AD 95-08-03

This amendment adopts a new airworthiness directive (AD), applicable to General Electric Company (GE) CF6-45/-50 series turbofan engines, that requires reduction of the low cycle fatigue (LCF) retirement lives for certain high pressure turbine rotor (HPTR) stage 2 disks, and would provide a drawdown schedule for those affected parts with reduced LCF retirement lives. This amendment is prompted by the results of a refined life analysis performed by the manufacturer which revealed minimum calculated LCF lives significantly lower than published LCF retirement lives. The actions specified by this AD are intended to prevent a LCF failure of the HPTR stage 2 disk, which could result in an uncontained engine failure and damage to the aircraft.

Final rule.

95-08-03 General Electric Company: Amendment 39-9192. Docket 94-ANE-37.

Applicability: General Electric Company (GE) CF6-45/-50 series turbofan engines installed on but not limited to Airbus A300 series, Boeing 747 series, and McDonnell Douglas DC-10 series aircraft.

NOTE: This 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 use the authority provided in paragraph (e) to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition, or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any engine from the applicability of this AD.

Compliance: Required as indicated, unless accomplished previously.

To prevent a low cycle fatigue (LCF) failure of the high pressure turbine rotor (HPTR) stage 2 disk, which could result in an uncontained engine failure and damage to the aircraft, accomplish the following:

(a) Remove from service HPTR stage 2 disks Part Numbers (P/N) 1474M49P04, 1474M49P05, 1474M49P06, 9045M35P15, 9045M35P17, and 9045M35P18, in accordance with the following:

(1) For disks that have accumulated less than 3,500 cycles since new (CSN) on the effective date of this airworthiness directive (AD), remove disk from service prior to accumulating 7,080 CSN.

(2) For disks that have accumulated 3,500 CSN or more, but less than 7,080 CSN on the effective date of this AD, remove disk from service prior to accumulating 7,080 CSN, or prior to accumulating 3,100 cycles in service (CIS) after the effective date of this AD, whichever occurs later, but not to exceed 9,700 CSN.

(3) For disks which have accumulated 7,080 CSN or more on the effective date of this AD, remove disk from service at the next piece-part exposure, but not to exceed 9,700 CSN.

(b) Remove from service HPTR stage 2 disks P/N 9264M58P01, 9264M58P02, and 9264M58P03 prior to accumulating 7,080 CSN.

(c) This AD establishes the following new LCF retirement lives which will be published in Chapter 5 of the CF6-50 Engine Task Numbered Shop Manual, GEK 50481: 7,080 cycles for HPTR stage 2 disk P/N 1474M49P04, 1474M49P05, 1474M49P06, 9045M35P15, 9045M35P17, 9045M35P18, 9264M58P01, 9264M58P02, and 9264M58P03.

(d) GE CF6-50 Service Bulletin (SB) No. 72-1069, dated September 12, 1994, describes an FAA-approved rework procedure for the affected disks. Accomplishment of this rework increases the FAA-approved LCF retirement lifeto 8,750 or 9,700 cycles, depending on the CSN of the disk when the rework is performed.

(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. 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.

(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 requirements of this AD can be accomplished.

(g) The actions required by this AD shall be done in accordance with the following service bulletin:Document No.
Pages
Date
GE CF6-50 SB
No. 72-1069
1-18
September 12, 1994
Total Pages: 18

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 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.

(g) This amendment becomes effective on June 12, 1995.

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 (GE) CF6-45/-50 series turbofan engines was published in the Federal Register on December 20, 1994 (59 FR 65513). That action proposed to require a reduction of the published low cycle fatigue (LCF) retirement lives for certain high pressure turbine rotor stage 2 disks, and would provide a drawdown schedule for those affected disks with reduced LCF retirement lives. If the Federal Aviation Administration (FAA)-approved rework is accomplished, the LCF retirement life may be increased to 8,750 or 9,700 cycles, depending on the cycles since new of the disk when the rework is performed. The actions would be performed in accordance with GE CF6-50 Service Bulletin No. 72-1069, dated September 12, 1994.
Interested persons have been afforded an opportunity to participate in the making of thisamendment. Due consideration has been given to the comments received.
Two commenters support the rule as proposed.
Since publication of the NPRM, the FAA has increased its estimate of the average labor cost to $60 per work hour, and has revised the economic analysis of this final rule accordingly.
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 with the changes described previously. The FAA has determined that these changes will not increase the scope of the AD.
The FAA estimates that 280 engines installed on aircraft of U.S. registry will be affected by this AD, that it will take approximately 194 work hours per engine to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will cost approximately $16,383 per engine. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $7,846,440.
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 DOT Regulatory 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 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. 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: