What was found
AFTER LANDING, THE FLIGHT CREW NOTED THAT THE NR 3 ENGINE OIL WARNING LIGHT ILLUMINATED. OIL PRESSURE INDICATED 25 PSI. UPON POST FLIGHT INSPECTION, CREW NOTICED OIL LEAKING FROM THE NR 3 ENGINE COWLING AND OIL FILTER BYPASS BUTTON WAS POPPED. AIRFRAME TT 9153.0 HOURS. NR 3 ENGINE TT 8958.2 HOURS NR3 ENGINE CYCLES 6436. AIRCRAFT WAS INSPECTED BY MAINTENANCE AND SUSPECTED AN INTERNAL FAILURE. LOANER ENGINE WAS INSTALLED IN THE NR 3 POSITION. ORIGINAL NR 3 ENGINE WAS SENT TO MFG FOR TEARDOWN INSPECTION.