75-23-09 BOEING: Amendment 39-2420. Applies to all Boeing 747-200C and 747-200F series airplanes certificated in all categories. Compliance required as indicated. \n\tIn addition to the door warning light procedures in Boeing B-747 Operations Manual Bulletin 74-13, the following procedures are required to provide assurance of latch system integrity. Before further flight, and thereafter following each nose cargo door operation, accomplish the following: \n\tA.\tClose door electrically or manually until each latch pin is extended and the green, latches closed, light is illuminated on the nose door control panel at the loadmaster's station. \n\tB.\tPull and collar circuit breakers C1407/28V DC "control nose cargo door." Circuit breakers are located on the P15 panel on the right hand side of the electronics bay. Access to this area is either from the ground through the electronics bay hatch or through the main deck floor. Optional to pulling and collaring C1407 and C1572 circuit breakers, pull and collar C1629, C1630, C1631, C1632, C1633, and C1634 circuit breakers on the H122 cargo door power panel. \n\tC.\tPlacard the nose door control panel H121 and the nose wheel well control panel P37, "POWER REMOVED PER AD - CIRCUIT BREAKERS C1407 AND C1572 PULLED:" If optional circuit breakers procedure is used, placard the H122 cargo door power panel, "POWER REMOVED - CIRCUIT BREAKERS PULLED." \n\tD.\tVerify that all 16 latches are closed for dispatch by noting that each latch pin is fully extended into the latch fitting, per Boeing B-747 Dispatch Deviation Procedures Guide, Document D6-33391, page 2.52.6B, View B. \n\tBoeing Service Bulletin 747-52-2117 will be released in the near future which will give instructions for the modification of the nose cargo door latch and lock system. Incorporation of this FAA approved modification will constitute terminating action under the inspection provisions of this AD. \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\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. The documents may also be examined at FAA Northwest Region, 9010 East Marginal Way South, Seattle, Washington. \n\n\tThis amendment becomes effective upon publication in the Federal Register for all persons except those to whom it was made effective immediately by telegram dated October 23, 1975.