DURING R ENG START ON AN ATR 72; WITH THE PROP BRAKE ACTIVATED; THE PROP BEGAN SPINNING; CAUSING A FRONT CASE FIRE. CAUSED BY MECHANICAL FAILURE OF PROP BRAKE.

Narrative

CREW STARTED THE #2 ENG WITH PROP BRAKE ON. AFTER GPU WAS REMOVED WAS WHEN WE FIRST NOTICED THE PROP TURNING WITH THE PROP BLADE ENGAGED. CAPT AND FO BECAME AWARE OF SMELL BUT NO SMOKE WAS OBSERVED OR NOTED IN CABIN. CAPT IMMEDIATELY DEPRESSED THE DC AUX PUSH-BUTTON TO RELEASE THE PROP BRAKE. SMELL BECAME WORSE WHEN PROP BRAKE WAS RELEASED AND ZZZ RAMP ALERTED CREW TO FIRE ON #2 ENG. CREW IMMEDIATELY SHUT DOWN #2 ENG; GAVE THE VICTOR CALL AND RAN ENG FIRE ON THE GND CHKLIST AS WELL AS THE EMER EVAC CHKLIST. ALL PAX WERE DEPLANED AND 1 MAN COMPLAINED HE HURT HIS FINGER. ZZZ CFR CAME TO LOOK AT FINGER AND ACFT ENG. FO STAYED WITH ACFT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE PROP STARTED TO SPIN WITH THE PROP LOCK ACTIVATED BUT THE MECHANICAL FUNCTION OF THE BRAKE FAILED AND SEIZED CAUSING A FIRE IN THE BRAKE ASSEMBLY AND FORWARD PART OF THE ENG. THE CREW WAS ALERTED BY A RAMP PERSON WHO OBSERVED FLAMES COMING OUT OF THE FRONT PART OF THE ENG AND OVER THE COWLING. THIS AREA OF THE ENG IS NOT COVERED BY THE FIRE WARNING LOOP AND THE CREW WAS UNAWARE OF THE FIRE. THE FIRE BOTTLES WERE ACTIVATED BUT WERE INEFFECTIVE AS THE FIRE WAS TOO FAR FORWARD. THE RPTR STATED THE ACFT WAS EVACED WITH ONLY 1 MINOR INJURY. THE RPTR SAID THE PROP WAS WELDED TO THE ENG CASE AND WOULD NOT TURN AND THE COWLING AND NACELLE WERE DAMAGED EXTENSIVELY. THIS IS THE FIRST PROP BRAKE INCIDENT THIS CREW HAD EXPERIENCED.