What was found
DURING CLIMB OUT, THE LT ENGINE FIRE WARNING LIGHT CAME ON. THE PILOT DECLARED AND EMERGENCY, RETURNED TO BASE, LANDED WITHOUT INCIDENT. THE PILOT DID NOT SEE FLAMES OR SMOKE COMING FROM THE ENGINE AND DID NOT HAVE ANY OTHER INDICATIONS OF AN ENGINE FIRE, THEREFORE HE DID NOT SHUT THE ENGINE DOWN INFLIGHT. MAINTENANCE INSPECTED THE ENGINE FOR SIGNS OF FIRE AND NONE WERE FOUND. TROUBLESHOOTING OF THE LT FIRE DETECTION SYSTEM REVELED A BAD FIRE DETECTOR AT THE 12 O`CLOCK POSITION ON THE LT ENGINE. WHEN THE WIRES WERE MOVED GOING INTO THE DETECTOR THE WARNING LIGHT WOULD ILLUMINATE. MAINTENANCE REPLACE THE FIRE DETECTOR, OPERATION CHECKED, OK, AND THE AC WAS RETURNED TO SERVICE. (K)