What was found
(CAN) TIME THIS INSTALLATION - 1163.3 HOURS. NORMAL START UP AND TAKEOFF UNTIL TRANSLATION WHEN TORQUE AND OIL PRESSURE GAUGES STARTED TO FLUCTUATE. IMMEDIATE LANDING AND SHUT DOWN BY PILOT. ENGINE OIL LEVEL CHECKED, NO OIL FOUND IN ENGINE OIL RESERVOIR. NO EXTERNAL LEAKAGE WAS FOUND. INSPECTION BY AME FOUND GEARBOX TO BE FULL OF OIL AND NOTHING IN ENGINE RESERVOIR. SUBMITTER SUSPECTS SCAVENGE OIL PUMP FAILURE. GEARBOX ASSEMBLY REPLACED AND HELICOPTER RETURNED TO SERVICE.