What was found
ENG FIRE WARNING LIGHT ILLUMINATED IN FLT. PILOT PERFORMED REQUIRED EMER PROCEDURES AND PERFORMED EMER LANDING. WHEN MAINT ARRIVED, FIRE WARNING LIGHT HAD EXTINGUISHED. FIRE WARNING SYSTEM WAS INSPECTED AND NO DEFECTS FOUND. MECH CLEANED ALL FIRE DETECTORS REMOVING EXTERIOR CONTAMINATIONS. AC WAS GROUND RUN WITHOUT FIRE LIGHTS ILLUMINATING AND AC WAS RETURNED TO SERVICE. 3 MINUTES INTO RETURN FLIGHT, ENG FIRE LIGHT ILLUMINATED A SECOND TIME. AGAIN FIRE WARNING LIGHT WAS EXTINGUISHED WHEN MAINT ARRIVED. AGAIN A DETAILED INSPECTION WAS PERFORMED AND NO DEFECTS FOUND. MAINT AGAIN CLEANED ALL DETECTORS AND RETURNED THE AIRCRAFT TO SERVICE. NO ADDITIONAL FIRE WARNING HAS OCCURRED ON PROCEEDING FLIGHTS.