As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LT TORQUE AND LT PROP FLUCTUATING BY 5 PERCENT AND 20 RPM WHILE INFLIGHT. AIR RETURN TO MEM. REMOVED AND REPLACED LT PCU IAW SF340 AMM CHAPTER 61-20-05-04 AND 71-00-00. ALL CHECKS GOOD AT THIS TIME, P/N ON/OFF 8210-153, S/N ON 11916865, S/N OFF 12096466.