As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE APU FIRE LIGHT AND BELL ACTIVATED AS APU WAS BEING STARTED ON LANDING. THE APU FIRE CHECKLIST WAS COMPLETED, THE APU FIRE BOTTLE WAS DISCHARGED AND THE APU WAS SHUT DOWN. MAINTENANCE FOUND THE APU HAD TORCHED. THE APU COMBUSTOR UNIT WAS REMOVED AND REPLACED. OPERATION OF THE APU CHECKED GOOD. THE APU FIRE BOTTLE WAS REPLACED.