What was found
(CAN) THE APU FAILED AS THE ACFT WAS PARKED ON THE GATE. SMOKE WAS SEEN COMING FROM THE APU. THE SMOKE QUICKLY DISSIPATED. EMS WAS CALLED AS A PRECAUTION. THERE WAS NOT ADVERSE REACTION AS PASSENGERS DEPLANED. APU INSPECTION FOUND GUIDE VANES MISSING AND MELTED METAL IN APU TAIL PIPE. IAW AMM 49-00-00, APU INTAKE PLENUM CHECKED NO FAULTS & CLEANED. IAW T/C 2-492000-04AC01. APU REPLACED IAW T/C A32X-49-11-11-000-001-0100 & T/C A32X-49-11-11-400-001-0100. APU CHECKED SERVICEABLE.