AD 91-12-09

91-12-09 GENERAL ELECTRIC COMPANY: Amendment 39-7020. Docket No. 91-ANE- 11. Applicability: General Electric Company (GE) CF6-6 series turbofan engines installed on, but not limited to, McDonnell Douglas DC10-10 aircraft. Compliance: Required as indicated, unless previously accomplished. To prevent an uncontained engine failure and damage to the aircraft, accomplish the following: (a) Eddy current inspect in accordance with GE CF6-6 Service Bulletin (SB) 72- 947, Revision 4, dated February 8, 1991, the bore forward corner of stage 1 fan disks identified by serial number (S\N) in Tables 2, 3, and 3 Addendum of GE CF6-6 SB 72-947, Revision 4, dated February 8, 1991, as follows: (1) For disks which have not received an eddy current inspection in accordance with the Accomplishment Instructions of GE CF6-6 SB 72-947, Revision 4, dated February 8, 1991, in accordance with the following schedule: (i) Within the next 100 cycles in service (CIS) after the effective date of this AD for those disks which on the effective date of this AD have accumulated 1,250 CIS or greater since accomplishing the immersion ultrasonic inspection of AD 89-20-01 R1, Amendment 39-6411 (54 FR 51015; December 12, 1989). (ii) Within the next 100 CIS after the effective date of this AD or prior to accumulating 1,250 CIS since accomplishing the immersion ultrasonic inspection of AD 89-20-01 R1, whichever comes later for those disks which on the effective date of this AD have accumulated less than 1,250 CIS since the immersion ultrasonic inspection. (2) For those disks which on the effective date of this AD have received an eddy current inspection in accordance with the Accomplishment Instructions of GE CF6-6 SB 72-947, Revision 4, dated February 8, 1991, in accordance with the following schedule: (i) Within the next 100 CIS after the effective date of this AD for those disks which on the effective date of this AD have accumulated 1,500 CIS or greater since accomplishing the immersion ultrasonic inspection of AD 89-20-01 R1. (ii) Within the next 100 CIS after the effective date of this AD or prior to accumulating 1,500 CIS since accomplishing the immersion ultrasonic inspection of AD 89-20-01 R1, whichever comes later, for those disks which on the effective date of this AD have accumulated less than 1,500 CIS since accomplishing the immersion ultrasonic inspection. (b) Thereafter, eddy current inspect the bore forward corner of stage 1 fan disks which meet the acceptance criteria of paragraph 2.B.(2)(c) of the Accomplishment Instructions of GE CF6-6 SB 72-947, Revision 4, dated February 8, 1991, at intervals not to exceed 500 CIS since last eddy current inspection. (c) Remove from service prior to further flight and replace with a serviceable part, disks inspected in accordance with paragraphs (a) and (b) of this AD, which do not meet the acceptance criteria of paragraph 2.B.(2)(c) of the Accomplishment Instructions of GE CF6-6 SB 72-947, Revision 4, dated February 8, 1991. (d) Remove from service all stage 1 fan disks identified by S/N in Tables 2, 3, and 3 Addendum of GE CF6-6 SB 72-947, Revision 4, dated February 8, 1991, at the next shop visit but no later than 2,500 CIS since immersion ultrasonic inspection or June 30, 1992, whichever occurs first. (e) For the purpose of this AD, "shop visit" is defined as the induction of the engine into the shop for any reason. (f) 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. (g) Upon submission of substantiating data by an owner or operator through an FAA (maintenance, avionics, or operations) Inspector, an alternate method of compliance with the requirements of this AD or adjustments to the compliance schedules specified in this AD may be approved by the Manager, Engine Certification Office, Engine and Propeller Directorate, Aircraft Certification Service, FAA, 12 New England Executive Park, Burlington, Massachusetts 01803- 5299. The inspections shall be done in accordance with the following General Electric service document:

Document No. Page No. Issue Date CF6-6 SB 72-947 1 thru 13 Rev. 4 Feb. 8, 1991 Total Pages: 13

This incorporation was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. All persons affected by this directive who have not already received the appropriate service information from the manufacturer may obtain copies upon request to General Electric Company, Technical Publications Department, 1 Neumann Way, Cincinnati, Ohio 45215. This information may be examined at the FAA, New England Region, Office of the Assistant Chief Counsel, Room 311, 12 New England Executive Park, Burlington, Massachusetts 01803-5299. This amendment (39-7020, AD 91-12-09) becomes effective on June 27, 1991.