What was found
CLE- AFTER STARTING THE APU AT THE GATE THE CREW NOTED A FUEL SMELL IN THE CABIN. CLE- MAINTENANCE INSPECTED THE APU, AND, THE AIRCRAFT WAS RELEASED IAW MEL. BNA- MAINTENANCE REMOVED AND REPLACED THE APU,PERFORMED A OPERATIONAL CHECK, NO DEFECTS NOTED,AND, THE AIRCRAFT WAS APPROVED FOR RETURN TO SERVICE.