As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UPON DISASSEMBLY FOR ITS FIRST OVERHAUL, THE TECH FOUND TAPERED PIPE PLUGS WERE INSTALLED IN CRANKCASE INSTEAD OF THE REQUIRED PISTON COOLING JETS. PISTONS AND CYLINDERS SHOWED SIGNS OF OVERHEATING ALTHOUGH NO MALFUNCTION OCCURRED. ENGINE RECORDS INDICATE THE ENGINE WAS BUILT FACTORY NEW, INSTALLED ON AC AND HAS HAD NO HISTORY OF CYLINDER REMOVAL OR REPLACEMENT.