As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PROPS SET AT 1050 FOR BRAKING AND POWER LEVELS REDUCED TO FLIGHT IDLE NR 1 ENGINE TORQ STARTED TO SURGE +/- 5 PERCENT FROM 10 PERCENT TORQUE, AND PROP RPM INCREASED. TROUBLESHOOTING NOTED NR 1 ENGINE FAILED OPERATION TEST OF BETA LOCKOUT SYSTEM DUE TO POWER LEVER SWITCH 6141S3 ACTUATING ABOVE FLIGHT IDLE. ADJUSTED 6141S3. NO PARTS REPLACED. OPERATIONAL CHECK GOOD. AIRCRAFT RETURNED TO SERVICE.