What was found
THE NR 1 ENGINE FIRE WARNING LIGHT AND BELL ACTIVATED DURING CLIMB OUT OF EWR. BOTH FIRE BOTTLES WERE DISCHARGED, THE NR 1 ENGINE WAS SHUTDOWN, AND AIRCRAFT WAS RETURNED TO EWR WHERE IT LANDED WITHOUT INCIDENT. MAINTENANCE FOUND THE NR 1 ENGINE BOTTOM FIRE DETECTOR LOOP AT FAULT. THE FIRE DETECTOR LOOP AND THREE CONNECTORS WERE REMOVED AND REPLACED. BOTH FIRE BOTTLES WERE REMOVED AND REPLACED. THE NR 1 ENGINE WAS RUN AT TAKEOFF POWER AND ALL INDICATIONS WERE NORMAL.