What was found
(CAN) AIRCRAFT CAME IN FOR 100 HOUR INSPECTION WITH ENGINE OIL LEAK UPPER LT SIDE. ON GROUND RUN ENGINE VIBRATION WAS EVIDENT, MAG CHECKS WERE NORMAL, ONCE COWLINGS WERE REMOVED IT WAS DISCOVERED THAT THE CYLINDER HEAD OF NR 1 CYLINDER WAS LOOSE ON THE BARREL. FURTHER INVESTIGATION REVEALED THAT THE CYLINDER HEAD HAD COMPLETELY SEPARATED FROM THE CYLINDER BARREL. ASSY WAS REMOVED AND REPLACED WITH SERVICEABLE CYLINDER ASSY. (TC NR 20070921003)