What was found
(CAN) ENROUTE, THE CREW OBSERVED A LOW OIL QUANTITY LIGHT ON NR 3 PROPELLER DURING THE DESCENT. THE ACFT WAS RETURNING TO POINT OF DEPARTURE WHEN APPROX 100 MILES FROM DESTINATION THE NR 4 PROPELLER WAS OBSERVED TO EXCEED THE NORMAL OPERATING RPM PERCENT RANGE. THE NR 4 PROPELLER WAS FEATHERED AND THE ENGINE SHUTDOWN. THE ACFT LANDED AT DESTINATION WITHOUT FURTHER PROBLEM. MX TROUBLESHOOTING IN PROGRESS FOR THE NR 3 ENGINE LOW OIL CONDITION AND THE NR 4 ENGINE SHUTDOWN.