What was found
AIRCRAFT HAD JUST TAKEN OFF WHEN THE PILOT HEARD A LOUD BANG, HE TURNED AROUND AND LANDED AGAIN. UPON INSPECTION OF THE ENGINE, FOUND THE NR 4 CYLINDER WAS CRACKED AT THE HEAD JUST ABOVE THE THREADS WHERE THE HEAD AND CYLINDER ARE JOINED. CYLINDER WAS REMOVED AND REPLACED. HAD ENCOUNTERED THE SAME PROBLEM WITH NR 6 AND NR 2 ABOUT 160 HOURS EARLIER HAD TROUBLE WITH NEW PILOTS AND THOUGHT THIS WAS CAUSING PROBLEM. OVERHAUL WAS CARRIED OUT AT AERO RECIP, THEY WERE CONTACTED AND WILL BE INSTALLING 6 NEW CYLINDERS.