What was found
FUEL STAIN ON OUTER ALUMINUM CASTING, CRACK FOUND BETWEEN COOLING FINS NEAR UPPER SPARKPLUG HOLE AND FUEL INJECTOR PORT. CRACK CONFIRMED BY PRESSURIZING INDUCTION SYSTEM AND SOAP BUBBLES. CRACK ORIGINATED IN THE INTAKE PORT AREA. THIS IS THE 3RD CYLINDER REPLACED ON THIS SET OF CYLINDERS. THE LAST CYLINDER SEPARATED DURING FLIGHT, (NR 5 POSITION), CAUSING LOSS OF POWER AND FORCING AN EMERGENCY LANDING. THE FIRST CYLINDER FAILED LEAK DOWN TEST, (NR 4 POSITION), (LEAKAGE WAS DUE TO EXHAUST VALVE).