AD 2000-12-08

This amendment adopts 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 AD requires 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 required. If no cracks are discovered by 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 amendment 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 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.

Final rule.

2000-12-08 General Electric Company: Amendment 39-11786. Docket 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 (e) ofthis 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) Visually inspect aft engine mount link assemblies for separations, cracks, and spherical bearing race migration, as follows:

Not Previously Inspected

(1) 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

(2) 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 November 12, 1999, or Original, dated April 16, 1999,

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

Cracked or Separated Parts

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

(i) Remove the cracked or separated aft engine mount link assembly and the attaching hardware from service; AND

(ii) Replace with serviceable parts.

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

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

(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

(6) 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)

(7) If crack indications are not discovered, within 75 CIS after the inspection performed in accordance with paragraph (a)(5)(ii) of this AD, remove the aft engine mount link assembly from service, and replace with serviceable parts.

Attaching Hardware

(8) 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 includes 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 before 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

(d) 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.
Alternative Methods of Compliance

(e) 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

(f) Special flight permits may be issued in accordance with sections 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.

Incorporation By Reference

(g) The inspection shall be done in accordance with the following GE Alert Service Bulletins: (ASBs) CF6-80C2 72-A0964, Revision 2, dated January 24, 2000; Revision 1, dated November 12, 1999; Original, dated April 16, 1999 and CF6-80C2 72-A0989, dated January 19, 2000. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies 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. Copies may be inspected at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA; or at the Office of the Federal Register, 800 North Capitol Street, NW, suite 700, Washington, DC.

Effective Date

(h) This amendment becomes effective on August 28, 2000.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to General Electric Company Models CF6-80C2A1/A2/A3/A5/A5F/A8/D1F turbofan engines was published in the Federal Register on February 23, 2000 (65 FR 8892). That action proposed to 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 and replacement of cracked or separated parts prior to further flight.

Comments received

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

Link assembly replacement cost

Although one comment agrees with the technical content of the AD, concern was expressed because the economic analysis within the NPRM indicates that the cost to replace link assemblies is approximately $7,000 per engine, while the service bulletin indicates the cost is $9,718 per engine. The comment suggests that the FAA should change its economic analysis to match the cost quoted in the Service Bulletin. The FAA does not agree. The FAA started with the new part costs cited in the service bulletin, but took into account that some useful life had been realized from the existing parts. The $7,000 per engine cost to replace link assemblies quoted in the NPRM represents the cost of the lost life of existing, installed links.

Length of grace period

Another comment requests that the length of the grace period permitted to remove migrated links that are not cracked, be tied to the extent of bearing migration. The FAA does not agree. Bearing migration results from a failed or undersized bearing race swage lip. There is no data available to quantify the rate of migration once the retention feature is overcome. Once migration begins, there is no datato indicate that it will not progress until contact is made with the boss of the turbine rear frame clevis. Therefore, the analysis assumed the worst case condition (i.e. maximum migration) for calculating the reduction in useful life. The 75-cycle allowance for replacement of migrated, but not cracked links, is considered conservative, but reasonable.

Replacement of aft engine mount link assemblies

One comment requests that the FAA change the requirement to replace aft engine mount link assemblies with improved aft engine mount link assemblies by deleting the requirement that link assemblies be replaced prior to the engine accumulating 29,000 cycles since new. The comment stated that link assemblies are sometimes installed new on engines that have already accumulated a considerable number of cycles and that the link assemblies are inspected themselves. Therefore, replacement of link assemblies should not be tied to engine cycles. The FAA does not agree. Links are expected to be replaced "at the next engine shop visit." However, since the current link assemblies are not life-limited and not routinely tracked, the 29,000 cycles since new (CSN) limit was added as an absolute limit. Operators may apply for an Alternate Method of Compliance (AMOC) for link assemblies installed on engines that will exceed the 29,000 CSN limit prior to their next scheduled engine shop visit provided sufficient records of link assembly CSN data are available to show that the links will not exceed 29,000 CSN.

Conclusion

After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed.

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 will be affected by this AD. The cost to replace link assemblies is approximately$7,000. The FAA estimates that it will 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 AD on US operators is estimated to be $2,280,380.

Regulatory Impact

The regulations adopted herein 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. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this action (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 havea significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends 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. 39.13 [Amended]

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