AD 2009-23-51

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 2009-23-51, which was sent previously to all known U.S. owners and operators of Sikorsky Aircraft Corporation (Sikorsky) Model S-92A helicopters by individual letters. This AD requires cleaning and inspecting each main gearbox (MGB) assembly mounting foot pad and rib for a crack and corrosion. If you do not find a crack, the AD requires applying a corrosion preventive compound. If you find a crack, the AD requires replacing the MGB before further flight. If you find corrosion, bubbled paint, or paint discoloration, the AD also requires you to repair the MGB before further flight. This amendment is prompted by reports of cracks in the MGB mounting foot pads and foot ribs. This condition, if not detected, could result in loss of the MGB and subsequent loss of control of the helicopter.

Final rule; request for comments.

2009-23-51 Sikorsky Aircraft Corporation: Amendment 39-16190. Docket No. FAA-2010-0066; Directorate Identifier 2009-SW-52-AD.

Applicability: Model S-92A helicopters, with main gearbox (MGB) assembly, part number (P/N) 92351-15000-042 or -043, with MGB housing, P/N 92351-15110-042, -043, -044, or -045, installed, certificated in any category.

Compliance: Required as indicated.

To prevent loss of an MGB and subsequent loss of control of the helicopter, do the following:

(a) Within 10 hours time-in-service (TIS), unless accomplished previously, and thereafter at intervals not to exceed 10 hours TIS, clean and inspect each MGB assembly mounting foot pad and rib for a crack and corrosion in the area depicted in Figure 1; as shown in the examples in Figures 2, 3, and 4; of Sikorsky Alert Service Bulletin No. 92-63-020, dated September 11, 2009 (ASB). If no crack is found, apply the corrosion preventive compound to each foot pad and rib area.

Note 1: When conductinga visual inspection, use a bright, non- LED light.

(1) If you find a crack, replace the MGB before further flight.

(2) If you find corrosion, bubbled paint, or paint discoloration, before further flight, repair the affected area.

Note 2: Following the ASB Accomplishment Instructions accomplishes the intent of this AD.

(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: Michael Schwetz, Aviation Safety Engineer, 12 New England Executive Park, Burlington, MA 01803, telephone (781) 238-7761, fax (781) 238- 7170, for information about previously approved alternative methods of compliance.

(c) The Joint Aircraft System/Component (JASC) Code is 6320: Main Rotor Gearbox.

(d) Do the inspections by following the specified portions of Sikorsky Alert Service Bulletin No. 92-63-020, dated September 11, 2009. The Director of the Federal Register approved this incorporation by reference under 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Sikorsky Aircraft Corporation, Attn: Manager, Commercial Technical Support, mailstop s581a, 6900 Main Street, Stratford, CT, telephone (203) 383-4866, e-mail address tsslibrary@sikorsky.com, or at http://www.sikorsky.com. Copies may be inspected at the FAA, Office of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas, or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_ regulations/ibr_locations.html.

(e) This amendment becomes effective on February 19, 2010, to all persons except those persons to whom it was made immediately effective by Emergency AD 2009-23-51, issued October 29, 2009, which contained the requirements of this amendment.

On October 29, 2009, the FAA issued Emergency AD 2009-23-51 for the Sikorsky Model S-92A helicopters, which requires cleaning and inspecting each MGB assembly mounting foot pad and rib for a crack and corrosion. If you do not find a crack, the AD requires applying a corrosion preventive compound. If you find a crack, the AD requires replacing the MGB before further flight. If you find corrosion, bubbled paint, or paint discoloration, the AD also requires you to repair the MGB before further flight. This amendment is prompted by reports of cracks in the MGB mounting foot pads and foot ribs. The manufacturer is investigating the root cause of these cracks. Contributing factors may include corrosion and the bushing press fit in the mounting foot bolt hole. This condition, if not detected, could result in loss of the MGB and subsequent loss of control of the helicopter.

We have reviewed Sikorsky Alert Service Bulletin No. 92-63-020, dated September 11, 2009(ASB), which describes procedures for visually inspecting the MGB assembly mounting foot pads and foot ribs for a crack and corrosion. The ASB specifies a 10-hour recurring visual inspection. If you suspect a crack, the ASB specifies a fluorescent penetrant inspection (FPI) or a dye penetrant inspection (DPI). If you find a crack, the ASB specifies replacing the MGB before further flight. Also, the ASB specifies treating any corrosion.

This unsafe condition is likely to exist or develop on other helicopters of the same type design. Therefore, this AD requires within 10 hours time-in-service (TIS), unless accomplished previously, and thereafter at intervals not to exceed 10 hours TIS, cleaning and inspecting each MGB assembly mounting foot pad and rib for a crack and corrosion. If you do not find a crack, the AD requires applying a corrosion preventive compound. If you find a crack, the AD requires replacing the MGB before further flight. If you find corrosion, bubbled paint, or paint discoloration, this AD also requires you to repair the MGB before further flight. The actions specified in this AD are interim actions until the root cause of the cracking is determined. After that determination, we anticipate further rulemaking.

Since it was found that immediate corrective action was required, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual letters issued on October 29, 2009, to all known U.S. owners and operators of Sikorsky Model S-92A helicopters. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to 14 CFR 39.13 to make it effective to all persons.

The FAA estimates that this AD will affect 44 helicopters of U.S. registry, and inspecting the MGB assembly mounting foot pads and foot ribs for corrosion or a crack will take about:

2 work hours to do the visual inspection, assuming 2,200 (50 x 44 helicopters) inspections per year for commercial and part 91 operators; and

24 work hours to remove and replace an MGB.

The average labor rate is $80 per work hour and required parts will cost about $590,000 per helicopter. Based on these figures, we estimate the total cost impact of the AD on U.S. operators to be $5,087,360, assuming 8 helicopters will require an MGB replacement.

Comments Invited

This AD is a final rule that involves requirements that affect flight safety and was not preceded by notice and an opportunity for public comment; however, we invite you to submit any written data, views, or arguments regarding this AD. Send your comments to an address listed under ADDRESSES. Include "Docket No. FAA-2010-0066; Directorate Identifier 2009-SW-52-AD'' at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the AD. We will consider all comments received by the closing date and may amend the 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 AD. 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 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).

Regulatory Findings

We have determined that this AD will not have federalism implications under Executive Order 13132. This AD will 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 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 an economic evaluation of the estimated costs to comply with this AD. See the AD docket to examine the 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.

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends 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.

Sec. 39.13 [Amended]

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