81-15-06 BOEING: Amendment 39-4165. Applies to all Model 747 series airplanes, certificated in all categories, listed in Boeing Alert Service Bulletin No. 747-52A2180 Revision 1, or later FAA approved revision. \n\n\tCompliance is required as indicated unless already accomplished.\n \n\tTo prevent jamming of the crew compartment overhead hatch, accomplish the following: \n\n\tA.\tWithin 90 days of the effective date of this AD, magnetic particle inspect Rack Pin Assemblies P/N's H759-47, -49, -51, -93 used on the crew compartment overhead hatch assemblies in accordance with Boeing Alert Service Bulletin No. 747-52A2180, Revision 1, or later FAA approved revisions.\n \n\tB.\tUnless previously inspected, any Rack pin assemblies, P/N's H759-47, -49, -51, -93, installed after the effective date of this AD must be magnetic particle inspected prior to installation in accordance with Boeing Alert Service Bulletin No. 747-52A2180, Revision 1, or later FAA approved revisions. \n\n\tC.\tRack pin assemblies found to be crack free may be suitably identified as directed by Boeing Alert Service Bulletin No. 747-52A2180 Revision 1, or later FAA approved revisions and returned to service. \n\n\tD.\tRack pin assemblies found to be cracked are to be discarded. \n\n\tE.\tAlternate means of compliance or other actions which provide an equivalent level of safety may be used when approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region.\n \n\tF.\tAircraft may be ferried to a maintenance base for repair in accordance with FAR 21.197 and FAR 21.199. \n\tThe manufacturer's specifications and procedures identified and described in this directive are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1).\n \n\tAll persons affected by this directive who have not already received these documents from the manufacturer, may obtain copies upon request to Boeing Commercial Airplane Company, P.O. Box 3707, Seattle, Washington 98124. These documents may also beexamined at FAA Northwest Region, 9010 East Marginal Way South, Seattle, Washington 98108. \n\n\tThis amendment becomes effective July 28, 1981.