AD 98-07-15 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, having line numbers 207 through 1088 inclusive, 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 (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 [[Page 16100]] 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 fatigue cracking in the internal skin doublers, which could result in reduced structural integrity of the fuselage and consequent rapid depressurization of the cabin, accomplish the following: (a) For airplanes identified as Groups 1 through 10, inclusive, in Boeing Service Bulletin 747-53A2396, Revision 1, dated February 22, 1996: Prior to the accumulation of 13,000 flight cycles, or within 18 months after the effective date of this AD, whichever occurs later, perform an internal visual inspection to detect cracks of the skin and internal doublers above main entry door 1 at body station (STA) 460, in accordance with Part 2--Inspection of the Accomplishment Instructions of Boeing Service Bulletin 747-53A2396, Revision 1, dated February 22, 1996. For the purposes of this AD, the number of flight cycles in which cabin differential pressure occurs at 2.0 pounds per square inch (psi) or less need not be counted when determining the number of flight cycles that have occurred on the airplane. (1) If no crack is detected during the internal visual inspection required by paragraph (a) of this AD, prior to further flight, perform an open hole high frequency eddy current (HFEC) inspection to detect cracks of the skin and internal doublers above main entry door 1, in accordance with Figure 10 of the service bulletin. (i) If no crack is detected during the open hole HFEC inspection required by paragraph (a)(1) of this AD, prior to further flight, install an external doubler in accordance with Part 4--Modification of the Accomplishment Instructions of the service bulletin. (ii) If any crack is detected during the open hole HFEC inspection, prior to further flight, perform a visual inspection to detect damage of the adjacent structure within 20 inches of the cracks, in accordance with Part 3--Repair of the Accomplishment Instructions of the service bulletin. If any damage is detected, prior to further flight, repair it in accordance with Part 3-- Repair, or the Note specified in paragraph G. of Part 2--Inspection of the Accomplishment Instructions of the service bulletin. (2) If any crack is detected during the internal visual inspection required by paragraph (a) of this AD, prior to further flight, perform a visual inspection to detect damage of the adjacent structure within 20 inches of the cracks, in accordance with Part 3--Repair of the Accomplishment Instructions of the service bulletin. Prior to further flight following accomplishment of this visual inspection, repair any cracked skin or internal doublers, and/or repair adjacent damaged structure, in accordance with Part 3--Repair of the Accomplishment Instructions of the service bulletin. (b) Perform either an internal surface HFEC or external low frequency eddy current (LFEC) inspection to detect damage of the repaired or modified area, in accordance with Part 6--After-Repair or After-Modification Inspection Program of the Accomplishment Instructions of Boeing Service Bulletin 747-53A2396, Revision 1, dated February 22, 1996; at the time specified in paragraph (b)(1) or (b)(2) of this AD, as applicable. (1) For airplanes identified as Groups 1 through 10, inclusive, in Boeing Service Bulletin 747-53A2396, Revision 1, dated February 22, 1996: Inspect within 15,000 flight cycles following accomplishment of either paragraph (a)(1) or (a)(2) of this AD. (2) For airplanes identified as Group 11 in Boeing Service Bulletin 747-53A2396, Revision 1, dated February 22, 1996: Inspect prior to the accumulation of 15,000 total flight cycles. (c) If no damage is detected during any inspection required by paragraph (b) of this AD, repeat the inspections required by paragraph (b) of this AD at the following intervals: (1) If the immediately preceding inspection was conducted using HFEC techniques, conduct the next inspection within 6,000 flight cycles. (2) If the immediately preceding inspection was conducted using LFEC techniques, conduct the next inspection within 3,000 flight cycles. (d) If any damage is detected during any inspection required by paragraph (b) of this AD, prior to further flight, repair it in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. (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. Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. (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. (g) The actions shall be done in accordance with Boeing Service Bulletin 747-53A2396, Revision 1, dated February 22, 1996. 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, ransport 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. (h) This amendment becomes effective on May 7, 1998. Issued in Renton, Washington, on March 25, 1998. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 98-8349 Filed 4-1-98; 8:45 am] BILLING CODE 4910-13-U