As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE ON APPROACH, THE LEFT HAND ENGINE TORQUE SURGED FROM 90 TO 10 PERCENT AND WAS UNCONTROLLABLE. THE CREW FOLLOWED THE QUICK REFERENCE HANDBOOK AND SHUT THE ENGINE DOWN. FLIGHT 2558 THEN LANDED AT PIT. MAINTENANCE INSPECTED AND REPLACED THE ENGINE CONTROL UNIT IN ACCORDANCE WITH DORNIER MAINTENANCE MANUAL 71-00-00. OPERATIONAL CHECKS WERE PERFORMED AND THE AIRCRAFT WAS RELEASED FOR SERVICE.