89-23-07: Steel Bolt Inspection

89-23-07 BOEING: Amendment 39-6376. Docket No. 89-NM-63-AD. \n\n\tApplicability: Model 747 series airplanes, listed in Boeing Service Bulletin 747-51- 2043, dated June 30, 1988, certificated in any category. \n\n\tCompliance: Required as indicated, unless previously accomplished. \n\n\tTo prevent structural damage caused by cracked or fractured H-11 steel bolts, accomplish the following: \n\n\tA.\tPrior to the accumulation of 4 years total time-in-service, or within the next 15 months after the effective date of this AD, whichever occurs later, visually inspect H-11 steel bolts for cracks or fractures, in accordance with Boeing Service Bulletin 747-51-2043, dated June 30, 1988, at the following locations: \n\n\t\t1.\tBody landing gear inboard and outboard trunnion vertical support. \n\n\t\t2.\tWing landing gear beam upper chord to longeron attachment. \n\n\t\t3.\tWing landing gear beam lower chord to crease beam attachment. \n\n\t\t4.\tBody station (BS) 2598 horizontal stabilizer hinge attachment. \n\n\t\t5.\tBS 2598 longeron splice fitting attachment at stringers 11 and 23. \n\n\t\t6.\tFin to body attachment. \n\n\t\t7.\tThe horizontal stabilizer front spar jack screw attachment. \n\n\tB.\tIf a cracked or fractured bolt is found, replace with an Inconel 718 bolt, prior to further flight, in accordance with Boeing Service Bulletin 747-51-2043, dated June 30, 1988. \n\n\tC.\tIf a cracked or fractured bolt is found and if Inconel 718 bolts are unavailable, replace the cracked or fractured bolt with an H-11 steel bolt, prior to further flight, in accordance with Boeing Service Bulletin 747-51-2043, dated June 30, 1988. Repeat the visual inspection required by paragraph A., above, at intervals not to exceed 18 months. \n\n\tD.\tIf no cracking or fracture is found, repeat the visual inspection required by paragraph A., above, at intervals not to exceed 18 months. \n\n\tE.\tWithin the next 48 months after the effective date of this AD, replace all affected H-11 steel bolts with Inconel 718 bolts,in accordance with Boeing Service Bulletin 747-51-2043, dated June 30, 1988. \n\n\tF.\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, Northwest Mountain Region. \n\n\tNOTE: The request should be forwarded through an FAA Principal Maintenance Inspector (PMI), who may add any comments and then send it to the Manager, Seattle Aircraft Certification Office. \n\n\tG.\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 Airplanes, P.O. Box 3707, Seattle, Washington 98124. The documents may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 17900 Pacific Highway South, Seattle, Washington, or Seattle Aircraft Certification Office, 9010 East Marginal Way South, Seattle, Washington. \n\n\tThis amendment (39-6376, AD 89-23-07) becomes effective on December 4, 1989.