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Proposed Rule

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

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Information about this document as published in the Federal Register.

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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.

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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.

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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 Start Printed Page 8893require 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.

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List of Subjects in 14 CFR Part 39

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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:

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PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

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Authority: 49 U.S.C. 106(g), 40113, 44701.

End Authority
[Amended]

2. Section 39.13 is amended by adding the following new airworthiness directive:

General Electric Company: Docket No. 99-NE-45-AD.

Applicability: General Electric Company (GE) Models CF6-80C2A1/A2/A3/A5/A5F/A8/D1F turbofan engines, with left hand aft engine mount link assemblies, part numbers (P/Ns) 9348M79G01 or 9348M79G02 installed, or right hand aft engine mount link assemblies, P/Ns 9348M84G01 or 9348M84G02 installed. These engines are installed on but not limited to Airbus Industrie A300 and A310 series, and McDonnell Douglas MD-11 series aircraft.

Note 1:

This airworthiness directive (AD) applies to each engine identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For engines that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (d) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

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, accomplish the following:

Initial Inspection

(a) Inspect aft engine mount link assemblies as follows:

Not Previously Inspected

  • Within 400 cycles-in-service (CIS) after the effective date of this AD, if not previously inspected using GE CF6-80C2 Alert Service Bulletin (ASB) 72-A0964, Revision 2, dated January 24, 2000, Revision 1, dated November 12, 1999, or Original, dated April 16, 1999, or

Previously Inspected

  • Within 400 cycles-since-last-inspection (CSLI), if previously inspected using GE CF6-80C2 Alert Service Bulletin (ASB) 72-A0964, Revision 2, dated January 24, 2000, Revision 1, dated Month Day, Year, or Original, dated Month Day, Year, GE CF6-80C2 ASB 72-A0964, Revision 2, dated January 24, 2000.

(1) Visually inspect for:

  • Separations,
  • Cracks, and
  • Spherical bearing race migration.

(2) Inspect in accordance with the Accomplishment Instructions of GE CF6-80C2 ASB 72-A0964, Revision 2, dated January 24, 2000.

Cracked or Separated Parts

(3) If a crack or separation is discovered, prior to further flight:

  • Remove the cracked or separated aft engine mount link assembly and the attaching hardware from service, and
  • Replace with serviceable parts.

Removal of Aft Engine Mount Link Assemblies With Spherical Bearing Race Migration

(4) If an aft engine mount link assembly is found with spherical bearing race migration, but no cracks or separations, prior to further flight, either

Removal

(i) Remove the aft engine mount link assembly and the attaching hardware from service and replace with serviceable parts, or

Additional Borescope Inspection of Aft Engine Mount Link Assemblies With Spherical Bearing Race Migration

(ii) Perform an additional borescope inspection for cracks in accordance with paragraph (3)(I) of the Accomplishment Instructions of GE CF6-80C2 ASB 72-A0964, Revision 2, dated January 24, 2000.

After Additional Borescope Inspection, if Parts Are Cracked

(A) If a crack indication is discovered, prior to further flight,

  • Remove the cracked aft engine mount link assembly and the attaching hardware from service, and
  • Replace with serviceable parts.

After Additional Borescope Inspection, if Parts Are Not Cracked (Grace Period)

(B) If crack indications are not discovered, within 75 CIS after the inspection performed in accordance with paragraph (a)(4)(ii) of this AD: Start Printed Page 8894

  • Remove the aft engine mount link assembly from service, and
  • Replace with serviceable parts.

Attaching Hardware

(iii) Attaching hardware may be returned to service after inspection in accordance with paragraph 3(I)(1)(d) or 3(I)(2)(d) of GE CF6-80C2 ASB 72-A0964, Revision 2, dated January 24, 2000, as applicable, only if visual inspection of the removed link shows no cracks or separations.

Note 2:

Link attaching hardware include the nuts, bolts and washers that secure the link.

Repetitive Inspections

(b) Thereafter, perform the actions required by paragraph (a) and associated subparagraphs at intervals not to exceed 400 CSLI.

Replacement With Improved Link Assemblies

(c) Replace aft engine mount link assemblies with improved aft engine mount link assemblies at:

  • The next engine shop visit (ESV), or
  • Prior to accumulating 29,000 engine cycles since new (CSN), whichever occurs first.

(1) Replace in accordance with the Accomplishment Instructions of CF6-80C2 ASB 72-A0989, dated January 19, 2000.

Left Hand Aft Engine Mount Link Assemblies

(2) Replace left-hand aft engine mount link assemblies, P/Ns 9348M79G01 or 9348M79G02, with improved left-hand aft engine mount link assemblies, P/N 1846M23G01.

Right Hand Aft Engine Mount Link Assemblies

(3) Replace right hand aft engine mount link assemblies, P/Ns 9348M84G01 or 9348M84G02, with improved right hand aft engine mount link assemblies, P/N 9348M84G03.

Terminating Action

(4) Installation of improved aft engine mount link assemblies in accordance with paragraph (c) and its subparagraphs constitutes terminating action to the inspections required by paragraphs (a) and (b) of this AD.

Alternate Methods of Compliance

(d) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Engine Certification Office. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Engine Certification Office.

Note 3:

Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Engine Certification Office.

Ferry Flights

(e) Special flight permits may be issued in accordance with §§ 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the aircraft to a location where the inspection requirements of this AD can be accomplished.

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Issued in Burlington, Massachusetts, on February 15, 2000.

David A. Downey,

Assistant Manager, Engine and Propeller Directorate, Aircraft Certification Service.

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[FR Doc. 00-4263 Filed 2-22-00; 8:45 am]

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