As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
A NUMBER TWO ATTITUDE/HEADING FAIL WARNING MESSAGE ILLUMINATED, DURING THE CLIMB-OUT PHASE OF THE FLIGHT. THE AIRCRAFT RETURNED TO THE FIELD AND LANDED, WITHOUT ANY FURTHER PROBLEMS. MAINTENANCE INSPECTED AND REPLACED THE NUMBER TWO ATTITUDE AND HEADING REFERENCE UNIT (AHRU), IN ACCORDANCE WITH DORNIER MAINTENANCE MANUAL 34-21-20. OPERATIONAL CHECKS WERE COMPLETED, AND THE AIRCRAFT WAS RETURNED TO SERVICE.