77-12-04 MCDONNELL DOUGLAS: Amendment 39-2921. Applies to Model DC-10-10F and DC-10-30F airplanes certificated in all categories. \n\n\tCompliance required within the next 1000 hours time in service after the effective date of this AD, unless already accomplished. \n\n\tTo reduce the possibility that operational errors could result in dispatch of an aircraft with the upper cargo door unlatched or unlocked, accomplish (a) and either (b) or (c) as follows: \n\n\t(a)\tInstall a lock mechanism viewing window on the upper cargo door and add a new instruction placard per McDonnell Douglas DC-10 Service Bulletin No. 52-120, dated September 4, 1974, or later FAA approved revision. \n\n\t(b)\tInstall an upper cargo door vent door with integral blockers for the torque tube and lock tube and add instruction placard per McDonnell Douglas DC-10 Service Bulletin No. 52-137, dated July 9, 1976, or later FAA approved revision, or \n\n\t(c)\tAfter each operation of the upper cargo door, prior to flight verify that the door is flush with the fuselage, that lock pin engagement has occurred by observing through the viewing port, and secure the upper cargo door by accomplishing (1) and either (2) or (3) as follows: \n\n\t\t(1)\tInstall bolt (NAS 6304-17 or NAS 6404U17) with locknut in lieu of pip pin in lock tube hole. \n\n\t\t(2)\tOpen and secure with positive lock-out devices, the upper cargo door power circuit breakers (B1-1341, B1-1342, and B1-1343) located on the flight engineer's lower main circuit breaker panel and "upper cargo door power control" circuit breaker (B1-1340) located on the forward left cabin equipment panel; or \n\n\t\t(3)\tRemove or hydraulically disconnect lock tube actuator (P/N 477667-5503). \n\n\t(d)\tEquivalent modifications may be used when approved by the Chief, Aircraft Engineering Division, FAA Western Region. \n\n\t(e)\tSpecial flight permits may be issued in accordance with FAR's 21.197 and 21.199 to operate airplanes to base for the accomplishment of the modificationsrequired by this AD. \n\n\tThis amendment becomes effective July 22, 1977.