What was found
PRIOR TO TAKEOFF THE PILOT NOTICED NR 1 ENGINE FIRE LIGHT AND TONE ACTIVATED. AFTER SHUTDOWN, PASSENGERS WERE EVACUATED AND THE PILOT AND COPILOT VISUALLY CHECKED ENGINE COMPARTMENTS, NO SIGN OF FIRE WAS DETECTED. MAINTENANCE WAS NOTIFIED. TROUBLESHOOTING REVEALED THAT NR 1 ENGINE FIRE DETECTOR AMPLIFIER HAS MALFUNCTIONED. THE MECHANIC REMOVED AND REPLACED NR 1 ENGINE FIRE DETECTOR AMPLIFIER AND AIRCRAFT RETURNED TO SERVICE. (K)