What was found
(CAN) DURING FLIGHT THE #4 ENGINE OIL CONSUMPTION WAS OBSERVED. ENGINE WAS OPERATED AT REDUCED THRUST UNTIL OIL PRESSURE INDICATION WAS OBSERVED AND OIL QUANTITY AT 0.7 GALLONS.PRECAUTIONARY SHUTDOWN WAS CARRIED OUT. POST FLIGHT I NSPECTION FOUND A FLANGE CRACKED AT THE OIL RETURN LINE TO THE ANGLE GEARBOX. THE FLANGE AND "O" RING WERE REPLACED AND THE AIRCRAFT RETURNED TO SERVICE.