Narrative:

Right engine 'B' loop came on first. Loop detector switch put in 'a' loop and fire test done. Test complete. Short time later, left engine 'a' loop came on followed by right engine 'a' loop and right engine fire warning followed. Engine instruments were normal. ATC advised and divert to tys requested. About 3-5 mins later, left engine 'B' loop light came on followed by left engine fire warning. Left engine instruments were normal, uneventful landing. Engines were not on fire, warnings were false. Maintenance found 3 of 4 engine anti-ice gaskets were blown, but since engine anti-ice was not in use, decided that was not the cause. No cause could be found. Aircraft was operating with left engine generator MEL (APU supplying electrics). Shutting down good engine due to false fire indications could have led to more severe complications (depressurization, single engine flight, total electrics on APU). Be sure to verify warning with engine instruments. Callback conversation with reporter revealed the following information: the reporter has been flying the DC9 and MD80 for about 15 yrs and has never seen this type incident before or even heard of it. An emergency was declared and the aircraft was on the ground in about 10 mins. The first officer was flying the aircraft and wanted to shut down the first engine immediately, but the reporting captain left it running. The reporter regrets slowing to 250 KTS at 1000 ft when he 'could have kept it rolling' until closer in. The crew stayed with the aircraft until the next morning expecting to fly it out, but the job had not yet been finished. The reporter called his maintenance control the next day to find that the 'B' loop came on at the gate. An electrical short was found in the 'B' loop, but no other problems had been found. Neither cockpit crew person attempted to inspect the engines as there was very little time to do so and the engines are very difficult to see from the cabin on the MD80.

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Original NASA ASRS Text

Title: FALSE WARNING.

Narrative: R ENG 'B' LOOP CAME ON FIRST. LOOP DETECTOR SWITCH PUT IN 'A' LOOP AND FIRE TEST DONE. TEST COMPLETE. SHORT TIME LATER, L ENG 'A' LOOP CAME ON FOLLOWED BY R ENG 'A' LOOP AND R ENG FIRE WARNING FOLLOWED. ENG INSTS WERE NORMAL. ATC ADVISED AND DIVERT TO TYS REQUESTED. ABOUT 3-5 MINS LATER, L ENG 'B' LOOP LIGHT CAME ON FOLLOWED BY L ENG FIRE WARNING. L ENG INSTS WERE NORMAL, UNEVENTFUL LNDG. ENGS WERE NOT ON FIRE, WARNINGS WERE FALSE. MAINT FOUND 3 OF 4 ENG ANTI-ICE GASKETS WERE BLOWN, BUT SINCE ENG ANTI-ICE WAS NOT IN USE, DECIDED THAT WAS NOT THE CAUSE. NO CAUSE COULD BE FOUND. ACFT WAS OPERATING WITH L ENG GENERATOR MEL (APU SUPPLYING ELECTRICS). SHUTTING DOWN GOOD ENG DUE TO FALSE FIRE INDICATIONS COULD HAVE LED TO MORE SEVERE COMPLICATIONS (DEPRESSURIZATION, SINGLE ENG FLT, TOTAL ELECTRICS ON APU). BE SURE TO VERIFY WARNING WITH ENG INSTS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR HAS BEEN FLYING THE DC9 AND MD80 FOR ABOUT 15 YRS AND HAS NEVER SEEN THIS TYPE INCIDENT BEFORE OR EVEN HEARD OF IT. AN EMER WAS DECLARED AND THE ACFT WAS ON THE GND IN ABOUT 10 MINS. THE FO WAS FLYING THE ACFT AND WANTED TO SHUT DOWN THE FIRST ENG IMMEDIATELY, BUT THE RPTING CAPT LEFT IT RUNNING. THE RPTR REGRETS SLOWING TO 250 KTS AT 1000 FT WHEN HE 'COULD HAVE KEPT IT ROLLING' UNTIL CLOSER IN. THE CREW STAYED WITH THE ACFT UNTIL THE NEXT MORNING EXPECTING TO FLY IT OUT, BUT THE JOB HAD NOT YET BEEN FINISHED. THE RPTR CALLED HIS MAINT CTL THE NEXT DAY TO FIND THAT THE 'B' LOOP CAME ON AT THE GATE. AN ELECTRICAL SHORT WAS FOUND IN THE 'B' LOOP, BUT NO OTHER PROBS HAD BEEN FOUND. NEITHER COCKPIT CREW PERSON ATTEMPTED TO INSPECT THE ENGS AS THERE WAS VERY LITTLE TIME TO DO SO AND THE ENGS ARE VERY DIFFICULT TO SEE FROM THE CABIN ON THE MD80.

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.