What was found
(CAN) WHILE ON A SURVEILLANCE MISSION, SURVEILLANCE CREW REPORTED INTERMITTENT OIL SMELL IN THE CABIN WITH CRUISE POWER AT 60% TORQUE. PILOTS WERE NOTIFIED & POWER ADJUSTED TO 65%, AIR QUALITY IMPROVED. NO SMELL WAS EVIDENT IN THE COCKPIT. MISSION WAS COMPLETED AS PLANNED. DURING DESCENT A POWER LEVER SPLIT WITH MATCHED TORQUE WAS NOTICED, WITH THE NR 1 ENG TORQUE HANGING HIGH. ACFT LANDED UNEVENTFULLY. MFG WILL INVESTIGATE TO ESTABLISH ROOT CAUSE & PROVIDE INFORMATION THROUGH SUBSEQUENT SERVICE DIFFICULTY REVIEW MEETING & SUPPORTING DOCUMENTS OR OTHER AGREED UPON COMMUNICATIONS.