What was found
STUDENT AND INSTRUCTOR WERE FLYING, HEARD LOUD BANG. AC SHUTTERED, OIL PRESSURE STABLE, RPM DROPPED TO BOTTOM OF GREEN ARC, OIL PRESSURE STARTED DROPPING ON A PRECAUTIONARY APPROACH. NORMAL LANDING, SHUT ENGINE DOWN AT SOUTH BAY AVIATION. UPON INSP OF ENG IT WAS DETERMINED. NR3 CYLINDER HEAD SEPARATED FROM CYLINDER. REPLACED NR 3 CYLINDER ASSY.