What was found
LOUD BANG HEARD IN CRUISE. NR 1 ENGINE STABILIZED IN CRUISE AT 20 PERCENT N1-0 OIL PRESSURE, BUT QUANTITY OK (71-00-1749). NR 1 ENGINE REPLACED, NOW READY FOR POWER 1 LEAK CHECK RUN. EVIDENCE OF DAMAGE TO TOP OF GEAR BOX, INDICATING SUDDEN STOPPAGE. NR 1 ENGINE REMOVED AND REPLACED PER W.C. NR 70T001, AND W/C NR 72T0301 AND J.R.H. OPS CK NORMAL, OK FOR SERVICE. ENG OFF S/N 689919, JT8D-17 ENG ON S/N 709283, JT8D-17A.