SF34 CREW HAD FALSE ENG FIRE WARNING IN DAY; CLASS E; AIRSPACE.

Narrative

ON INITIAL CLBOUT AFTER THE CLB CHKLIST HAD BEEN RUN; THE ENG FIRE DETECTION FAIL CAUTION ILLUMINATED FOR A FRACTION OF A SECOND ALONG WITH THE MASTER CAUTION ATTN GETTER. IT SELF CLRED WITH NO ACTION FROM THE CREW. THIS SCENARIO OCCURRED AGAIN TWICE IN RAPID SUCCESSION. THE APPROPRIATE ABNORMAL CHKLIST WAS RUN. IT STATES TO 'CLOSELY MONITOR ENG INSTS AND CONTINUE THE FLT.' THE CAUTION ILLUMINATED A 4TH TIME AND REMAINED ON FOR 10-15 SECONDS. THE CREW DISCUSSED THIS SIT AND DETERMINED THAT THE DETECTION SYS HAD FAILED AND THAT THERE WAS A SHORT. WHILE TALKING TO COMPANY AT DAYTON; THE MASTER WARNING; FIRE BELL; AND ENG FIRE LIGHT ILLUMINATED FOR LESS THAN 1 SECOND AND CLRED ITSELF. I LOOKED OUT THE L WINDOW AND DID NOT NOTICE BLISTERING PAINT; SMOKE OR FLAMES; ALL ENG INDICATIONS WERE NORMAL. ALL INDICATIONS OF A FIRE PER SAAB EMER CHKLIST WERE ABSENT. WITHIN A FEW SECONDS THE MASTER CAUTION AND WARNING ATTN GETTERS BOTH ILLUMINATED ALONG WITH ENG FIRE DETECTION FAIL AND ENG FIRE; ALONG WITH FIRE BELL. AS I STATED; WE HAVE 2 ALARMS. THEY BOTH SELF CLRED. WE DETERMINED THIS MUST BE AN INDICATION PROB DUE TO THE UNRELIABLE FIRE DETECTION SYS -- THE FIRST ABNORMALITY. WE WERE WITHIN 5 MINS OF DAYTON AND ADVISED ATC WE WERE RETURNING DUE TO AN ENG FIRE DETECTION SYS FAILURE. THERE WERE NO ALARMS; LIGHTS; OR BELLS GOING OFF IN THE COCKPIT. WE DID NOT HAVE ANY ENG FIRE INDICATION SO WE DID NOT RUN A MEMORY ITEM FOR A CONDITION WE DID NOT HAVE. TO SHUT DOWN THE ENG COULD NOT BE JUSTIFIED BASED ON OUR SOP'S; TRAINING; AND SYS KNOWLEDGE. THAT WOULD HAVE BEEN AN OVERREACTION BY THE FLC. ONCE WE INITIATED THE 180 DEG TURN; NO FURTHER WARNINGS OCCURRED. MAINT DISCOVERED THE FIRE LOOP WAS TOO CLOSE TO THE NACELLE AND WAS SHORTING OUT. IT WAS REPOSITIONED AND THE FLT CONTINUED WITHOUT INCIDENT. DURING TRAINING; CREWS SHOULD BE GIVEN MORE ADVICE ON HOW TO HANDLE FALSE WARNINGS.