What was found
(CAN) DURING CLIMB THE #2 ENGINE TORQUE STARTED TO CYCLE UP AND DOWN 10-24 PERCENT - FUEL FLOW AND NL ALSO CYCLED UP AND DOWN. PILOTS SELECTED E.C.U. TO MANUAL, TURNED OFF PROP SYNC. AND BLEED AIR BUT FLUCTUATIONS STILL OCCURRED. AIRCRAFT RETURNED TO POINT OF DEPARTURE. MAIN FUEL CONTROL WAS REPLACED AND THE ENGINE GROUND RUN SERVICEABLE. AIRCRAFT RETURNED TO SERVICE.