85-25-56 R1 GENERAL ELECTRIC COMPANY: Telegram issued December 20, 1985, as amended by Amendment 39-5495. Applies to General Electric Company (GE) CF6-50 and -45 series turbofan engines.
Compliance is required as indicated, unless already accomplished.
To prevent failure of the left hand side seventh stage low pressure turbine (LPT) cooling air manifold tube, which could result in an LPT overtemperature condition and subsequent LPT stage 1 disk rupture, accomplish the following:
(a) For those engines not in compliance with the requirements of GE Service Bulletin (SB) 75-54, dated July 19, 1985, or paragraph 2.A. or 2.B. of GE SB 75-46, Revision 3, dated June 8, 1982, comply with paragraphs (1) then (2) below:
(1) Accomplish the requirements of paragraphs 2.A.1. and 2.A.2. of GE SB 75-55, dated September 13, 1985, concurrently with the requirements of paragraph 2.A. of GE SB 75-54, or FAA approved equivalents, within 10 flight cycles after the effective date ofthis AD.
(2) Accomplish the requirements of paragraph 2. of GE SB 75-55 or FAA approved equivalent, within 60 calendar days of complying with paragraph (1) above.
(b) For engines already in compliance with the requirements of GE SB 75-54 or paragraph 2.A. or 2.B. of GE SB 75-46, accomplish the requirements of paragraph 2. of GE SB 75-55 within 60 calendar days after the effective date of this AD.
(c) Replace cracked, broken or ruptured left hand side seventh stage LPT cooling air manifold tube and attachment hardware, found during accomplishment of paragraph (a) or (b) above, before further flight.
(d) Inspect the left hand side seventh stage LPT cooling air manifold tubes and attachment hardware in accordance with the requirements of paragraphs 2.A., 2.B., 2.C. and 2.D.(4)(b) of GE SB 75-58, dated April 14, 1986, or FAA approved equivalent, within the next 250 flight cycles after the effective date of this AD, and thereafter, at intervals not to exceed 250 flightcycles from the last inspection.
(e) Replace or tighten, in accordance with paragraph 2.D. of GE SB 75-58, left hand side seventh stage LPT cooling air system hardware found worn, loose, cracked or broken during accomplishment of paragraph (d) above, prior to further flight.
Aircraft may be ferried in accordance with the provisions of FAR 21.197 and 21.199 to a base where the AD can be accomplished.
Upon request, an equivalent means of compliance with the requirements of this AD may be approved by the Manager, Engine Certification Office, Aircraft Certification Division, Federal Aviation Administration, New England Region, 12 New England Executive Park, Burlington, Massachusetts 01803.
Upon submission of substantiating data by an owner or operator through an FAA maintenance inspector, the Manager, Engine Certification Office, may adjust the compliance time specified in this AD.
GE SB's 75-54, dated July 19, 1985; 75-46, Revision 3, dated June 8, 1982; 75-55, dated September 13, 1985; and 75-58, dated April 14, 1986, identified and described in this document, are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies, upon request, from General Electric Company, 1 Neumann Way, Cincinnati, Ohio 45215. These documents also may be examined at the Office of the Regional Counsel, Federal Aviation Administration, New England Region, 12 New England Executive Park, Burlington, Massachusetts 01803, Rules Docket Number 85-ANE-44, Room 311, between the hours of 8:00 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays.
Paragraphs (a), (b), and (c) of this amendment become effective January 5, 1987, as to all persons except those persons to whom paragraphs (a), (b), and (c) of this amendment were made immediately effective by TAD T85-25-56, issued December 20, 1985. Paragraphs (d) and (e)of this amendment become effective January 13, 1987, as to all persons.