As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED ENGINE VIBRATING BADLY AND LOSING POWER ON CLIMB-OUT. AIRCRAFT MADE A SAFE LANDING AT DEPARTURE AIRPORT. OIL WAS ALL ALONG THE RIGHT SIDE OF THE AIRCRAFT. ON REMOVING THE COWL, A HOLE APPROXIMATELY 2 INCHES BY 3 INCHES WAS IN THE CASE AND A CONNECTION ROD CAP WHICH APPEARED TO BE NR 3 WAS STICKING OUT OF THE HOLE WHICH WAS AT THE DATA PLATE ATTACH POINT. THE ENGINE WAS SEIZED.