49-30-01 DOUGLAS AND CONVAIR: Applies to All DC-6 and 240 Aircraft Equipped With Curtiss Model C632S-A Propellers. \n\n\tCompliance required as soon as possible but not later than August 15, 1949. \n\n\tBecause of a number of cracks having been discovered in the threaded portion of the hub barrels of the C632S-A propellers, preflight visual inspections must be made in accordance with Curtiss Instructions to all owners dated May 12, 1949. \n\n\tIt is strongly recommended that wherever the necessary equipment is available, magnetic inspections be made in accordance with Curtiss Instructions entitled, "Field Magnetic Inspection of C632S-A Hubs". \n\n\tAny hubs revealing cracks must be retired from service immediately. \n\n\tThe above inspections are to remain in effect as long as these propellers are in service regardless of any rework accomplished. \n\n\tOperational procedures for the Douglas DC-6 during ground run, takeoff and climb, as recommended by the Douglas Co. telegram of May 25, 1949, must also be complied with.