What was found
(CAN) WHILE PERFORMING ENGINE GROUND RUNS AT 80 PERCENT NG, OIL WAS OBSERVED LEAKING FROM THE NR 2 ENGINE. AT THE SAME TIME, SMOKE AND FUMES ENTERED THE CABIN THROUGH THE ENVIRONMENTAL DUCTS. ENGINES WERE SHUTDOWN AND THE ACFT RETURNED TO THE HANGAR. UPON INVESTIGATION, MAINTENANCE DISCOVERED OIL LEAKING FROM THE TRANSFER TUBE WHERE IT MATES WITH THE EXTERNAL COUPLING. PACKING WAS REPLACED. TRANSFER TUBE REINSTALLED AND CHECKED SERVICEABLE. NO OBVIOUS DAMAGE TO THE REMOVED PACKING.