HEAVY FREIGHT ACFT WAS AWAITING TKOF CLRNC AND ANOTHER ACFT REPORTED AN ENG FIRE ON THE FREIGHTER. AFTER THE ENG FIRE PROCEDURE WAS ACCOMPLISHED; FIRE WAS STILL REPORTED; SO THE FLT CREW EVACUATED THE ACFT.

Narrative

THIS EVENT INVOLVED AN ENG FIRE DURING TAXI OUT. 4 ENG START WAS NORMAL. TAXI OUT OF RAMP WAS NORMAL. A DISTR ON TAXI TO RWY XXL WAS A RADAR MALFUNCTION. THE CAPT USED RAMP TO GET OUT OF THE TFC FLOW AND DIAGNOSE THE PROB. ENGS #1 AND #4 WERE SHUT DOWN FOR FUEL CONSIDERATIONS. THE RADAR BECAME OPERATIVE AND THE CAPT RE-ENTERED THE TAXI STREAM. THE BEFORE TKOF CHKLIST WAS INITIATED FROM THE TOP; AGAIN. ENG STARTS ON ENGS #1 AND #4 WERE NORMAL. AS WE SAT AT THE #1 POS FOR TKOF; ANOTHER ACFT RPTED AN ENG FIRE ON AN ACFT AT RWY XXL. THE CAPT QUERIED THE XMISSION TO DETERMINE IF OUR ACFT WAS THE ONE BEING REFERRED TO. IT WAS; AND THE OTHER ACFT SUGGESTED THAT THE 'TORCH' WAS ABOUT 3-4 FT LONG AND ON THE R INBOARD ENG. DURING THIS TIME OUR CREW AND THE MAINT SUPVRS ON BOARD COULD SEE NO UNUSUAL INDICATIONS OF ENG MALFUNCTION OR FIRE. AFTER ENG #3 WAS SHUT DOWN AND FIRE AGENT DISCHARGED; THE OTHER ACFT CREW CONFIRMED THAT THE 'TORCH' STILL EXISTED. THE CAPT DECIDED THAT AN EMER EVAC WAS APPROPRIATE AND WAS ACCOMPLISHED. ALL EQUIP WORKED NORMALLY; THE EVAC WAS SMOOTH AND THERE WERE NO INJURIES. WE ACCOUNTED FOR EVERYONE (7 SOULS) AND GATHERED IN FRONT OF THE ACFT UNTIL EMER SVCS ARRIVED. EVEN THOUGH I HAD REVIEWED OPS LIMITS AND EMER PROCS ON THE COMMUTE TO WORK; I SHOULD HAVE TESTED FOR FIRE DETECTION SYS FAILURE DURING THE INCIDENT. ALSO; I FOUND MYSELF UNCOMFORTABLE WHEN FIRING THE FIRE AGENT AND I SHOULD HAVE BEEN BETTER AT CHALLENGE; RESPONSE; RESPONSE ALTHOUGH IT MAY NOT HAVE BEEN THAT IMPORTANT ON THE GND. THE CREW PERFORMED WELL TOGETHER; THE CAPT MADE GOOD WELL CONSIDERED DECISIONS AND THE MAINT SUPVRS WERE HELPFUL AND FOLLOWED DIRECTIONS WELL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THIS WAS A NIGHT FLT WITH RAIN FALLING AT THE ARPT. THE REPORTER INDICATED THAT THEY HAD MADE THE TURN TO HOLD SHORT OF THE RWY; AND THE REPORTING ACFT WAS STILL ON THE PARALLEL TXWY. AS A RESULT; THE REPORTING ACFT WAS LOOKING DOWN THE WING AND ACTUALLY REPORTED A FIRE FOR THE WRONG ENG. THE #4 ENG WAS ACTUALLY PRODUCING THE FLAME. A DEFECTIVE FUEL/OIL HEAT EXCHANGER WAS DISCOVERED. THIS RESULTED IN A MIXTURE OF FUEL AND OIL BEING DISTRIBUTED TO THE ENG BEARINGS.