2001-12-23: Vertical Chords of the Aft Torque Bulkhead of the Outboard Nacelle Struts

2001-12-23 Boeing: Amendment 39-12279. Docket 2000-NM-354-AD. Supersedes AD 2000-23-25, Amendment 39-11998. \n\n\tApplicability: Model 747-100, 747-200, 747-300, 747SP, and 747SR series airplanes powered by Pratt & Whitney JT9D-3 or JT9D-7 series engines; as listed in Boeing Alert Service Bulletin 747-54A2201, dated September 28, 2000; certificated in any category. \n\n\tNote 1: This AD applies to each airplane 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 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 (e) 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 unsafecondition has not been eliminated, the request should include specific proposed actions to address it. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo prevent cracking of the vertical chords adjacent to the lower spar fitting, which could result in separation of the diagonal brace load path and lead to separation of the strut and engine from the airplane, accomplish the following: \n\nRestatement of Requirements of AD 2000-23-25: Inspections \n\n\t(a) Except as provided by paragraph (b) of this AD, prior to the accumulation of 14,000 total flight cycles, or within 90 days after December 13, 2000 (the effective date of AD 2000-23-25), whichever occurs later: Accomplish paragraphs (a)(1) and (a)(2) of this AD. \n\n\t\t(1) Perform a detailed visual inspection to detect cracking of the vertical chords of the aft torque bulkhead of the outboard nacelle struts, in accordance with Part 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2201, dated September 28, 2000. Thereafter, repeat this inspection at intervals not to exceed 600 flight cycles until paragraph (d) of this AD is accomplished. \n\n\t\t(2) Perform surface eddy current and ultrasonic inspections to detect cracking of the vertical chords of the aft torque bulkhead of the outboard nacelle struts, in accordance with Part 3 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2201, dated September 28, 2000. Thereafter, repeat these inspections at intervals not to exceed 1,200 flight cycles until paragraph (d) of this AD is accomplished. \n\n\tNote 2: For the purposes of this AD, a detailed visual inspection is defined as: "An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required." \n\nOptional Compliance Time \n\n\t(b) If Boeing Service Letter 747-54-055, dated April 24, 1998, was accomplished on the airplane during the modification of the nacelle strut in accordance with AD 95-10-16, amendment 39-9233: Accomplishment of the initial inspection in paragraph (a) of this AD may be deferred until 3,000 flight cycles after accomplishment of the service letter. \n\nRepair \n\n\t(c) If any cracking is detected during any inspection or modification required by this AD: Prior to further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or in accordance with data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved by the Manager, Seattle ACO, asrequired by this paragraph, the approval letter must specifically reference this AD. \n\nNew Requirements of this AD: Modification (Terminating Action) \n\n\t(d) Within 4 years after the effective date of this AD, do the modification of the vertical chords of the aft torque bulkhead of the outboard nacelle struts according to Part 4 of Boeing Alert Service Bulletin 747-54A2201, dated September 28, 2000. After this modification, stop the repetitive inspections required by paragraph (a) of this AD. \n\nAlternative Methods of Compliance \n\n\t(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, 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. \n\n\tNote 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. \n\nSpecial Flight Permits \n\n\t(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 airplane to a location where the requirements of this AD can be accomplished. \n\nIncorporation by Reference \n\n\t(g) Except as provided by paragraph (c) of this AD, the actions shall be done in accordance with Boeing Alert Service Bulletin 747-54A2201, dated September 28, 2000. The incorporation by reference of that document was approved previously by the Director of the Federal Register as of December 13, 2000 (65 FR 70781, November 28, 2000). Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. \n\nEffective Date \n\n\t(h) This amendment becomes effective on July 27, 2001.