What was found
DFW - FLT 1027 - EN ROUTE DFW-SAT, DETECTED VIBRATION AT NR 1 SIDE ENGINE. NR 1 SIDE ENGINE VIBRATION DID NOT SUBSIDE AFTER THROTTLE REDUCTION. AIR INTERRUPTED, RETUREND DFW AND LANDED WITHOUT FURTEHR INCIDENT. REPLACED NR 1 SIDE ENGINE. REPLACED FIRST STAGE FAN BLADE. SYSTEM GROUND CHECKED NORMAL OPERATION. (M)