What was found
FLT 81 - KOA-HNL - SERVICE VIBRATION ON NR 1 ENGINE AFTER TAKEOFF AND SUDDEN LOSS OF THRUST, EPR DECREASED FROM 1.98-1.5 EGT AT 550 ONE MINUTE THEN CLIMBED TO RED LINE. NR 1 THRUST REVERSER FOD DAMAGE. NR 1 TAILPIPE EXTENSION FOD DAMAGE. RETURNED AIRCRAFT TO KOA. REPLACED NR 1 ENGINE ASSY IAW FORMS 17211, 17212, 17213, 17214, M-215. RUN-UP CHECK OK. REPLACED NR 1 THRUST REVERSER ASSY IAW FORM M-211. OPS AND LEAK CHECK OK. REPLACED NR 1 TAILPIPE EXTENSION IAW FORM M-211. RII COMPLETED FOR INSTALLATION OF NR 1 ENGINE PER FORM M-211, M-212, M-213, M-214, AND M-215. (M)