 6520: Tail rotor gearbox.

Issued in Fort Worth, Texas, on May 3, 2010.

Mark R. Schilling,

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.