This amendment adopts a new AD for the Sikorsky Model S-92A helicopters. This action requires, before further flight, replacing tail gear box output housing, part number (P/N) 92358-06109-043, that has 600 or more hours TIS with an airworthy gear box output housing with less than 600 hours TIS. Also, this AD revises the Airworthiness Limitations section of the maintenance manual by reducing the life limit of the tail gear box output housing from 4500 hours TIS to 600 hours TIS. This amendment is prompted by the premature failure of the tail gear box output housing during fatigue testing by the manufacturer. The follow-on investigation indicated the manufacturing process created an oxide skin defect in the housing, making it necessary to reduce the life limit of the gear box housing from 4500 hours TIS to 600 hours TIS. The manufacturer is reviewing its processes on the output housing to determine methods, including a material change, to prevent the oxide skindefect.
In Chapter 4 of the Sikorsky S-92 Maintenance Manual, SA S92A-AWL- 000, the tail gear box output housing is noted as a critical part. Further, in Note 12 to those Airworthiness Limitations and Inspection Requirements, the manufacturer states to remove the Tail Gear Box Assembly, P/N 92358-06100-043, which contains the Tail Gear Box Output Housing, P/N 92358-06109-043, and send it "to a manufacturer authorized repair center for replacement of the time limited components." This AD does not require you to send the gear box assembly or output housing to a manufacturer authorized repair center or to the manufacturer. However, any entity removing and replacing the gear box assembly, output housing, or the critical parts within each of those components must be qualified and have approved data to perform that maintenance.
This unsafe condition is likely to exist or develop on other helicopters of the same type design. Therefore, this AD is being issued to prevent fatigue failure of the tail gear box output housing, loss of tail rotor drive, and subsequent loss of control of the helicopter. This AD requires, before further flight, replacing each tail gear box output housing, P/N 92358-06109-043, with 600 or more hours TIS with an airworthy part. Also, this AD revises the Airworthiness Limitations section of the maintenance manual by reducing the life limit of the tail gear box output housing from 4500 hours TIS to 600 hours TIS.
The short compliance time involved is required because the previously described critical unsafe condition can adversely affect the controllability or structural integrity of the helicopter. Some operators may have already exceeded the 600 hours TIS. Therefore, replacing each tail gear box output housing that has reached 600 or more hours TIS with an airworthy tail gear box output housing is required before further flight and this AD must be issued immediately.
Since a situation exists that requires the immediate adoptionof this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.
We estimate that this AD will affect 4 helicopters of U.S. registry, and replacing the tail gear box output housing will take about 8 work hours at an average labor rate of $65 per work hour. Required parts will cost about $4291 per helicopter. Based on these figures, we estimate the total cost impact of the AD on U.S. operators to be $19,244.
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-2005-21588; Directorate Identifier 2005-SW-24-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://dms.dot.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), or you may visit http://dms.dot.gov .
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 DMS 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, 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: