AD 2000-12-19 Airworthiness Directives; Boeing Model 747 Series Airplanes

Models named: 747 series. Read the applicability below — it usually turns on serial or part numbers too.

Model 747 series airplanes, as listed in Boeing Alert Service Bulletin 747-53A2425, dated October 29, 1998; certificated in any category. Note 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 (g) 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 detect and correct cracking in the aft pressure bulkhead, which could result in rapid decompression of the fuselage or overpressurization of the tail section, accomplish the following: Initial and Repetitive Inspections (a) Except as provided by paragraph (f) of this AD, prior to the accumulation of 20,000 total flight cycles, or within 12 months after the effective date of this AD, whichever occurs later, perform a detailed visual inspection of the upper half of the aft pressure bulkhead to detect cracking, in accordance with Figure 6 or 7, as applicable, of Boeing Alert Service Bulletin 747-53A2425, dated October 29, 1998. Repeat the detailed visual inspection thereafter at intervals not to exceed 1,500 flight cycles. For areas of the upper half of the aft pressure bulkhead that have been repaired previously, this detailed visual inspection may be deferred for up to 15,000 flight cycles after accomplishment of the repair, as described in the NOTE in paragraph 3.D. of the Accomplishment Instructions of the alert service bulletin. Note 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.” (b) Except as provided by paragraph (f) of this AD, if no cracking is detected during the initial detailed visual inspection required by paragraph (a) of this AD: Within 1,500 flight cycles after accomplishment of that inspection, perform a high frequency eddy current (HFEC) inspection of the upper and lower halves of the aft pressure bulkhead to detect cracking, in accordance with Figure 8 of Boeing Alert Service Bulletin 747-53A2425, dated October 29, 1998. Repeat the HFEC inspection thereafter at intervals not to exceed 3,000 flight cycles. (c) Except as provided by paragraph (f) of this AD, if any cracking is detected during any inspection required by paragraph (a) of this AD: Prior to further flight, perform an HFEC inspection of the upper and lower halves of the aft pressure bulkhead to detect cracking, in accordance with Figure 8 or 9, as applicable, of Boeing Alert Service Bulletin 747-53A2425, dated October 29, 1998. Repeat the HFEC inspection thereafter at intervals not to exceed 3,000 flight cycles. Repair (d) Except as provided by paragraphs (e) and (f) of this AD, if any cracking is detected during any inspection required by paragraph (a), (b), or (c) of this AD: Prior to further flight, repair in accordance with Boeing Alert Service Bulletin 747-53A2425, dated October 29, 1998. (e) If any cracking is detected during any inspection required by paragraph (a), (b), or (c) of this AD, and Boeing Alert Service Bulletin 747-53A2425, dated October 29, 1998, specifies to contact Boeing for repair instructions: Repair any cracking, prior to further flight, in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate; or in accordance with data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative (DER) 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, as required by this paragraph, the approval letter must specifically reference this AD. Operator's “Equivalent Procedure” (f) Where Boeing Alert Service Bulletin 747-53A2425, dated October 29, 1998, specifies that an inspection or a repair, as applicable, may be accomplished in accordance with an operator's “equivalent procedure”: The inspection or repair, as applicable, must be accomplished in accordance with the applicable chapter of the Boeing 747 Maintenance Manual or the Boeing 747 Structural Repair Manual specified in the alert service bulletin. Alternative Methods of Compliance (g) 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 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. Special Flight Permits (h) 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. Incorporation by Reference (i) Except as provided by paragraphs (e) and (f) of this AD, the actions shall be done in accordance with Boeing Alert Service Bulletin 747-53A2425, dated October 29, 1998. 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 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. (j) This amendment becomes effective on July 28, 2000. Issued in Renton, Washington, on June 12, 2000. Donald L. Riggin, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 00-15308 Filed 6-22-00; 8:45 am] BILLING CODE 4910-13-P