Narrative:

Aircraft was dispatched with left engine fire detection loop B inoperative. Loop 'a' had given intermittent warnings on jan/sat/01. This had been cleared on jan/mon/01 without definitive maintenance action -- something to the effect of loop 'a' inspected test, no faults found, ok for service. En route to fll, loop 'a' began to intermittently activate causing an intermittent fire left engine warning. (Aircraft was being operated loop 'a' only per MEL.) following checklist, I retarded throttle of left engine. Prior to securing the left engine, having knowledge of loop 'a' history of alarming, I elected to select loop 'B' not alarm. I then tested loop 'B' and obtained satisfactory test. Loop 'B' had been placarded inoperative for nuisance warnings, not for lack of fire detection capability. During all this, we were in moderate turbulence. The turbulence then lessened in intensity and loop 'a' ceased to alarm. Loop 'a' had not ceased alarming with throttle being retarded, but did cease with sensation of turbulence. Taking all this into consideration, I chose to continue to fll. The first officer did not concur and recommended en route diversion. No further fire warnings occurred for the duration of the flight. I believe I had unequivocal evidence of lack of an engine fire. I also had fire detection capability for the remainder of the flight. I do, however, at this point question whether my actions were in compliance with company procedures. Supplemental information from acn 500260: aircraft was dispatched with a placarded left engine B loop inoperative. Logbook review revealed a history of left engine a loop intermittent in-flight, signed off on jan/sat/01. Per MEL, the aircraft was flown with left engine a loop selected. The left engine fire light came on when we encountered intermittent moderate chop at FL260 just north of sby. We executed the fire in-flight checklist. Based on the aircraft's loop a history, we proceeded with the fire checklist (determine bad loop light) to gather additional information. Test revealed a loop abnormal with B loop testing normal. Per the checklist, the captain chose to fly in left engine B loop. I discussed with the captain that because we had the B loop placarded, that technically we could not confirm fire detection capability on the left engine and therefore we should divert. Because we did not have any secondaries, B loop tested normal, a loop was a repeat logbook entry, we both agreed that we most likely had a false indication, not a fire. I recommended iad, phl, or lga as suitable diverts vice land at nearest suitable airport. The captain elected to continue to fll. The aircraft landed at fll without further incident.

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Original NASA ASRS Text

Title: MD80 CREW HAD FIRE WARNING ON #1 ENG.

Narrative: ACFT WAS DISPATCHED WITH L ENG FIRE DETECTION LOOP B INOP. LOOP 'A' HAD GIVEN INTERMITTENT WARNINGS ON JAN/SAT/01. THIS HAD BEEN CLRED ON JAN/MON/01 WITHOUT DEFINITIVE MAINT ACTION -- SOMETHING TO THE EFFECT OF LOOP 'A' INSPECTED TEST, NO FAULTS FOUND, OK FOR SVC. ENRTE TO FLL, LOOP 'A' BEGAN TO INTERMITTENTLY ACTIVATE CAUSING AN INTERMITTENT FIRE L ENG WARNING. (ACFT WAS BEING OPERATED LOOP 'A' ONLY PER MEL.) FOLLOWING CHKLIST, I RETARDED THROTTLE OF L ENG. PRIOR TO SECURING THE L ENG, HAVING KNOWLEDGE OF LOOP 'A' HISTORY OF ALARMING, I ELECTED TO SELECT LOOP 'B' NOT ALARM. I THEN TESTED LOOP 'B' AND OBTAINED SATISFACTORY TEST. LOOP 'B' HAD BEEN PLACARDED INOP FOR NUISANCE WARNINGS, NOT FOR LACK OF FIRE DETECTION CAPABILITY. DURING ALL THIS, WE WERE IN MODERATE TURB. THE TURB THEN LESSENED IN INTENSITY AND LOOP 'A' CEASED TO ALARM. LOOP 'A' HAD NOT CEASED ALARMING WITH THROTTLE BEING RETARDED, BUT DID CEASE WITH SENSATION OF TURB. TAKING ALL THIS INTO CONSIDERATION, I CHOSE TO CONTINUE TO FLL. THE FO DID NOT CONCUR AND RECOMMENDED ENRTE DIVERSION. NO FURTHER FIRE WARNINGS OCCURRED FOR THE DURATION OF THE FLT. I BELIEVE I HAD UNEQUIVOCAL EVIDENCE OF LACK OF AN ENG FIRE. I ALSO HAD FIRE DETECTION CAPABILITY FOR THE REMAINDER OF THE FLT. I DO, HOWEVER, AT THIS POINT QUESTION WHETHER MY ACTIONS WERE IN COMPLIANCE WITH COMPANY PROCS. SUPPLEMENTAL INFO FROM ACN 500260: ACFT WAS DISPATCHED WITH A PLACARDED L ENG B LOOP INOP. LOGBOOK REVIEW REVEALED A HISTORY OF L ENG A LOOP INTERMITTENT INFLT, SIGNED OFF ON JAN/SAT/01. PER MEL, THE ACFT WAS FLOWN WITH L ENG A LOOP SELECTED. THE L ENG FIRE LIGHT CAME ON WHEN WE ENCOUNTERED INTERMITTENT MODERATE CHOP AT FL260 JUST N OF SBY. WE EXECUTED THE FIRE INFLT CHKLIST. BASED ON THE ACFT'S LOOP A HISTORY, WE PROCEEDED WITH THE FIRE CHKLIST (DETERMINE BAD LOOP LIGHT) TO GATHER ADDITIONAL INFO. TEST REVEALED A LOOP ABNORMAL WITH B LOOP TESTING NORMAL. PER THE CHKLIST, THE CAPT CHOSE TO FLY IN L ENG B LOOP. I DISCUSSED WITH THE CAPT THAT BECAUSE WE HAD THE B LOOP PLACARDED, THAT TECHNICALLY WE COULD NOT CONFIRM FIRE DETECTION CAPABILITY ON THE L ENG AND THEREFORE WE SHOULD DIVERT. BECAUSE WE DID NOT HAVE ANY SECONDARIES, B LOOP TESTED NORMAL, A LOOP WAS A REPEAT LOGBOOK ENTRY, WE BOTH AGREED THAT WE MOST LIKELY HAD A FALSE INDICATION, NOT A FIRE. I RECOMMENDED IAD, PHL, OR LGA AS SUITABLE DIVERTS VICE LAND AT NEAREST SUITABLE ARPT. THE CAPT ELECTED TO CONTINUE TO FLL. THE ACFT LANDED AT FLL WITHOUT FURTHER INCIDENT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.