FAILED FIRE WARNING LOOPS PRECEDE ENGINE FIRE INDICATION ON MD80. FLT RETURNS TO DEP ARPT.

Narrative

EVERYTHING WAS NORMAL AS WE CLBED OUT TO 10000 FT. ATC ISSUED CLB TO 17000 FT. UPON INITIATION OF CLB AT APPROX 10500 FT MASTER CAUTION LIGHT ILLUMINATED; NOTICED THAT THAT LOOP LIGHT WAS ON. FO; WHO WAS FLYING AT THE TIME; LOOKED UP AND NOTICED BOTH LOOP LIGHTS ON FOR L ENG. SHORTLY THEREAFTER WE GOT A FIRE INDICATION IN L ENG. I TOLD THE FO TO LEVEL OFF. SILENCED THE BELL AND STARTED FIRE/SEPARATION/SEVERE DAMAGE CHKLIST. AS ACFT LEVELED OFF FIRE LIGHT WENT OUT ALONG WITH LOOP LIGHTS. I COMPLETED THE CHKLIST DOWN TO THE POINT OF; 'AT CAPT'S DISCRETION USE ENG AT IDLE' AS THE LIGHT HAD NOW GONE OUT. NOTIFIED ATC OF THE PROB AND ASKED TO RETURN TO ZZZ. TOLD THEM THAT WE HAD A FIRE INDICATION IN L ENG. FO WAS NOW USING THE RADIOS AS I HAD TO FINISH CHKLISTS; NOTIFY FLT ATTENDANTS AND TALK TO PEOPLE. USUAL STUFF FROM ATC; SOULS ONBOARD; FUEL; ARE WE DECLARING AN EMER; ETC. WHEN ASKED; I INFORMED FO TO ASK FOR THE ARF TO ROLL. FLT ATTENDANTS WERE NOTIFIED. THEY WERE ALREADY AWARE OF THE SITUATION AS THE #1 HAD HEARD THE BELL GO OFF. AS WE WERE ON THE DOWNWIND TO BASE LEG FLT ATTENDANT FROM REAR OF ACFT CHIMED SAYING THERE WAS A FUEL SMELL FROM THE L ENG. IT WAS AT THIS POINT I DECIDED TO SHUT DOWN L ENG AS I DID NOT WANT TO PUMP FUEL ONTO A POSSIBLE ENG FIRE. COMPLETED PRECAUTIONARY ENG SHUTDOWN CHKLIST; REVIEWED SINGLE ENG LNDG PROC. AS I WAS EXTREMELY BUSY DOING CHKLISTS ON BASE TO FINAL I DID NOT HAVE TIME TO CHK ENG PARAMETERS ON THE WIND-MILLING ENG. WE WERE DEFINITELY NO MORE THAN 5 MINS ON 1 ENG. PROBABLY CLOSER TO 3 MINS. ARF FOLLOWED US OFF THE RWY. STOPPED ON HIGH SPD EXIT; THEY CHKED FOR FIRE; NONE NOTED. FIRE CHIEF GAVE US THE ALL CLR SO I TAXIED BACK TO A GATE AS THEY FOLLOWED FOR SAFETY. UPON ARR AT GATE PAX WERE DEPLANED.