What was found
WHILE PERFORMING 100 HR INSPECTION OF AIRCRAFT, FOUND CRACKS IN CYLINDERS: NR 3 LOCATION, SN60652-27, NR 5 LOCATION, SN 60652-25, NR 4 LOCATION, SN 606652-23. CRACKS WERE FOUND IN THE HEAD CASTING ON THE INTAKE VALVE SIDE IN THE VICINITY OF FINS 15-17 AS COUNTED OTBD FROM THE HEAD/BARREL JUNCTION. ENGINE WAS MODIFIED IAW STC SE4327SW-D. CRACKS WERE DETECTED VIA SOAP BUBBLE TEST, EXCEPT THAT NR 5 CYLINDER HAD AUDIBLE HISS DURING COMPRESSION TEST AND HOLE BURNED IN BAFFLING.