What was found
FIRE BELL RANG WITH NO OTHER INDICATIONS. THROUGH ISOLATION SWITCH MOVEMENT, CONDITION WAS DETERMINED TO BE ON LEFT ENGINE. ENGINE AND FIRE DETECTION SYSTEM EXAMINED. NO DEFECTS NOTED. LT ENG FIRE SYS LIGHTS AND BELL CAME ON. ENGINE SECURED AND NR 1 FIRE BOTTLE FIRED. LIGHTS AND BELL EVENTUALLY WENT OUT. FOUND SMALL AMT OF SEMI-CONDUCTIVE BLK GREASE IN CONNECTOR PLUG IN LT ENG PLYON. CLEANED PLUG, SYS NOW NORMAL. PROBLEM OCCURRED APPROX 45 HRS AFTER ENG CHANGE AND THIS PLUG WAS DISCONNECTED AT THAT TIME.