Airworthiness Directives; General Electric Company CF6-80C2 and CF6-80E1 Series Turbofan Engines

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for General Electric Company (GE) CF6-80C2 and CF6-80E1 series turbofan engines with high-pressure compressor rotor (HPCR) spool shaft stage 14 disks, part number (P/N) 1703M49G02, 1703M49G03, or 1509M71G10 installed. This proposed AD would require a one-time eddy current inspection (ECI) of the HPCR spool shaft stage 14 disk web for crack indications, and removing from service any parts with web cracks. This proposed AD results from reports of 12 HPCR spool shaft stage 14 disks with web cracks discovered to date. We are proposing this AD to prevent cracks from propagating to an uncontained failure of the disk and damage to the airplane.

DATES:

We must receive any comments on this proposed AD by January 26, 2009.

ADDRESSES:

Use one of the following addresses to comment on this proposed AD.

• Federal eRulemaking Portal: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility, U.S. Department of Transportation, 1200 New Jersey Avenue, SE., West Building Ground Floor, Room W12-140, Washington, DC 20590-0001.
• Hand Delivery: Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.
• Fax: (202) 493-2251.

You can get the service information identified in this proposed AD from General Electric Company via Lockheed Martin Technology Services, 10525 Chester Road, Suite C, Cincinnati, Ohio 45215, telephone (513) 672-8400, fax (513) 672-8422.

FOR FURTHER INFORMATION CONTACT:

Christopher Richards, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: christopher.j.richards@faa.gov; telephone (781) 238-7133; fax (781) 238-7199.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send us any written relevant data, views, or arguments regarding this proposal. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2008-1025; Directorate Identifier 2008-NE-31-AD” in the subject line of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed 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 proposed AD. Using the search function of the Web site, anyone can find and read the comments in any of our dockets, including, if provided, the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78).

Examining the AD Docket

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 proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Operations office (telephone (800) 647-5527) is the same as the Mail address provided in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

Discussion

Since July 2001, GE has reported 12 HPCR spool shaft stage 14 disks with web cracks that were installed in CF6-80C2 and CF6-80E1 series turbofan engines. GE determined that the cracks were caused by defects created during the manufacturing process as a result of high amplitude fatigue (HAF). Although the parts were fluorescent penetrant inspected (FPI) during manufacture, the FPI did not detect the cracks. GE has since revised their manufacturing process to eliminate the HAF. Failure to inspect each affected HPCR spool shaft stage 14 disk web for cracks could result in uncontained failure of the disk and damage to the airplane.

Relevant Service Information

We have reviewed and approved the technical contents of GE Alert Service Bulletin (ASB) No. CF6-80C2 S/B 72-A1122, Revision 1, dated June 19, 2006 (CF6-80C2 series engines), and GE ASB No. CF6-80E1 S/B 72-A0258, Revision 1, dated June 15, 2006 (CF6-80E1 series engines). Those ASBs describe procedures for performing a one-time ECI of the HPCR spool shaft stage 14 disk web for crack indications.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other products of this same type design. We are proposing this AD, which would require, at the next engine shop visit where the separation of a major engine flange will occur, a one-time ECI of the HPCR spool shaft stage 14 disk web for crack indications, and removal from service of parts found cracked. The proposed AD would require you to use the service information described previously to perform these actions.

Costs of Compliance

We estimate that this proposed AD would affect 126 CF6-80C2 and CF6-80E1 series turbofan engines installed on airplanes of U.S. registry. We also estimate that it would take about 10 work-hours per engine to perform the inspection, and about 281 hours to complete the proposed actions if done at module level, and that the average labor rate is $80 per work-hour. The pro-rated cost of a HPCR stage 10-14 spool shaft, based on average life remaining on disks found cracked, is $526,890. Using data on the percentage of the affected fleet already in compliance with the corrective actions, we estimate there will be 10 disks found cracked as a result of these inspections. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to be $594,500.

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.

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would 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 proposed AD:

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. Would 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 regulatory evaluation of the estimated costs to comply with this proposed AD. You may get a copy of this summary at the address listed under ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Incorporation by reference
• Safety

The Proposed Amendment

Under the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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.