What was found
SCHEDULED INSPECTION AND MAINTENANCE, WHILE PERFORMING A COMPRESSION CHECK, IT WAS NOTED THAT THE ENGINE TURNING TOOL WENT INTO THE LOWER PULLEY DRIVE SPLINE FARTHER THAN NORMAL. FURTHER INVESTIGATION REVEALED THE ENGINE DRIVE SHAFT TO BE IMPROPERLY POSITIONED IN THE LOWER PULLEY. THE BELT DRIVE ASSEMBLY WAS REMOVED FROM THE HELICOPTER. EXAMINATION OF THE ENGINE-MOUNTED DRIVE ADAPTER REVEALED THE PN 77416 FORWARD LOWER COUPLING BUMPER PLUG WAS MISSING. THIS PLUG DETERMINES THE POSITION OF THE DRIVE SHAFT IN BOTH THE ENGINE AND THE LOWER PULLEY OF THE BELT DRIVE.