What was found
ON 2/6/04 A NORMAL ENGINE RUN AND TAXI WAS BEING PERFORMED. AS WE ATTEMPTED TO TAXI OUT THE LT SIDE SEEMED TO HAVE NO THRUST OR MOVEMENT. WE HEARD A LOUD THUMP OR POP ON THE LT SIDE OF THE AIRCRAFT. AT THAT TIME WE ABORTED THE TAXI AND SHUT DOWN BOTH ENGINES IN ORDER TO INVESTIGATE THE PROBLEM. THE LEFT ENGINE PROP WAS FOUND IN THE FULL REVERSE POSITION AFTER ENGINE STOPPED ROTATING. INVESTIGATION AND PROP REMOVAL REVEALED A PLUG RETAINING RING WAS NOT IN PROPER POSITION AND THE PLUG HAD BEEN DISLODGED BY THE FEATHER SPRING. THE PROP WAS SENT TO A PROPELLER REPAIR STATION AND THE RETAINING RING WAS BELIEVED TO BE THE INCORRECT PN. (WP01200406679)