What was found
(CAN) PILOT HAD TO CARRY OUT A PRECAUTIONARY IN-FLIGHT SHUTDOWN OF NR 1 ENGINE DUE TO TORQUE FLUCTUATION AND OIL PRESSURE DROPPING. ACFT LANDED SAFELY WITHOUT FURTHER INCIDENT. NR 1 ENGINE TORQUE LIMITER HAD COME AWAY FROM THE REDUCTION GEAR BOX THREADED BOSS, WHILE THE TORQUE LIMITER ADAPTER, THREADING WAS FOUND STRIPPED & WORN. DUE TO THE TORQUE LIMITER COMING AWAY FROM THE REDUCTION GEAR BOX, THIS ALLOWED PRESSURIZED OIL TO LEAK PAST, WHICH WOULD ACCOUNT FOR THE TORQUE FLUCTUATIONS AND DROPPING OIL PRESSURE.