What was found
PILOT WAS PERFORMING A NIGHT CURRENCY FLIGHT, AS HE BEGAN HIS FINAL APPROACH THE LT ENG FIRE WARNING CAME ON. THE PILOT PULLED BACK POWER & THE FIRE LIGHT WENT OUT BELOW 40% TORQUE. PUSHING THE POWER UP CAUSED THE LIGHT TO COME BACK ON. THE PILOT LANDED WITHOUT INCIDENT. INSPECTED THE ACFT, NO HEAT DAMAGE, OR FIRE COULD BE FOUND & THE SYS GND TESTED NORMAL. THE ACFT WAS GND RUN & THE PROBLEM COULD NOT BE DUPLICATED. FOUND ONE BLEED AIR DUCT COUPLING & CONNECTOR SEEMED LOOSE GOING FROM THE ENG COMPARTMENT INTO THE AIRFRAME. THE SYS WAS PRESS CHECKED & FOUND EXCESSIVE LEAKAGE. THIS BLEED AIR LEAKAGE WAS INLINE WITH THE FIRE DETECTION WIRE LOOP. THE COUPLING SEALS WERE REMOVED & FOUND TO BE WORN & HARD. THE SEALS IN THE COUPLER & CONNECTOR WERE REPLACED & THE ACFT WAS GND RUN & TESTED NORMAL.