What was found
(CAN) TURBOMACHINE SENT FOR INVEST AFTER ENGINE EXPERIENCED A DROP IN "ALL PARAMETERS" AND SHUT ITSELF DOWN. A FIREBALL WAS SEEN COMING FROM REAR OF ENGINE AND UPON LDG, OIL WAS NOTICED BLOWN OUT OF INTAKE. DISASSY OF ENGINE FOUND COMPONENTS RETAINED BY NR 4 BEARING RETAINING NUT WERE SEVERELY FRETTED AND NR 4 BEARING RETAINING NUT WAS NO LONGER TIGHT. SUBMITTER SUGGESTED NR 4 BEARING FAILED DUE TO BACKING OFF OF NR 4 BEARING RETAINING NUT. HOWEVER, LOSS OF A NR 3 AND NR 4 BEARING AREA MULTIPLE JET OIL NOZZLE PLUG SUGGESTED FAILURE MAY HAVE BEEN DUE TO OIL STARVATION. LOSS OF NR 3 AND NR 4 BEARING AREA MULTIPLE JET OIL NOZZLES FLOODED ENG WITH OIL CAUSING A FIREBALL IN HOT SECTION. PART TC: 20,653.