AD 2010-18-13

This AD becomes effective October 18, 2010. The Director of the Federal Register approved the incorporation by reference of certain publications listed in the regulations as of October 18, 2010.

You can get the service information identified in this AD from Pratt & Whitney, 400 Main St., East Hartford, CT 06108; telephone (860) 565-7700; fax (860) 565-1605.

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.

Rose Len, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: rose.len@faa.gov; telephone (781) 238-7772; fax (781) 238-7199.

The FAA proposed to amend 14 CFR part 39 with a proposed AD. The proposed AD applies to PW PW4000 series turbofan engines. We published the proposed AD in the Federal Register on March 25, 2010 (75 FR 14375). That action proposed to require initial and repetitive FPI for cracks in the blade locking and loading slots of the HPC drum rotor disk assembly.

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 comments received.

Two commenters, United Services and Boeing, concurred with the AD as proposed.

One commenter, a private citizen, requested that we reference the latest SB in the AD, which is Pratt & Whitney SB No. PW4G-112-72-264, Revision 2, dated February 23, 2010.

We agree. We changed the AD to use the most current version of the SB.

One commenter, Delta Tech Ops, requested that we change the inspection compliance time to be done only when all of the blades of a specific stage are removed, rather than when any of the blades from a specific stage are removed, as written in the proposed AD. The commenter states that doing the inspection when any blades are removed is an added maintenance burden.

We do not agree. Our risk assessment establishes that, because the rotating life-limited parts addressed by this AD action have a known cracking problem, the parts must be inspected at the times stated in the AD. Inspection can be done without removing all of the blades, by sliding remaining installed blades to expose the locking and loading slots for local fluorescent penetrant inspection. We did not change the AD.

Since we issued the proposed AD, we became aware that we inadvertently listed engine model PW4156. We removed that engine model from the AD.

We have carefully reviewed the available data, including the comments 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 1,038 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, and that the average labor rate is $85 per work-hour. No parts are required. Based on these figures, we estimate the total cost of the AD to U.S. operators to be $88,230.

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: