90-20-10 BOEING: Amendment 39-6737. Docket No. 89-NM-75-AD. \n\n\tApplicability: Model 747 series airplanes, listed in Boeing Service Bulletin 747-57- 2187, Revision 2, dated December 15, 1982, certificated in any category. \n\n\tCompliance: Required as indicated, unless previously accomplished. \n\tTo prevent failure of the trailing edge flap track fail-safe straps, accomplish the following: \n\n\tA.\tWithin 4 years from the effective date of this AD, replace old design trailing edge flap track fail-safe straps, if installed, with improved fail-safe straps, and replace bolts having a grip length which is too short with bolts having the correct grip length, as applicable, in accordance with Boeing Service Bulletin 747-57-2187, Revision 2, dated December 15, 1982. \n\n\tB.\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\tC.\tAn alternate means of compliance or adjustmentof the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. \n\n\tNOTE: The request should be submitted directly to the Manager, Seattle ACO, and a copy sent to the cognizant FAA Principal Inspector (PI). The PI will then forward comments or concurrence to the Seattle ACO. \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 be examined at the FAA, Northwest Mountain Region, 1601 Lind Avenue SW, Renton, Washington. \n\n\tThis amendment (39-6737, AD 90-20-10) becomes effective on October 22, 1990.