What was found
AIRCRAFT MADE AN EMERGENCY LANDING DUE TO PROBLEM WITH LT ENGINE. 1) INVESTIGATION REVEALED NR 5 CYL TOP 4 CYL HOLD-DOWN STUDS SHEARED OFF AND MOVEMENT OF CYL TOP AWAY FROM ENG CASE CAUSED A LARGE CRACK IN THE ENG CASE COMING FROM LOWER CYL FLANGE AREA. 2) FURTHER INSPECTION OF ENG REVEALED UPPER FWD HOLD-DOWN STUD ON NR 4 CYL HAD BACKED OUT TO THE POINT WHERE IT CONTACTED A COOLING FIN OF CYL BENDING IT SLIGHTLY. 3) ENGINE REMOVED TO OVERHAUL FACILITY. FAA FORM 8020-2 AFFIXED TO ENG BY FAA INSPECTOR.