AD 2004-26-02

This AD becomes effective January 26, 2005.

You may examine the AD docket at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA.

Robert Grant, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-7757; fax (781) 238-7199.

The FAA proposed to amend 14 CFR part 39 with a proposed AD. The proposed AD applies to GE CF34-3A, CF34-3A2, CF34-1A, CF34-3A1, CF34-3B, and CF34-3B1 series turbofan engines. We published the proposed AD in the Federal Register on May 18, 2004 (69 FR 28093). That action proposed to require removal from service of certain HPC forward spools, at the first piece-part level exposure after 6,000 CSN, but not later than 20,000 CSN for CF34-3B engines and not later than 22,000 CSN for CF34-3A, CF34-3A2, CF34-1A, CF34-3A1, and CF34-3B1 engines. That action results from GE updating the LCF analysis for these HPC forward spools.

You may examine the AD Docket (including any comments and service information), by appointment, between 8 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays. See ADDRESSES for the location.

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

One commenter requests that we clarify the definition of a serviceable HPC forward spool. The commenter states that a clarification would ensure that operators are not led to believe that HPC forward spools installed in their engines are not serviceable based on the AD's definition of a serviceable HPC forward spool.

We partially agree. As written in the proposal, the compliance requires replacing certain HPC forward spools with a serviceable HPC forward spool at next piece-part level exposure, and then defines what a serviceable HPC forward spool is and what it is not. We agree that this definition could cause confusion. We do not agree that a clarification to the existing definition is the best approach to ensure that the AD is understandable. For clarification, we have rewritten the compliance in the final rule to require operators to remove certain specific spools from service. We have also added a paragraph in the final rule to clarify that after the effective date of this AD, do not install any HPC forward spool, P/N 6078T56P03. We have also clarified the requirement that after the effective date of this AD, do not install any HPC forward spool, P/N 6078T56P04, with more than 0 CSN. We have also deleted from the final rule the definition which described serviceable spools.

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.

There are about 2,681 GE CF34-3A, CF34-3A2, CF34-1A, CF34-3B and CF34-3B1 series turbofan engines of the affected design in the worldwide fleet. We estimate that 1,826 engines installed on airplanes of U.S. registry would be affected by this AD. We also estimate that 59% of the replacements will not be done at piece-part exposure, and will require approximately 650 work hours per engine to perform the actions, and that the average labor rate is $65 per work hour. Required parts will cost about $16,000 per engine (a prorated cost of the unused spool life to the original life). Based on these figures, we estimate the total cost of the AD to U.S. operators to be $74,420,000.

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 by sending a request to us at the address listed under ADDRESSES. Include “AD Docket No. 2003-NE-67-AD” in your request.

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 (AD):