As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
A CYLINDER WAS REMOVED DUE TO OIL FOWLING OF THE SPARK PLUGS. A CHUNK OF METAL WAS MISSING FROM THE PISTON. REMOVED THE OTHER 3 CYLINDERS AND FOUND 3 OF THE 4 PISTONS WERE DAMAGED IN THIS WAY. ALL CYLINDER COMPRESSIONS TESTED GOOD, MID 70/80.