What was found
IAH - FLIGHT 3020, THE CREW REPORTED A BURNING SMELL AFTER THE APU START. THE APU THEN FAILED AND WOULD NOT RESTART. THE AIRCRAFT RETURNED TO THE GATE WHERE MAINTENANCE PLACED THE APU ON MEL 49-00-00 CAT - C CTL NUMBER 157685, AND THE AIRCRAFT WAS APPROVED FOR RETURN TO SERVICE. THE AIRCRAFT RETURNED TO IAH ON 11/04/08 WHERE MAINTENANCE REMOVED AND REPLACED THE APU STARTER GENERATOR, OPERATIONALLY CHECKED WITH NO DEFECTS, REMOVED THE MEL, AND THE AIRCRAFT WAS APPROVED FOR RETURN TO SERVICE.