90-20-02 BOEING: Amendment 39-6739. Docket No. 90-NM-48-AD. \n\n\tApplicability: Model 727 series airplanes, listed in Boeing Service Bulletin 727-57-0107, Revision 6, dated November 22, 1989, certificated in any category. \n\n\tCompliance: Required as indicated, unless previously accomplished. \n\n\tTo detect cracks in the wing center section front spar web, accomplish the following: \n\n\tA.\tExcept as provided in paragraphs F. and G. of this AD, prior to the accumulation of 15,000 landings since manufacture, or prior to the accumulation of 500 additional landings after September 11, 1986 (the effective date of AD 86-18-03, Amendment 39-5384), whichever occurs later, visually inspect the wing center section for cracks in accordance with Figure 1 of Boeing Service Bulletin 727-57-107, Revision 6, dated November 22, 1989 (hereafter referred to as "the service bulletin"). If no cracks are detected, repeat the visual inspection at intervals not to exceed 1,000 landings. \n\n\tB.\tIf a single crack less than two inches in length is detected on either side of body buttock line (BBL) 0.0, before further flight, the crack must be stop-drilled at each end in accordance with the Boeing 727 Structural Repair Manual (SRM), and visually reinspected at intervals not to exceed 10 landings for crack growth beyond the stop holes. If crack growth occurs beyond any stop hole, accomplish the procedures required by paragraph C. or D. of this AD. \n\n\tC.\tIf a single crack between two and five inches in length is detected on either side of BBL 0.0, before further flight, the crack must be stop-drilled at each end in accordance with the Boeing 727 SRM, and the crack must be repaired in accordance with Boeing Drawing Number 69-62491-2. Visually reinspect the affected area at intervals not to exceed 200 landings for crack growth beyond any stop hole. If crack growth occurs beyond any stop hole, accomplish the procedures required by paragraph D. of this AD. \n\n\tD.\tIf any crack greater than five inches is detected, or if more than one crack on either side of BBL 0.0 is detected, they must be stop-drilled in accordance with the Boeing 727 SRM, and modified in accordance with paragraph E. of this AD. \n\n\tE.\tTo terminate the repetitive inspection requirements of paragraphs A., B., C., F., and G. of this AD, accomplish one of the following: \n\n\t\t1.\tAccomplish the modification described in Part I.D. of the Accomplishment Instructions of the service bulletin; or \n\n\t\t2.\tAccomplish the interim modification described in Part I.E. of the Accomplishment Instructions of the service bulletin. Prior to the accumulation of 12,000 landings after the incorporation of the interim modification, eddy current inspect the fastener and any stop holes for crack growth, oversize the holes, stop-drill any new cracks in accordance with the Boeing 727 SRM, and incorporate the terminating modification in accordance with Part I.E. of the Accomplishment Instructions of the service bulletin.F.\tAirplanes that have been modified prior to accumulating 20,000 landings, by installing angles back-to-back with existing stiffeners, must be inspected prior to the accumulation of 12,000 landings since the modification or within the next 1,000 landings after the effective date of this Amendment, whichever occurs later, in accordance with Figure 1 of the service bulletin. If cracks are found, before further flight, accomplish paragraph B., C., or D. of this AD, as appropriate. If no cracks are found, reinspect thereafter at intervals not to exceed 1,000 landings. \n\n\tG.\tAirplanes that have been modified after accumulating more than 19,999 landings, by installing angles back-to-back with existing stiffeners must be inspected within the next 1,000 landings after September 11, 1986 (the effective date of Amendment 39-5384), in accordance with Figure 1 of the service bulletin. If cracks are found, before further flight, accomplish paragraph B., C., or D. of this AD, as appropriate.If no cracks are found, reinspect thereafter at intervals not to exceed 1,000 landings. \n\n\tH.\tAn alternate means of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Seattle Aircraft Certification Office, FAA, Transport Airplane Directorate. \n\n\tNOTE: The request should be submitted directly to the Manager, Seattle Aircraft Certification Office, and a copy sent to the cognizant FAA Principal Inspector (PI). The PI will then forward comments of concurrence to the ACO. \n\n\tI.\tSpecial flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD. \n\n\tAll persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124. These documents may beexamined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 1601 Lind Avenue S.W., Renton, Washington. \n\n\tThis amendment supersedes Amendment 39-5384, AD 86-18-03.\n \tThis amendment (39-6739, AD 90-20-02) becomes effective October 22, 1990.