Narrative:

I was the PF on flight as we took off from rst runway 13 en route to msp. The WX at the time was low IMC with light snow. Shortly after calling for 'flaps up, climb normal' the #4 engine fire light and fire bell came on. I called for engine fire memory items. The captain confirmed the indication and commenced the memory items. As soon as the #4 throttle was moved aft, the fire indications went out. All engine readings were normal and a visual inspection of the engine showed no smoke or fire present. Subsequently, the captain and I discussed leaving the engine at idle to keep the #4 generator on line due to the impending instrument approach in low IMC. During this time, ATC personnel in the rst tower handed the flight off to departure. The captain checked in with departure, informed them of our situation and requested they stand by. I asked the captain to review the qrc memory card. I opted to stay at 210 KTS because we were still heading away from the rochester airport. I then asked for #2 autoplt on, and we completed the after takeoff checklist. I asked for pom engine fire checklist. About this time, ATC instructed us to climb to a higher altitude. We were in VMC at this point and I asked the captain to keep us at this altitude and to get a turn back to rst for the ILS to runway 13. I did not want to continue to climb up and head away from rst. ATC gave us a turn back to the northwest and I believe, but cannot say for certain, we remained at our current altitude. The captain then gave a quick brief to the flight attendants and requested and received the WX at rst and msp. The WX was better at msp so the captain elected to return to msp based on better WX and a longer runway. I felt comfortable with the captain's decision. En route to msp, the captain updated ATC, the flight attendants, informed the company and made a PA to the passenger informing them of our situation and intentions. Once we were headed back to msp we increased to 250 KIAS and received priority handling for an ILS to runway 12R. I executed a flight director hand flown 3 engine ILS to an uneventful landing. We taxied to the gate and shut down the aircraft using normal procedures. Supplemental information from acn 639591: all engine parameters were stable and within the normal (far below maximum ranges), visual inspection from the cockpit did not indicate a problem, and no other indications made me suspect a continuing malfunction. As a result, I decided to keep the engine at idle and monitor it instead of shutting it down. Meanwhile I advised ATC the situation was under control. ATC declared the emergency. After landing, we advised ATC no further crash fire rescue equipment would be required. The mechanic determined, while I was there, that no temperature parameters were exceeded.

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Original NASA ASRS Text

Title: AFTER RECEIVING A FIRE WARNING ON #4 ENG, A BA46 FLT CREW DETERMINES THAT THEY WILL CONTINUE TO DEST ARPT BECAUSE OF DETERIORATING WX AT DEP ARPT, RST.

Narrative: I WAS THE PF ON FLT AS WE TOOK OFF FROM RST RWY 13 ENRTE TO MSP. THE WX AT THE TIME WAS LOW IMC WITH LIGHT SNOW. SHORTLY AFTER CALLING FOR 'FLAPS UP, CLB NORMAL' THE #4 ENG FIRE LIGHT AND FIRE BELL CAME ON. I CALLED FOR ENG FIRE MEMORY ITEMS. THE CAPT CONFIRMED THE INDICATION AND COMMENCED THE MEMORY ITEMS. AS SOON AS THE #4 THROTTLE WAS MOVED AFT, THE FIRE INDICATIONS WENT OUT. ALL ENG READINGS WERE NORMAL AND A VISUAL INSPECTION OF THE ENG SHOWED NO SMOKE OR FIRE PRESENT. SUBSEQUENTLY, THE CAPT AND I DISCUSSED LEAVING THE ENG AT IDLE TO KEEP THE #4 GENERATOR ON LINE DUE TO THE IMPENDING INST APCH IN LOW IMC. DURING THIS TIME, ATC PERSONNEL IN THE RST TWR HANDED THE FLT OFF TO DEP. THE CAPT CHKED IN WITH DEP, INFORMED THEM OF OUR SIT AND REQUESTED THEY STAND BY. I ASKED THE CAPT TO REVIEW THE QRC MEMORY CARD. I OPTED TO STAY AT 210 KTS BECAUSE WE WERE STILL HEADING AWAY FROM THE ROCHESTER ARPT. I THEN ASKED FOR #2 AUTOPLT ON, AND WE COMPLETED THE AFTER TKOF CHKLIST. I ASKED FOR POM ENG FIRE CHKLIST. ABOUT THIS TIME, ATC INSTRUCTED US TO CLB TO A HIGHER ALT. WE WERE IN VMC AT THIS POINT AND I ASKED THE CAPT TO KEEP US AT THIS ALT AND TO GET A TURN BACK TO RST FOR THE ILS TO RWY 13. I DID NOT WANT TO CONTINUE TO CLB UP AND HEAD AWAY FROM RST. ATC GAVE US A TURN BACK TO THE NW AND I BELIEVE, BUT CANNOT SAY FOR CERTAIN, WE REMAINED AT OUR CURRENT ALT. THE CAPT THEN GAVE A QUICK BRIEF TO THE FLT ATTENDANTS AND REQUESTED AND RECEIVED THE WX AT RST AND MSP. THE WX WAS BETTER AT MSP SO THE CAPT ELECTED TO RETURN TO MSP BASED ON BETTER WX AND A LONGER RWY. I FELT COMFORTABLE WITH THE CAPT'S DECISION. ENRTE TO MSP, THE CAPT UPDATED ATC, THE FLT ATTENDANTS, INFORMED THE COMPANY AND MADE A PA TO THE PAX INFORMING THEM OF OUR SIT AND INTENTIONS. ONCE WE WERE HEADED BACK TO MSP WE INCREASED TO 250 KIAS AND RECEIVED PRIORITY HANDLING FOR AN ILS TO RWY 12R. I EXECUTED A FLT DIRECTOR HAND FLOWN 3 ENG ILS TO AN UNEVENTFUL LNDG. WE TAXIED TO THE GATE AND SHUT DOWN THE ACFT USING NORMAL PROCS. SUPPLEMENTAL INFO FROM ACN 639591: ALL ENG PARAMETERS WERE STABLE AND WITHIN THE NORMAL (FAR BELOW MAX RANGES), VISUAL INSPECTION FROM THE COCKPIT DID NOT INDICATE A PROB, AND NO OTHER INDICATIONS MADE ME SUSPECT A CONTINUING MALFUNCTION. AS A RESULT, I DECIDED TO KEEP THE ENG AT IDLE AND MONITOR IT INSTEAD OF SHUTTING IT DOWN. MEANWHILE I ADVISED ATC THE SIT WAS UNDER CTL. ATC DECLARED THE EMER. AFTER LNDG, WE ADVISED ATC NO FURTHER CFR WOULD BE REQUIRED. THE MECH DETERMINED, WHILE I WAS THERE, THAT NO TEMP PARAMETERS WERE EXCEEDED.

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.