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.