90-21-21: Pneumatic Duct Brackets

90-21-21 BOEING: Amendment 39-6766. Docket No. 90-NM-108-AD. \n\n\tApplicability: Model 747 series airplanes, equipped with General Electric CF6-45 and CF6-50 engines, as listed in Boeing Service Letter 747-SL-54-32, dated December 4, 1989, certificated in any category. \n\n\tCompliance: Required as indicated, unless previously accomplished.\n \n\tTo eliminate the potential for an engine fire due to a fuel leak, accomplish the following: \n\n\tA.\tWithin the next 60 days or 450 hours time-in-service after the effective date of this AD, whichever occurs first, replace the aluminum pneumatic duct brackets, P/N 69B94023- 1, in the outboard struts, with steel brackets, P/N 69B94023-2, in accordance with Boeing Service Letter 747-SL-54-32, dated December 4, 1989. \n\n\tB.\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 (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\tC.\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 be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, Washington 98055-4056. \n\n\tThis amendment (39-6766, AD 90-21-21) becomes effective on November 16, 1990.