91-12-17 McDONNELL DOUGLAS: Amendment 39-7029. Docket No. 90-NM-280-AD. \n\n\tApplicability: All McDonnell Douglas Model DC-9-15F, -32F, -33F, -34F, and C-9 (military) series airplanes, certificated in any category. \n\n\tCompliance: Required as indicated, unless previously accomplished. \n\n\tTo prevent inadvertent opening of the forward upper cargo door in flight, a condition which could result in loss of pressurization and reduced controllability of the aircraft, accomplish the following: \n\n\tA.\tWithin four months after the effective date of this AD, and thereafter at intervals not to exceed one year, perform magnetic particle inspections on the cargo door latch spool fitting attach bolts or replace the non-Inconel cargo door latch spool fitting attach bolts with new bolts, in accordance with the Accomplishment Instructions for Phase 2 of McDonnell Douglas DC-9 Alert Service Bulletin A52-174, dated August 7, 1990, or Revision 1, dated December 14, 1990. \n\n\t\t1.\tIf a bolt doesnot pass the magnetic particle inspection, prior to further flight, replace it with a new bolt and seal in accordance with the service bulletin. \n\n\t\t2.\tIf a bolt passes the magnetic particle inspection, prior to further flight, reinstall the bolt and seal in accordance with the service bulletin. \n\n\tB.\tThe inspections required by paragraph A. of this AD are not required for Inconel bolts, part numbers RA21026-7-28, 77711-7-28, and 3D0031-7-28. \n\n\tC.\tWithin two years after the effective date of this AD, replace all non-Inconel cargo door latch spool fitting attach bolts with Inconel bolts, part numbers RA21026-7-28, 77711-7-28, or 3D0031-7-28, in accordance with the Accomplishment Instructions of Phase 3 of McDonnell Douglas DC-9 Alert Service Bulletin A52-174, dated August 7, 1990; or Phase 4 of McDonnell Douglas DC-9 Alert Service Bulletin A52-174, Revision 1, dated December 14, 1990. Installation of Inconel bolts constitutes terminating action for the requirements of paragraph A. of this AD. \n\n\tD.\tSpecial flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes unpressurized to a base for the accomplishment of the requirements of this AD. \n\n\tE.\tAn alternative method of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Los Angeles Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. \n\n\tNOTE: The request should be forwarded through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Los Angeles 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 McDonnell Douglas Corporation, P.O. Box 1771, Long Beach, California 90846-0001, Attention: Business Unit Manager, Technical Publications, C1-HCW (54-60). These documents may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 1601 Lind Avenue S.W., Renton, Washington; or the Los Angeles Aircraft Certification Office, 3229 East Spring Street, Long Beach, California. \n\n\tThis amendment (39-7029, AD 91-12-17) becomes effective on July 15, 1991.