Airworthiness Directives; GE Aircraft Engines (GE) CF34-3A, CF34-3A2, CF34-1A, CF34-3A1, CF34-3B, and CF34-3B1 Series Turbofan Engines

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for GE CF34-3A, CF34-3A2, CF34-1A, CF34-3A1, CF34-3B, and CF34-3B1 series turbofan engines. This proposed AD would require removal from service of certain high pressure compressor (HPC) forward spools, at the first piece-part level exposure after 6,000 cycles since new (CSN), but not later than 20,000 CSN for CF34-3B engines and 22,000 CSN for CF34-3A, CF34-3A2, CF34-1A, CF34-3A1, and CF34-3B1 engines. This proposed AD results from an updated low-cycle fatigue (LCF) analysis performed on certain HPC forward spools. We are proposing this AD to prevent LCF cracks and failure of the HPC forward spool, which could result in an uncontained engine failure and damage to the airplane.

DATES:

We must receive any comments on this proposed AD by July 19, 2004.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD:

• By mail: Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 2003-NE-67-AD, 12 New England Executive Park, Burlington, MA 01803-5299.
• By fax: (781) 238-7055.
• By e-mail: 9-ane-adcomment@faa.gov.

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.

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

FOR FURTHER INFORMATION CONTACT:

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.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any written relevant data, views, or arguments regarding this proposal. Send your comments to an address listed under ADDRESSES. Include “AD Docket No. 2003-NE-67-AD” in the subject line of your comments. If you want us to acknowledge receipt of your mailed comments, send us a self-addressed, stamped postcard with the docket number written on it; we will date-stamp your postcard and mail it back to you. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. If a person contacts us verbally, and that contact relates to a substantive part of this proposed AD, we will summarize the contact and place the summary in the docket. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.

We are reviewing the writing style we currently use in regulatory documents. We are interested in your comments on whether the style of this document is clear, and your suggestions to improve the clarity of our communications that affect you. You can get more information about plain language at http://www.faa.gov/language and http://www.plainlanguage.gov.

Examining the AD Docket

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.

Discussion

In October 2003, GE made the FAA aware of its updated LCF analysis of HPC forward spools, P/Ns 6078T56P03 and 6078T56P04, used in CF34-3A, CF34-3A2, CF34-1A, CF34-3A1, CF34-3B, CF34-3B1 turbofan engines. HPC forward spools, P/Ns 6078T56P03 and 6078T56P04, installed in CF34-3A, CF34-3A2, CF34-1A, CF34-3A1, and CF34-3B1 turbofan engines, must be replaced before accumulating 22,000 CSN. The highest time HPC forward spool has accumulated fewer than 21,500 CSN in CF34-3A, CF34-3A2, CF34-1A, CF34-3A1, or CF34-3B1 turbofan engines, to date.

HPC forward spools, P/Ns 6078T56P03 and 6078T56P04, installed in CF34-3B engines, must be replaced before accumulating 20,000 CSN. The highest time HPC forward spool has accumulated fewer than 4,500 CSN in a CF34-3B engine, to date.

We are proposing this AD to prevent LCF cracks and failure of the HPC forward spool, which could result in an uncontained engine failure and damage to the airplane.

Relevant Service Information

We have reviewed and approved the technical contents of GE Alert Service Bulletins (ASBs) No. 72-A0165 and No. 72-A0140, that describe procedures for disassembly and replacement of HPC compressor rotor spool stages 3-8.

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 replacing HPC forward spools, P/Ns 6078T56P03 and 6078T56P04, before accumulating 22,000 CSN on CF34-3A, CF34-3A2, CF34-1A, CF34-3A1, and CF34-3B1 engines, and 20,000 CSN on CF34-3B engines.

Costs of Compliance

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 proposed 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 proposed actions, and that the average labor rate is $65 per work hour. Required parts would 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 proposed AD to U.S. operators to be $74,420,000.

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 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. 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 summary of the costs to comply with this proposal 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.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, 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.