What was found
ENGINE BECAME ROUGH DURING FLIGHT. UPON LANDING AND INSPECTION, IT WAS DETERMINED THAT CYLINDER NR 4 WOULD NOT PASS CYLINDER LEAKAGE TEST. AFTER FURTHER INSPECTION, CYLINDER WAS FOUND TO BE CRACKED ONE-HALF WAY AROUND CIRCUMFERENCE BETWEEN FINS AT JUNCTION OF HEAD-TO-BARREL. CYLINDER WAS REPLACED AND ENGINE WAS RETURNED TO SERVICE. CYLINDER WAS BORED .010 INCH. ENGINE TT, 2,344.8 HRS. ENG SMOH, 319.8 HRS.