AD 96-26-52 Airworthiness Directives; Boeing Model 747 Series Airplanes

Models named: 747 series, PW4000 series, CF6-80C2 series, RB211 series. Read the applicability below — it usually turns on serial or part numbers too.

Model 747 series airplanes having line numbers 1 through 1046 inclusive; certificated in any category; that meet all of the following criteria: Equipped with Pratt & Whitney Model PW4000 series engines, or General Electric Model CF6-80C2 series engines, or Rolls Royce Model RB211 series engines; On which fuse pins having part numbers 310U2301-101, - 116, -117, or -120 (``third generation'' fuse pins) are installed at the midspar/spring beam fittings of the engine pylon; and On which the modification of the nacelle strut and wing structure in accordance with Boeing Alert Service Bulletin 747- 54A2156 or Boeing Alert Service Bulletin 747-54A2157, as applicable, has not been accomplished. Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Required as indicated, unless accomplished previously. To prevent failure of the engine pylon and consequent separation of the engine from the wing, due to migration of the fuse pins installed at the midspar/spring beam fittings of the pylon, accomplish the following: (a) Within 15 days after January 8, 1997 (the effective date of AD 96-26-52, amendment 39-9868), accomplish the requirements of paragraphs (a)(1) and (a)(2) of this AD. (1) Perform a detailed visual inspection of the access doors to each midspar/spring beam fuse pin on each engine pylon to detect cracks on the external surface of the doors. (i) If no cracking is detected during the inspection, repeat that inspection at intervals not to exceed 1,000 landings or 5,000 hours time-in-service, whichever occurs later, but not to exceed 18 months. (ii) If any cracking is detected during the inspection, prior to further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Thereafter, repeat the inspection at intervals not to exceed 1,000 landings or 5,000 hours time-in-service, whichever occurs later, but not to exceed 18 months. (2) Gain access through the aft fairing doors of each engine pylon to each midspar/spring beam fuse pin and its mating, self- locking nut, and perform a detailed visual inspection of each fuse pin to verify that at least one thread of the fuse pin protrudes beyond its mating, self-locking nut. (i) If no discrepancy is detected during the inspection, repeat that inspection at intervals not to exceed 1,000 landings or 5,000 hours time-in-service, whichever occurs later, but not to exceed 18 months. (ii) If the inspection reveals that at least one thread does not protrude beyond its mating, self-locking nut, prior to further flight, repair in accordance with a method approved by the Manager, Seattle ACO. Thereafter, repeat the inspection at intervals not to exceed 1,000 landings or 5,000 hours time-in-service, whichever occurs later, but not to exceed 18 months. (b) Accomplishment of the modification of the nacelle strut and wing structure in accordance with Boeing Alert Service Bulletin 747- 54A2156, Revision 2, dated December 21, 1995, or earlier revisions (for airplanes equipped with General Electric Model CF6-80C2 series engines, or Pratt & Whitney PW4000 series engines); or Boeing [[Page 26383]] Alert Service Bulletin 747-54A2157, Revision 2, dated November 14, 1996, or earlier revisions (for airplanes with Rolls Royce Model RB211 series engines); as applicable; constitutes terminating action for the repetitive detailed visual inspections required by paragraphs (a)(1) and (a)(2) of this AD. (c) 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, Seattle ACO. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO. Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. (d) 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 airplane to a location where the requirements of this AD can be accomplished. (e) This amendment becomes effective on June 18, 1997. Issued in Renton, Washington, on May 8, 1997. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 97-12682 Filed 5-13-97; 8:45 am] BILLING CODE 4910-13-U