Airworthiness Directives; General Electric Company Models CF6-80C2A1/A2/A3/A5/A5F/A8/D1F Turbofan Engines

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to General Electric Company (GE) Models CF6-80C2A1/A2/A3/A5/A5F/A8/D1F turbofan engines. This proposal would require initial and repetitive visual inspections of left hand and right hand aft engine mount link assemblies for separations, cracks and spherical bearing race migration. Cracked or separated parts must be replaced prior to further flight. If spherical bearing race migration is discovered, an additional borescope inspection for cracks is also proposed. If no cracks are discovered in the additional borescope inspection, assemblies have a 75-cycle grace period for remaining in service before replacement. Finally, installation of improved aft engine mount link assemblies constitutes terminating action to the inspections of this AD. This proposal is prompted by a report of a fractured left-hand aft engine mount link discovered during a scheduled removal of an engine of similar design. The actions specified by the proposed AD are intended to prevent aft engine mount link failure, which can result in adverse redistribution of the aft engine mount loads and possible aft engine mount system failure.

DATES:

Comments must be received by April 24, 2000.

ADDRESSES:

Submit comments to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 99-NE-45-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may also be sent via the Internet using the following address: “9-ane-adcomment@faa.gov”. Comments sent via the Internet must contain the docket number in the subject line. Comments may be inspected at this location between 8 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays.

The service information referenced in the proposed rule may be obtained 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. This information may be examined at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA.

FOR FURTHER INFORMATION CONTACT:

William S. Ricci, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone 781-238-7742, fax 781-238-7199.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 99-NE-45-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 99-NE-45-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

In September 1997, the Federal Aviation Administration (FAA) received a report of a fractured General Electric Company (GE) CF6-80A3 series aft engine mount link found during a scheduled engine removal on an Airbus Industrie A310 series aircraft. Recent inspections revealed migrated spherical bearing races on two CF6-80A3 series and ten CF6-80C2 series aft engine mount links. Aft engine mount link spherical bearing race migration adversely affects link fatigue life. This condition, if not corrected, could result in aft engine mount link failure, which can result in adverse redistribution of the aft engine mount loads and possible aft engine mount system failure.

Service Information

The FAA has reviewed and approved the technical contents of GE CF6-80C2 Alert Service Bulletin (ASB) 72-A0989, dated January 19, 2000, that describes the aft engine mount link replacement. The FAA has also reviewed and approved the technical contents of GE CF6-80C2 ASB 72-A0964, Revision 2, dated January 24, 2000, that describes procedures for visual inspections of existing left hand and right hand aft engine mount link assemblies for separations, cracks, and spherical bearing race migration, and provides rejection criteria.

Proposed Actions

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would require initial and repetitive visual inspections of left hand and right hand aft engine mount link assemblies for separations, cracks, and spherical bearing race migration. If spherical bearing race migration is discovered, a borescope inspection for cracks is also proposed. Aft engine mount link assemblies found cracked or separated must be replaced with serviceable parts prior to further flight. Aft engine mount link assemblies discovered with spherical bearing race migration may remain in service for another 75 cycles-in-service (CIS) following borescope inspection prior to replacement with serviceable parts. Finally, this AD would require the replacement of left hand and right hand aft engine mount link assemblies with improved design assemblies at the next engine shop visit, or prior to accumulating 29,000 engine cycles since new (CSN), whichever occurs first. Replacing the assemblies would constitute terminating action to the repetitive inspections. These actions would be required to be accomplished in accordance with the ASBs described previously.

Economic Analysis

There are approximately 975 engines of the affected design in the worldwide fleet. The FAA estimates that 323 engines installed on aircraft of US registry would be affected by this proposed AD. The cost to replace link assemblies is approximately $7,000. The FAA estimates that it would take approximately 0.5 work hours per engine to accomplish each of an average of two interim inspections prior to next engine shop visit and that the average labor rate is $60 per work hour. Based on these figures, the total cost impact of the proposed AD on US operators is estimated to be $2,280,380.

Regulatory Impact

The regulations proposed herein 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. Therefore, it is determined that this proposed rule does not have federalism implications under Executive Order (EO) No.13132.

For the reasons discussed above, I certify that this proposed regulation (1) is not a “significant regulatory action” under EO No. 12866; (2) is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, 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. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (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.