What was found
ON DEPARTURE, FIRE DETECTOR LEFT ENGINE FAIL ILLUMINATED AT 12,000 FEET, WENT OUT AT ABOUT 13,000 FEET FOLLOWED BY A LEFT ENGINE FIRE INDICATION. INDICATION WENT OUT WHEN THROTTLE WAS MOVED TO IDLE. OVERWEIGHT LANDING APPROX 106,500 LBS. FOUND BORESCOPE PLUG 'F' ON NR 1 ENGINE LOOSE. RESECURED PLUG PER MM 72-33. PERFORMED FIM 26-11, TASK 807. NO DEFECTS NOTED. A/C LANDED BELOW OVERWEIGHT LANDING LIMIT OF 110,000 LBS. A/C OK FOR SERVICE REF MM 05-51-04, 1B.