C402 CARGO FLT HAS 'GLOW' FROM HEATER PORT BUT NO FIRE DETECTED WHEN INSPECTED. THIS MAY HAVE BEEN CAUSED BY FUEL POOLING SINCE THE NOZZLE TO DISPENSE FUEL EVENLY WAS DISLODGED.

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I FEEL THIS PROB WAS PROBABLY CAUSED BY A MALFUNCTIONING HEATER. AT THE TIME OF THE EVENT; I DIDN'T FEEL A PROB EXISTED. HAD I KNOWN THE SIT; I WOULD NOT HAVE CONTINUED FLT. I UNDERSTAND WHAT MIGHT CAUSE THIS SIT IN A MORE KNOWLEDGEABLE WAY NOW. I'VE GAINED EXPERIENCE ON POSSIBLE SYS MALFUNCTION AND BELIEVE A MANUAL WARNING COULD BE ISSUED FOR THE HEATERS ON C402. ON JAN/XA/97 I TAXIED A C402B FROM THE N RAMP OVER TO RWY 25L AT MKE. AFTER RUNUP AND PRETKOF PROCS WERE PERFORMED; I NOTICED A GLOW COMING FROM UNDER THE FRONT R FUSELAGE AREA. SUSPECT OF FIRE; I NOTIFIED GND CTL THAT I WISHED TO SHUT DOWN AND WOULD NEED A DELAY TO INSPECT. ALTHOUGH NO FIRE WAS DETECTED; EMER FIRE CREWS WERE DISPATCHED FOR PRECAUTIONARY MEASURES. I FOUND NO EVIDENCE OF FIRE NOR DID THE EMER CREWS AT THE ARPT. BASED ON THIS EVIDENCE; I RESTARTED AND PROCEEDED WITH THE FLT TO CWA. THIS AND FOLLOWING FLTS WERE UNEVENTFUL. I RETURNED TO MKE 3 DAYS LATER. THAT EVENING I CONTACTED MY COMPANY AND MENTIONED THE INCIDENT ON JAN/XA/97. IT WAS DECIDED THAT FOR PRECAUTIONARY REASONS THAT ACFT SHOULD BE INSPECTED. UPON INSPECTION; IT WAS FOUND THAT THE HEATER COMBUSTION NOZZLE WAS DISPLACED POSSIBLY CAUSING A GLOWING EFFECT FROM THE HEATER EXHAUST PORT. THE PROB WAS REPAIRED ON JAN/XD/97. MAINT ACTION WAS LOGGED BY ME ON JAN/XD/97 INDICATING THE POSSIBLE PROB AND RESULTING REPAIR. THE MECH RETURNED THE ACFT TO SVC ON JAN/XD/97. I HAVE NOT NOTICED ANY PROBS OF THIS NATURE SINCE. BECAUSE OF THE FACT THAT EMER CREWS WERE DISPATCHED; I WANTED TO GIVE A RPT ON THE INCIDENT AND POSSIBLE REASONING BEHIND THE EVENTS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THERE WAS NEVER A DANGER OF FIRE. THE HEATER IS A GAS COMBUSTIBLE HEATER. IT HAS AN EXHAUST PORT AND HOT AIR FROM THE SHROUD GOES INTO THE CABIN. THERE IS A FUEL NOZZLE WHICH DISPENSES FUEL IN A SPRAY. IF THE NOZZLE IS NOT TIGHT THE FUEL POOLS AND WILL NOT BURN EVENLY; CAUSING THE KIND OF GLOW WHICH RPTR SIGHTED. IN THIS INCIDENT THE NOZZLE WAS DISLODGED WHICH CAUSED THE GLOW. SINCE THE TWR CALLED FOR THE FIRE CREWS THEY RPTED THE INCIDENT TO THE FAA. FAA WRONGLY FEELS RPTR GOT OUT OF THE ACFT TO PUT OUT A FIRE. HOWEVER; THERE WAS NO FIRE. FAA FEELS THERE WERE VIOLATIONS AND WANTS TO SUSPEND RPTR'S LICENSE FOR A PERIOD OF TIME.