As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING DESCENT #1 PROP RPM DROPPED TO 820 THEN QUICKLY STABILIZED AT 850. POWERPLANT MSG DISPLAYED. HAPPENED BETWEEN 11,000 - 10,000. REMOVED FROM SERVICE. REMOVED AND REPLACED PCU. OPS TEST GOOD. NO FURTHER DEFECTS. NO POWERPLANT MESSAGES DISPLAYED. NO FAULTS RETURNED. AIRCRAFT RETURNED TO SERVICE.