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AD 95-03-01

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Airworthiness directive · Airworthiness Directives; General Electric Company CF6 Series Turbofan Engines

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Effective
March 20, 1995
Published
February 16, 1995 · 60 FR 8930–8932
Amendment
39-9138
Docket
94-ANE-11
Issued as
Final rule

Unofficial copy from the Federal Register text, document 95-3248. Only the govinfo PDF is the legal edition.

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Summary

This amendment supersedes an existing airworthiness directive (AD), applicable to General Electric Company (GE) CF6-45/-50/-80A series turbofan engines, that currently requires a one-time ultrasonic and eddy current inspection of the high pressure compressor rotor (HPCR) stage 3-9 spool for cracks. This amendment retains the inspection requirements of the current AD, but would accelerate the inspection schedule, and introduce a repetitive inspection requirement. This amendment is prompted by a review of the inspection results to date, which indicate that the crack occurrence rate is higher than initially projected. The actions specified by this AD are intended to prevent an uncontained HPCR stage 3-9 spool failure, which could result in damage to the aircraft.

The airworthiness directive

95-03-01 General Electric Company: Amendment 39-9138. Docket 94-ANE-11. Supersedes AD 91-20-01, Amendment 39-8035.

Sec. 39.13 [AMENDED]

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2. Section 39.13 is amended by removing Amendment 39-8035 (56 FR 55230; October 25, 1991) and by adding a new airworthiness directive to read as follows:

Applicability: General Electric Company (GE) CF6-45/-50/-80A series turbofan engines installed on, but not limited to, Airbus A300 and A310 series, Boeing 747 and 767 series, and McDonnell Douglas DC-10 series aircraft.

Compliance: Required as indicated, unless accomplished previously.

To prevent an uncontained high pressure compressor rotor (HPCR) stage 3-9 spool failure, which could result in damage to the aircraft, accomplish the following:

(a)

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(a) Eddy current and ultrasonic inspect GE CF6-45/-50 HPCR stage 3-9 spools, Part Number (P/N) 9136M89G02, 9136M89G03, 9136M89G06, 9136M89G08, 9253M85G01, 9253M85G02, 9273M14G01, and 9331M29G01, with serial numbers (S/N) listed in Table 2 of GE CF6-50 Service Bulletin (SB) No. 72-1000, Revision 2, dated September 9, 1993, as follows:

(1) For spools that have not been previously inspected in accordance with GE CF6-50 SB No. 72-888, Original, Revision 1, Revision 2, Revision 3, or Revision 4, or GE CF6-50 SB No. 72-1000, Original, Revision 1, or Revision 2, inspect in accordance with paragraph 2.C of GE CF6-50 SB No. 72-1000, Revision 2, dated September 9, 1993, at the next engine shop visit, or by 30 days after the effective date of this AD, whichever occurs earlier.

(2) For spools that have been inspected in accordance with GE CF6-50 SB No. 72-888, Original, Revision 1, or Revision 2, inspect in accordance with paragraph 2.D of GE CF6-50 SB No. 72-1000, Revision 2, dated September 9, 1993, at the next engine shop visit, or by 30 days after the effective date of this AD, whichever occurs earlier.

(3) For spools that have been inspected in accordance with GE CF6-50 SB No. 72-888, Original, Revision 1, or Revision 2, and GE CF6-50 SB No. 72-1008, Original, inspect in accordance with paragraph 2.D of GE CF6-50 SB No. 72-1000, Revision 2, dated September 9, 1993, at the next piece-part exposure, or within 4,000 cycles in service (CIS) since inspected in accordance with GE CF6-50 SB No. 72-1008, Original, whichever occurs earlier.

(4) For spools that have been inspected in accordance with GE CF6-50 SB No. 72-888, Revision 3, or Revision 4, or GE CF6-50 SB No. 72-1000, Original, Revision 1, or Revision 2, inspect in accordance with paragraph 2.D of GE CF6-50 SB No. 72-1000, Revision 2, dated September 9, 1993, at the next piece-part exposure, or within 4,000 CIS since inspected in accordance with, GE CF6-50 SB No. 72-888, Revision 3, or Revision 4, or GE CF6-50 SB No. 72-1000, Original, Revision 1, or Revision 2, whichever occurs earlier.

(b)

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(b) Thereafter, for spools that have been inspected in accordance with paragraph (a) of this AD, reinspect in accordance with paragraph 2.D of GE CF6-50 SB No. 72-1000, Revision 2, dated September 9, 1993, at intervals not to exceed 4,000 CIS since the last inspection.

(c)

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(c) Eddy current and ultrasonic inspect GE CF6-80A HPCR 3-9 spool, P/N 9136M89G10, with S/N's listed in Table 2 of GE CF6-80A SB No. 72-583, Revision 4, dated September 15, 1993, as follows:

(1) For spools that have not been previously inspected in accordance with GE CF6-80A SB No. 72-500, Original, Revision 1, Revision 2, Revision 3, or Revision 4, or GE CF6-80A SB No. 72-583, Original, Revision 1, Revision 2, Revision 3, or Revision 4, inspect in accordance with paragraph 2.C of GE CF6-80A SB No. 72-583, Revision 4, dated September 15, 1993, at the next engine shop visit, or by 30 days after the effective date of this AD, whichever occurs earlier.

(2) For spools that have been previously inspected in accordance with GE CF6-80A SB No. 72-500, Revision 3, or Revision 4, or GE CF6-80A SB No. 72-583, Original, Revision 1, Revision 2, Revision 3, or Revision 4, inspect in accordance with paragraph 2.D of GE CF6-80A SB No. 72-583, Revision 4, dated September 15, 1993, at the next piece-part exposure, or within 4,000 CIS since inspected in accordance with GE CF6-80A SB No. 72-500, Revision 3, or Revision 4, or GE CF6-80A SB No. 72-583, Original, Revision 1, Revision 2, Revision 3, or Revision 4, whichever occurs earlier.

(d)

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(d) Thereafter, for spools that have been inspected in accordance with paragraph (c) of this AD, reinspect in accordance with paragraph 2.D of GE CF6-80A SB No. 72-583, Revision 4, dated September 15, 1993, at intervals not to exceed 4,000 CIS since the last inspection.

(e)

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(e) Remove from service prior to further flight HPCR stage 3-9 spools that meet or exceed the reject criteria established in Section 2.C and 2.D, as applicable, of GE CF6-50 SB No. 72-1000, Revision 2, dated September 9, 1993, and GE CF6-80A SB No. 72-583, Revision 4, dated September 15, 1993, as appropriate.

(f)

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(f) For the purpose of this AD, an engine shop visit is defined as the induction of an [[Page 8932]] engine into a shop for maintenance involving the separation of any major flange.

(g)

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(g) For the purpose of this AD, piece-part exposure is defined as disassembly and removal of the stage 3-9 spool from the HPCR rotor.

(h)

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(h) 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 method of compliance with this AD, if any, may be obtained from the Engine Certification Office.

(i)

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(i) 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.

(j)

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(j) The actions required by this AD shall be done in accordance with the following service bulletins:

------------------------------------------------------------------------ Document No. Pages Revision Date ------------------------------------------------------------------------ GE CF6-50, SB No. 72-1000... 1-37 2 Sept. 9, 1993. Total pages: 37....... GE CF6-80A SB No. 72-583.... 1-34 4 Sept. 15, 1993. Total pages: 34....... ------------------------------------------------------------------------

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.

(k)

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(k) This amendment becomes effective on March 20, 1995.

Issued in Burlington, Massachusetts, on January 31, 1995.

Donald F. Perrault, Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.

Rule preamble

The FAA’s background, reasoning and cost estimate, published with the AD.

DatesPage 1

Effective March 20, 1995.

The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of March 20, 1995.

AddressesPage 1

The service information referenced in this AD may be obtained from General Electric Aircraft Engines, CF6 Distribution Clerk, Room 132, 111 Merchant Street, Cincinnati, OH 45246. This information may be examined at the Federal Aviation Administration (FAA), New England Region, Office of the Assistant Chief Counsel, 12 New England Executive Park, Burlington, MA 01803-5299; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

For further information contactPage 1

Robert J. Ganley, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (617) 238-7138; fax (617) 238-7199.

Supplementary informationPage 1

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding airworthiness directive (AD) 91-20-01, Amendment 39-8035 (56 FR 55230), which is applicable to General Electric Company (GE) CF6-45/-50/-80A series turbofan engines, was published in the Federal Register on May 3, 1994 (59 FR 22769). That action proposed to retain the one-time ultrasonic and eddy current inspection of the high pressure compressor rotor (HPCR) stage 3-9 spool for cracks as required in the current AD, but would accelerate the inspection schedule, and introduce a repetitive ultrasonic and eddy current inspection requirement in accordance with GE CF6-50 Service Bulletin (SB) No. 72-1000, Revision 2, dated September 9, 1993, and GE CF6-80A SB No. 72-583, Revision 4, dated September 15, 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.

Two commenters support the rule as proposed.

One commenter states that the repetitive inspection interval of 3,500 cycles in service (CIS) in compliance paragraph (b) of the proposed rule should be replaced with 4,000 CIS in [[Page 8931]] order to avoid premature engine removals. The FAA concurs that this change will avoid some engine removals while not decreasing the level of safety provided by the proposed rule. Accordingly, the FAA has made this change in the final rule.

Although no comments were received regarding compliance paragraphs (a)(3), (a)(4), (c)(2), and (d), the FAA has replaced 3,500 CIS with 4,000 CIS in these paragraphs to maintain consistency.

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

There are approximately 462 GE CF6-45/-50/-80A series engines of the affected design in the worldwide fleet. The FAA estimates that 67 engines installed on aircraft of U.S. registry will be affected by this AD, that it will take approximately 584 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 $127,412 per engine. Based on these figures, and assuming that 3 of the inspected spools will require replacement, the total cost impact of the AD on U.S. operators is estimated to be $2,534,276.

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 39Page 1

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

Adoption of the AmendmentPage 1

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:

Adoption of the amendmentPage 1

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.