As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) THERE HAVE BEEN REPEAT EVENTS ON THIS PARTICULAR ACFT. THERE HAVE BEEN REPEATED ADJUSTMENTS TO GET THE PROPELLER RPM TO REMAIN AT 1900 AND MANY TIMES THERE HAVE BEEN REPORTS FROM THE CREWS OF THE PROPELLER RPM INCREASING AND REPORTED SURGES DURING CLIMB AND DURING FLIGHT TRAINING. TROUBLESHOOTING ONGOING.