What was found
04/26/2011, OWNER FLYING AIRCRAFT, RECEIVED WARNING INDICATION/OVER TEMP ON 3RD CYLINDER. MADE UNSCHEDULED LANDING. UPON INSP, FOUND HOLE IN TOP OF CYLINDER ADJACENT TO SPARK PLUG. REMOVED AND REPLACED CYLINDER. VISUALLY INSPECTED OTHER CYLINDERS- NO DISCREPANCIES NOTED. 05/12/11- AIRCRAFT FLEW 25 MORE HOURS- PILOT COMPLAINED OF BAD SMELL IN COCKPIT; INSPECTED ENGINE, PERFORMED COMPRESSION CHECK NOTED NUMEROUS COMPRESSION LEAKS FROM 5 REMAINING CYLINDERS. (ENGINE HAD BEEN OVERHAULED AT 441 TT HOURS, NEW CYLINDERS HAD 404 HOURS ON CYLINDER NR3 AND 429 HOURS 5 REMAINING CYLINDERS). MFG IS REPLACING ALL CYLINDERS. CYLINDER PN: AEC631397, SN'S: 63931-05, 64015-20, 64010-04, 64506-08, 64506-12, 64526-15.