As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW REPORTED RECEIVING A APU FIRE LOOP FAIL AND A FALSE FIRE INDICATION. MAINTENANCE INSPECTED AND REPLACED THE FIRE DETECTION CONTROL UNIT IN ACCORDANCE WITH DORNIER MAINTENANCE MANUAL 26-00-00. OPERATIONAL CHECKS WERE PERFORMED AND THE AIRCRAFT WAS RELEASED FOR SERVICE.