FLC OF LGT ACR ACFT RESPONDED TO AN ENG FIRE WARNING BY REDUCING ENG PWR TO IDLE AND CONTINUING ON TO DEST SINCE THEY HAD JUST PREVIOUSLY RETURNED AFTER TKOF FOR THE SAME REASON AND FOUND NO EVIDENCE OF A FIRE.

Narrative

THIS FLT WAS OUR SECOND DEP OUT OF CUN THAT DAY; THE FIRST HAVING RETURNED TO CUN WITH THE #2 ENG SHUT DOWN DUE TO AN INTERMITTENT FIRE WARNING ON THAT ENG. (NO EVIDENCE OF FIRE WAS NOTED ON ANY ENG INST OR ON VISUAL INSPECTION INSIDE THE COWLING ON THE GND.) THIS FLT WE GOT THE EXACT SAME INTERMITTENT FIRE LIGHT AND BELL ON CLBOUT; AND AS BEFORE ALL ENG INSTS WERE NORMAL. BUT THIS TIME WE NOTICED THE #2 FIRE CIRCUIT GND DETECTOR LIGHT FLICKER IN ASSOCIATION WITH THE BELL AND LIGHT. KNOWING WE HAD 2 SEPARATE FIRE DETECTION LOOPS WITH CORRESPONDING CIRCUIT BREAKERS WE WERE ABLE TO ISOLATE THE LOOP THAT SEEMED TO BE GNDING OUT AND CAUSING THE INTERMITTENT INDICATION. KNOWING WE HAD AT LEAST 1 GOOD FIRE DETECTION LOOP; AND GIVEN OUR PREVIOUS EXPERIENCE; WE MADE THE DECISION TO OPERATE THE #2 ENG AT IDLE; AS OPPOSED TO SHUTTING IT DOWN. SINCE OUR PROCS DO NOT INCLUDE AN INTERMITTENT FIRE WARNING WE WERE DEVIATING FROM OUR SOP BY NOT SHUTTING DOWN THE ENG. IN OUR ESTIMATION WE ACTED IN THE SAFEST MANNER BASED ON ALL INFO AVAILABLE.