What was found
AIRCRAFT OWNER REPORTED SEVERE VIBRATION. AFTER INSPECTION IT WAS FOUND THAT SPINNER BULKHEAD WAS SEVERELY CRACKED. AFTER FURTHER INSPECTION NR 1 CYLINDER WAS FOUND TO BE CRACKED ALL AROUND THE CIRCUMFERENCE OF THE CYLINDER DIAMETER. THE CRACK WAS RIGHT AT THE 9TH AND 10TH COOLING FINS. THIS CYLINDER HAD A TOTAL TIME OF 355 HOURS SINCE NEW. THIS CYLINDER, DUE TO IT'S IDENTIFICATION MARKINGS DID NOT APPLY TO AD 2004-8-10, HOWEVER IT DID APPLY TO ECI'S MSB 06-2 WHICH IDENTIFIES THIS CYLINDER FOR INSPECTION FOR CRACKS. THE AD 2004-8-10 SHOULD PROBABLY INCLUDE ALL CYLINDERS IN ECI'S MSB 06-2. THE CONDITION WAS REPORTED IMMEDIATELY AFTER TAKEOFF AND THE PILOT RETURNED IMMEDIATELY TO THE AIRPORT AND LANDED UNEVENTFULLY. WHEN DISASSEMBLING TO REMOVE THE CYLINDER, THE CYLINDER ASSEMBLY CAME OFF IN 2 PIECES, THE CRACK WAS SEVERE AND WENT ALL THE WAY THROUGH THE CYLINDER WALLS RIGHT WHERE THE CYLINDER BORE AND THE COMBUSTION CHAMBER MEET.