As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE PROP CONTROL WAS RETURNED FOR INABILITY TO COMMAND THE PROPELLER TO FEATHER. UPON DISASSEMBLY, A SMALL ROUND METAL PLATE WAS FOUND TO BE PARTIALLY BLOCKING AN OIL TRANSFER TUBE. THE ROUND PLATE WAS SUBSEQUENTLY DETERMINED TO BE PART OF THE INLET TRANSFER FILTER. LIGHT SURFACE DAMAGE WAS NOTED ON THE OIL TRANSFER TUBE AND PCU HOUSING.