As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) HOT CYLINDER DIFFERENTIAL COMPRESSION CHECK CARRIED OUT AND FOUND ALL CYLINDER COMPRESSIONS WELL BELOW MINIMUM ALLOWABLE. VIDEOSCOPE INSPECTION CARRIED OUT, AND FOUND ALL CYLINDER INTERNAL WALLS HEAVILY CORRODED IN THE CHOKE PORTION OF EACH CYLINDER.