AD 2009-08-06

This AD becomes effective May 18, 2009.

The Docket Operations office is located at Docket Management Facility, U.S. Department of Transportation, 1200 New Jersey Avenue, SE., West Building Ground Floor, Room W12-140, Washington, DC 20590-0001.

Robert Green, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: robert.green@faa.gov; telephone: (781) 238-7754, fax: (781) 238-7199.

The FAA proposed to amend 14 CFR part 39 with a proposed AD. The proposed AD applies to GE CF6-80A series turbofan engines with certain stage 1 HPT rotor disks, installed. We published the proposed AD in the Federal Register on September 4, 2008 (73 FR 51604). That action proposed to require removal from service of those stage 1 HPT rotor disks within 30 days after the effective date of the AD.

You may examine the AD docket on the Internet at http://www.regulations.gov; or in person at the Docket Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Operations office (telephone (800) 647-5527) is provided in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

We provided the public the opportunity to participate in the development of this AD. We have considered the comment received.

One commenter, FedEx Express, claims that we greatly underestimated the actual cost of compliance with the proposed AD. The proposed AD estimated 1 work-hour of labor. The commenter states that this estimate is accurate only when the engine is already removed and disassembled to piece-part exposure of the disk. The commenter states that the true cost to an airline, both in disruption to the operation and in the subsequent unplanned engine shop visit, would vastly exceed 1 work-hour.

We agree that the cost of compliance should also cover the work-hours for an unplanned engine shop visit. We do not agree that it should factor in the cost of disruption to the operation. We are required to calculate only the direct cost to an operator, of labor and parts. We changed the cost of compliance paragraph to include an estimate for an unplanned engine shop visit.

Since we issued the proposed AD, we clarified the unsafe condition statement as to where potential cracks could occur in the disk. We changed “cracks developing in the bottoms of the dovetail slots” to “cracks developing at the aft chamfer of the blade dovetail slots.”

We have carefully reviewed the available data, including the comment received, and determined that air safety and the public interest require adopting the AD with the changes described previously. We have determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

We estimate that this AD will affect 3 out of 316 CF6-80A series turbofan engines installed on airplanes of U.S. registry. We also estimate that it will take about 1 work-hour per engine to perform the actions if the engine is already removed and disassembled to piece-part exposure of the disk, and will take about 115 work-hours per engine for an unplanned engine shop visit. The average labor rate is $80 per work-hour. Required parts would cost about $300,000 per engine. Based on these figures, we estimate the total cost of the AD to U.S. operators to be $927,600.

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.

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 this AD:

(1) Is not a “significant regulatory action” under Executive Order 12866;

(2) Is not a “significant rule” under 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 summary of the costs to comply with this AD and placed it in the AD Docket. You may get a copy of this summary at the address listed under ADDRESSES.

Accordingly, under the authority delegated to me by the Administrator, the Federal Aviation Administration amends 14 CFR part 39 as follows:

1. The authority citation for part 39 continues to read as follows:

2. The FAA amends § 39.13 by adding the following new airworthiness directive: