As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING ANNUAL INSPECTION FOUND COTTER PIN IN THE OIL SUCTION SCREEN. THE COTTER PIN WAS BROKEN INTO THREE PIECES. FURTHER INSPECTION OF THE ENGINE FOUND THE COTTER PIN MISSING FROM CYLINDER NUMBER FOURS LOWER CONNECTING ROD BOLT. I BELIEVE THE COTTER PIN WAS IMPROPERLY INSTALLED DURING A PROPELLER STRIKE INSPECTION WHICH ALLOWED THE COTTER PIN TO MOVE WEARING THE PIN TO THE POINT OF FAILURE.