2010-1521. 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 the Sikorsky Model S-92A helicopters. The AD would require replacing the main gearbox (MGB) filter bowl assembly with a two-piece MGB filter bowl assembly and replacing the existing mounting studs. The AD would also require inspecting the MGB lube system filters, the housing, the housing threads, and the lockring counterbore and repairing or replacing them as necessary. This proposed AD is prompted by tests indicating that an existing MGB filter bowl assembly can fail under certain loading conditions including those associated with a damaged MGB filter or mounting stud resulting from high frequency maintenance tasks. Testing of the improved MGB filter bowl assembly demonstrates a significant increase in strength and durability over the existing filter bowl. The actions specified by this proposed AD are intended to prevent failure of the MGB filter bowl assembly due to failure of the mounting studs or the filter bowl, loss of oil from the MGB, failure of the MGB, and subsequent loss of control of the helicopter.

DATES:

Comments must be received on or before March 29, 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.

FOR FURTHER INFORMATION CONTACT:

Kirk Gustafson, Aviation Safety Engineer, Boston Aircraft Certification Office, Engine and Propeller Directorate, FAA, 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-2010-0060, Directorate Identifier 2010-SW-06-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.

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-92A helicopters. The AD would require replacing the MGB filter bowl assembly with a two-piece MGB filter bowl assembly and replacing the existing mounting studs. The AD would also require inspecting the MGB lube system filters, the housing, the housing threads, and the lockring counterbore and repairing and replacing them as necessary. This proposed AD is prompted by tests indicating the existing MGB filter bowl assembly can fail under certain loading conditions including those associated with a damaged MGB filter or mounting stud resulting from high frequency maintenance tasks that can lead to complete loss of oil from the MGB. Testing of the improved MGB filter bowl assembly demonstrates a reduced susceptibility to damage of MGB filter bowl assembly during routine maintenance. This proposed AD is intended to prevent failure of the MGB filter bowl assembly due to failure of the mounting studs or the filter bowl, loss of oil from the MGB, failure of the MGB, and subsequent loss of control of the helicopter.

We have reviewed Sikorsky Alert Service Bulletin No. 92-63-022A, dated December 18, 2009 (ASB), which describes procedures for replacing the existing MGB filter bowl assembly with a new, two-piece filter bowl assembly. The ASB also describes procedures for replacing the existing studs with new studs.

This unsafe condition is likely to exist or develop on other helicopters of the same type design. Therefore, the proposed AD would require the following within 60 days.

• Removing the MGB filter bowl assembly and the MGB lube system filter.
• Removing the primary filter element, part number (P/N) 70351-38801-102, and visually inspecting it for damage. If the primary filter element has “wavy” pleats, internal buckling, or indented dimples, before further flight, replacing it with an airworthy filter element.
• Visually inspecting the secondary filter element, P/N 70351-38801-103, for damage. If the secondary filter element has “wavy” pleats or an elongated cup, before further flight, replacing it with an airworthy filter element.
• Replacing the MGB lube system filter assembly mounting studs by removing the studs and visually inspecting the tapped holes for any damage to the threads, visually inspecting the housing to determine that the housing threads are free from damage and corrosion, and visually inspecting housing lockring counterbore to determine if the housing is airworthy.
• If you find damage or corrosion to the housing threads, the housing, or the lockring counterbore, stopping work and contacting the FAA.
• If you do not find damage to the housing threads, the housing, or the lockring counterbore that requires repair, replacing the mounting studs.
• Installing an airworthy, two-piece MGB filter bowl assembly modification kit, P/N 92070-35005-011.

The AD would require that specified portions of the ASB be followed.

We estimate that this proposed AD would affect 22 helicopters of U.S. registry. We also estimate that it would take about 6 hours to inspect the existing filter bowl assembly and replace the MGB lube system filters, the mounting studs, and to install an improved filter bowl assembly at an average labor rate of $80 per work hour. Required parts would cost about $3,257 per helicopter. Based on these figures, the total cost impact of the proposed AD on U.S. operators would be $82,214.

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 Corporation: Docket No. FAA-2010-0060; Directorate Identifier 2010-SW-06-AD.

Applicability: Model S-92A helicopters, with main gearbox (MGB) filter bowl assembly, part number (P/N) 92351-15802-101, installed, certificated in any category.

Compliance: Required as indicated, unless done previously.

To prevent failure of the MGB filter bowl assembly due to failure of the mounting studs or the filter bowl, loss of oil from the MGB, failure of the MGB, and subsequent loss of control of the helicopter, do the following:

(a) Within 60 days:

(1) Remove the MGB filter bowl assembly by following the Accomplishment Instructions, paragraphs 3.A.(1) through 3.A.(5), of Sikorsky Alert Service Bulletin No. 92-63-022A, dated December 18, 2009 (ASB).

(2) Remove the primary filter element, P/N 70351-38801-102, from the MGB lube system filter and visually inspect it for damage as depicted in Figures 1, 2, and 3 of the ASB. If the primary filter element has “wavy” pleats, internal buckling, or indented dimples, before further flight, replace it with an airworthy filter element.

(3) Visually inspect the secondary filter element, P/N 70351-38801-103, for damage as depicted in Figures 4 and 5 of the ASB. If the secondary filter element has “wavy” pleats or an elongated cup, before further flight, replace it with an airworthy filter element.

(4) Replace the MGB lube system filter assembly mounting studs:

(i) Remove the studs by following the Accomplishment Instructions, paragraphs 3.B.(1) through 3.B.(4) of the ASB. Visually inspect the tapped holes for any damage to the threads. Serrations on the entire counter bore (360 degrees) are acceptable. Serrations in the housing must be intact, and mating serrations on the lock ring must line up with serrations on the housing. Visually inspect the housing to determine that the housing threads are free from damage and corrosion. Visually inspect housing lockring counterbore to determine if the housing is airworthy.

(ii) If you find damage or corrosion to the housing threads, the housing, or the lockring counterbore, stop work and contact Kirk Gustafson, Aviation Safety Engineer, Boston Aircraft Certification Office, Engine and Propeller Directorate, FAA, 12 New England Executive Park, Burlington, MA 01803, telephone [phone], fax [phone].

(iii) If you do not find damage to the housing threads, the housing, or the lockring counterbore that requires repair, replace the mounting studs by following the Accomplishment Instructions, paragraphs 3.B.(7) through 3.B.(15) of the ASB.

(5) Install an airworthy, two-piece MGB filter bowl assembly modification kit, P/N 92070-35005-011, as depicted in Figures 8 and 9 of the ASB and by following the Accomplishment Instructions, paragraphs 3.C.(1) through 3.C.(20), of the ASB.

(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, ATTN: Kirk Gustafson, Aviation Safety Engineer, Boston Aircraft Certification Office, Engine and Propeller Directorate, FAA, 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 6320: Main Rotor Gearbox.

Issued in Fort Worth, Texas, on January 20, 2010.

Mark R. Schilling,

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.