What was found
AT TAKEOFF THRUST SETTING (ANV) LOUD EXPLOSION HEARD IN COCKPIT AND NR 1 ENGINE LOW OIL PRESSURE LIGHT ILLUMINATED AND OIL QTY DECREASED TO 2 GAL THEN INCREASED TO 3 GAL AFTER SHUTDOWN. ABORTED TAKEOFF AND PERFORMED EMERGENCY ENGINE SHUTDOWN PROCEDURES PER AOM 2-1-2. RETURNED TO RAMP. OIL PRESSURE ALSO DECREASED TO 20 PSI AND CONTINUED TO DECREASE. DISCOVERED T3 AND T4 HAD SEPARATED FROM ENGINE CAUSING DAMAGE TO TAIL PIPE ASSEMBLY. REMOVED AND REPLACED NR 1 ENGINE. OPS CHECK OK. LEAK CHECKED OK IAW B727 MM 71-00. (M)