What was found
(CAN) THE PILOT FLYING ALONG. WHEN REDUCED POWER FOR DESCENT, OIL PRESSURE DROPPED FROM 90 PSI TO 50 PSI. PILOT LANDED IMMEDIATELY AND SHUT DOWN ENGINE. ENGINE INSP, FOUND NON-MAGNETIC PARTICLES IN OIL FILTER. THE CHIP DETECTOR AND REDUCTION GEARBOX AREA WERE CHECKED. NO PARTICLES FOUND. OIL TANK DRAINED AND CHECKED. NO PARTICLES FOUND. REAR ACCESSORY GEARBOX DRAINED AND CHECKED. FEW SMALL PARTICLES FOUND. PRESSURE RELIEF VALVE REMOVED, DISASSEMBLED. FOUND SMALL PARTICLE OF NON-MAGNETIC MATERIAL ON VALVE SEAT. PRESSURE RELIEF VALVE RE-ASSEMBLED AND INST OIL SYS FLUSHED, REPLENISHED. GROUND RUNS AND INSPS WERE CARRIED OUT IAW WITH P&W MM. NO FURTHER METAL GENERATED.