What was found
(CAN) THE NR 1 ENGINE OIL SEAL FAILED ALLOWING THE ENGINE OIL TO ENTER THE AIRFLOW INTO THE COMPRESSOR AND THEN GET BURNED UP IN THE HOT SECTION. THIS LOSS OF OIL WAS FINALY MADE KNOWN TO THE PILOT WHEN THE OIL PRESSURE WARNING LIGHT ILLUMINATED WITH THE CORRESPONDING DROP OF PRESSURE ON THE ENGINE OIL PRESSURE GUAGE. THE PILOT WAS ON FINAL TO A LANDING AND COMPLETED THE LANDING AND ENGINE SHUTDOWN WITH NO IRREGULARITIES. THE TIME LINE IS UNKNOWN AS TO HOW LONG IT TOOK TO EMPTY THE OIL TANK AS IT WAS AT THE PROPER LEVEL AT THE PREFLIGHT INSPECTION AND THE FAILURE HAPPENED APPROXIMATELY 4 FLIGHT HOURS LATER.