What was found
(CAN) THIS IS 2ND OCCURANCE OF PROBLEM. PROP INSTALLED ON OTHER ENGINE HAD SAME PROBLEM. BOTH PROPS WERE NEW WITH ASSY DATES OF 11-13-97&12-18-97, SHIPPED 4/16/98. PROP CHECKED AS PRECAUTIONARY MEASURE: NUT IS SOLID STEEL SELF LOCKING NUT, THAT HOLDS PISTON TO PISTON ROD. IF NUT COMES LOOSE, PISTON COMES OFF OF ROD & PROP HAS UNCOMANDED FEATHER WITH NO WAY TO UNFEATHER PROP. PISTON SEALS PITCH CHANGE OIL ON ROD. OTHER PROP SER BP9804B, NUT HAD COME COMPLETELY LOOSE. PROP REMVD&CHECKED. NUT NOT LOOSE ON PISTON ROD, TORQUE OF NUT CHECKED&NO MOVEMENT FOUND.