AN SF340 CREW SHUT DOWN AN ENG ENRTE DUE TO ENG FIRE WARNING INDICATIONS.

Narrative

WHILE ENRTE TO PIT; ABOUT 80 MI W FROM PIT; THE L 'FIRE DETECTION FAIL' LIGHT ON CENTRAL WARNING PANEL ILLUMINATED. THIS LIGHT ILLUMINATED AND THEN EXTINGUISHED BY ITSELF. IT DID THIS A FEW TIMES AND THEN COMPLETELY STOPPED AS IF THE PROB NEVER EXISTED. BY THIS TIME; THE FO AND I HAD REVIEWED THE APPROPRIATE CHKLIST FOR THIS SIT; EVEN THOUGH THE 'FIRE DETECTION FAIL' LIGHT WAS NOT ILLUMINATED AT THIS POINT IN TIME. ALL INDICATIONS WERE NORMAL. AS WE CONTINUED TO PIT THE L 'FIRE DETECTION FAIL' LIGHT ILLUMINATED AGAIN. HOWEVER; ACCOMPANYING THIS LIGHT WAS THE L 'ENG FIRE' LIGHT ON THE CENTRAL WARNING PANEL. BOTH LIGHTS (THE L 'FIRE DETECTION FAIL' AND THE L 'ENG FIRE' LIGHT) ILLUMINATED AND THEN EXTINGUISHED BY THEMSELVES 2 TIMES AND THEN COMPLETELY STOPPED AS IF THE PROB NEVER EXISTED. AT THIS TIME; WE ASKED OUR FLT ATTENDANT TO CASUALLY WALK THROUGH THE CABIN AND TO PEER THROUGH THE SIDE WINDOWS AND SEE IF SHE COULD SEE ANY SIGNS OF A FIRE WITH THE L ENG. SHE RPTED THAT SHE SAW NO SIGNS OF A L ENG FIRE. WHILE DSNDING INTO PIT; BEING RADAR VECTORS FOR RWY 32; THE L 'ENG FIRE' LIGHT ON THE CENTRAL WARNING PANEL ILLUMINATED; THE L FIRE HANDLE ILLUMINATED; IN ADDITION TO THE SOUNDING OF THE FIREBELL. (WE DID NOT HAVE THE 'FIRE DETECTION FAIL' LIGHT AT ALL THIS TIME; JUST THE L 'ENG FIRE' LIGHT WITH THE ASSOCIATED ALARMS). AT THIS TIME; WE CONTINUED WITH THE APPROPRIATE MEMORY ITEMS FOR AN ENG FIRE; FOLLOWED BY THE APPROPRIATE EMER CHKLISTS; WHILE DECLARING AN 'EMER' WITH ATC. THE 'ENG FIRE' LIGHT WENT OUT IMMEDIATELY AFTER THE ENG FIRE EXTINGUISHING AGENT WAS DISCHARGED. WE CONTINUED TO MANEUVER THE ACFT FOR A SINGLE ENG LNDG AT PIT. UPON COMPLETION OF SUCCESSFUL LNDG; THE ENTIRE FLC; AS WELL AS THE FIRE AND RESCUE CREW VERIFIED THAT THERE WAS NO FIRE AT ALL. THE FIRE AND RESCUE CREW TOLD US THAT THEY PUT THEIR INFRARED LIGHT IN THE ENG AND VERIFIED THAT IT WAS COLD. IN THE INTEREST OF SAFETY; WE DECIDED NOT TO EVAC THE ACFT; AS THE CFR CREW FOLLOWED THE ACFT TO THE GATE. NO HARM WAS DONE TO ANY PERSONS OR PROPERTY. MY CREW; ATC; AND THE CFR CREW PERFORMED GREAT.