What was found
(CAN) JUST BEFORE TURNING BASE LEG FOR LANDING THE RT BMEP GAUGE FELL TO ZERO. NO OIL WAS OBSERVED LEAKING FROM ENGINE ALTHOUGH THE OIL QUANTITY WAS SLOWLY FALLING. LANDING WAS CARRIED OUT NORMALLY. ON ROLL OUT QUANTITY WAS READING 8 GALLONS, SO THE RT ENGINE WAS SHUT DOWN. MAINTENANCE DISCOVERED THAT THE SCAVENGE PUMP HAD INGESTED A PIECE OF A CASTLE NUT WHICH HAD BROKEN OFF ONE OF THE NUTS P/N 542 FROM ONE OF THE REDUCTION PINION GEAR SHAFTS. THIS HAD CAUSED THE FAILURE OF THE GEAR/SHAFT P/N 100243 IN THE ACCESSORY DRIVE CASE.