AD 94-07-04

This amendment adopts a new airworthiness directive (AD), applicable to General Electric Company (GE) CF6-80A series turbofan engines, that requires an inspection for cracks in the stage 1 high pressure turbine (HPT) disk rim bolt holes. This amendment is prompted by a report of an uncontained stage 1 HPT disk failure, which resulted in an aborted takeoff. The actions specified by this AD are intended to prevent an uncontained stage 1 HPT disk failure, which could result in an inflight engine shutdown, aborted takeoff, or damage to the aircraft.

Final rule.

94-07-04 General Electric Company: Amendment 39-8862. Docket 91-ANE-45.
Applicability: General Electric Company (GE) CF6-80A series turbofan engines installed on but not limited to, Boeing 767 series and Airbus A310 series aircraft.
Compliance: Required as indicated, unless accomplished previously.
To prevent an uncontained stage 1 high pressure turbine (HPT) disk failure, which could result in an inflight engine shutdown, rejected takeoff, or damage to the aircraft, accomplish the following:
(a) Eddy current inspect (ECI) for cracks stage 1 HPT disks, Part Numbers (P/N) 9234M67G12, 9234M67G13, 9234M67G14, 9234M67G15, 9234M67G16, 9234M67G22, 9234M67G24, 9367M45G01, 9367M45G02, 9367M45G03, and 9367M45G04, regardless of serial number; and stage 1 HPT disks, P/N 9362M58G02, with serial numbers listed in paragraph 1.A. of GE CF6-80A Service Bulletin (SB) No. 72-604, Revision 3, dated April 8, 1993; in accordance with the accomplishment instructions of GE CF6-80A SB No. 72-604, Revision 3, dated April 8, 1993, as follows:
(1) For disks that have accumulated less than 3,000 cycles since new (CSN) on the effective date of this AD, ECI the rim bolt holes at the next engine shop visit after accumulating 3,000 CSN, but not to exceed 4,500 CSN.
(2) For disks that have accumulated 3,000 CSN or more, but less than 4,000 CSN on the effective date of this AD, ECI the rim bolt holes at the next engine shop visit, but not to exceed 4,500 CSN.
(3) For disks that have accumulated 4,000 CSN or more, but less than 9,500 CSN on the effective date of this AD, ECI the rim bolt holes at the next engine shop visit, or prior to July 20, 1994, whichever occurs earlier.
(4) For disks that have accumulated 9,500 CSN or more on the effective date of this AD, ECI the rim bolt holes at the next engine shop visit.
(b) ECI stage 1 HPT disks, P/N 9362M58G02, with serial numbers not listed in paragraph 1.A. of GE CF6-80A SB No. 72-604, Revision 3, dated April 8, 1993, in accordance with the accomplishment instructions of GE CF6-80A SB No. 72-604, Revision 3, dated April 8, 1993, at the next exposure of the stage 1 HPT disk at the piece part level.
(c) Remove from service disks found cracked, and replace with serviceable parts. Inspect replacement disks in accordance with paragraph (a) or (b) of this AD, if applicable.
(d) Disks referenced in paragraph (a) or (b) of this AD that have been inspected in accordance with Commercial Engine Service Memorandum No. 27, dated September 27, 1991, or any revision level of GE CF6-80A SB No. 72-604, prior to the effective date of this AD, and whose CSN at the time of inspection was 3,000 or more, meet the inspection requirements of paragraph (a) and (b) of this AD.
(e) For the purpose of this AD, an engine shop visit is defined as the induction of an engine into a shop for maintenance involving the separation of any major flange.
(f) An alternative method of compliance or adjustment of the initialcompliance time that provides an acceptable level of safety may be used if approved by the Manager, Engine Certification Office. The request should be forwarded through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Engine Certification Office. NOTE: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Engine Certification Office.
(g) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate the aircraft to a location where the requirements of this AD can be accomplished.
(h) The inspection, and replacement, if necessary, shall be done in accordance with the following service bulletin:

Document No.
Pages
Revision
Date
GE CF6-80A SB
No. 72-604

1

3

April 8, 1993

2
2
July 2, 1992

3
3
April 8, 1993

4-12
2
July 2, 1992
Total Pages: 12.

Thisincorporation 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 Aircraft Engines, CF6 Distribution Clerk, Room 132, 111 Merchant Street, Cincinnati, OH 45246. Copies may be inspected at the FAA, New England Region, Office of the Assistant Chief 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.
(i) This amendment becomes effective on May 23, 1994.

A proposal to amend part 39 of the Federal Aviation Regulations to include an airworthiness directive (AD) that is applicable to General Electric Company (GE) CF6- 80A series turbofan engines was published as a notice of proposed rulemaking (NPRM) in the Federal Register on January 9, 1992 (57 FR 857). That action proposed to require a one-time inspection for cracks in the stage 1 high pressure turbine (HPT) disk rim bolt holes in accordance with GE Commercial Engine Service Memorandum (CESM) No. 27, dated September 27, 1991.

Since the issuance of that NPRM, GE issued CF6-80A Service Bulletin (SB) No. 72-604, Revision 3, dated April 8, 1993, which revised the inspection program based on additional investigation findings on the reported disk failure. A Supplemental NPRM was published in the Federal Register on November 3, 1993 (58 FR 58667), which proposed to require an inspection for cracks in the stage 1 HPT disk rim bolt holes in accordance with the revised inspection program described in GE CF6-80A SB No. 72-604, Revision 3, dated April 8, 1993.

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

One commenter supports the rule as proposed.

One commenter states that previous revision levels of GE CF6-80A SB No. 72-604, Revision 3, dated April 8, 1993, should be incorporated by reference. The FAA does not concur. Compliance paragraph (d) of the proposed rule already addresses inspections performed in accordance with these previous revision levels.

One commenter states that the AD should not refer to a specific revision of the GE SB, but instead, use the phrase "latest revision" when citing the SB. The FAA does not concur. When incorporating a manufacturer's SB into an AD, the actual revision level and issue date of the SB must be specified. The FAA can not review and approve the technical contents of a document that has not yet been issued. Future revisions to a SB incorporated into an AD that do not substantively change the compliance requirements or times, may carry FAA approval as alternate methods of compliance to allow operators the greatest flexibility in performing the requirements of an AD.

One commenter states that the inspection thresholds should be based on cycles since new on the issuance of GE CF6-80A SB No. 72-604, Revision 2, dated July 2, 1992, rather than the effective date of the AD to be consistent with their current inspection program. The FAA does not concur. This recommendation might cause an undue burden to another operator based on the anticipated publication date of this amendment.

The FAA has determined that the compliance end date of December 31, 1993, noted in compliance paragraph (a)(3) of the NPRM, is inconsistent with the anticipated publication date of this amendment, and as such may place undue burden on operators. The NPRM proposed a compliance period of 60 days to accomplish the required actions based on the anticipated publication date of the AD at the time the NPRM was published. Therefore, the compliance end date in compliance paragraph (a)(3) of this final rule has been revised to 90 days after date of publication in the Federal Register. This time period is comprised of the 30 day period after publication and prior to the effective date plus 60 days.

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 with the change described previously. The FAA has determined that this change will neither increase the economic burden on any operator nor increase the scope of the AD.

There are approximately 154 GE CF6-80A series engines of the affected design in the worldwide fleet. The FAA estimates that 48 engines installed on aircraft of U.S. registry will be affected by this AD, that it will take approximately 232 work hours per engine to accomplish the required actions, and that the average labor rate is $55 per work hour. Required parts will cost approximately $172,800 per engine. Based on these figures, and assuming all inspected disks require replacement, the total cost impact of the AD on U.S. operators is estimated to be $8,906,880.

The regulations adopted herein will not have substantial direct effects 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, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

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 DOTRegulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) 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 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 14 CFR part 39 of the Federal Aviation Regulations as follows:

PART 39 - AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.

39.13 - [AMENDED]
2. Section 39.13 is amended by adding the following new airworthiness directive: