What was found
AFTER TAKEOFF/CLIMB NOTICED VIBRATIONS TURN BACK TOWARDS FIELD RETARD THROTTLE AND HEARD A BANG AND WINDSHIELD AND CANOPY COVERED IN OIL EMERGENCY SHUT DOWN. WAS ABLE TO LAND WITHOUT FURTHER INCIDENT. AFTER LAND NOTICED SPINNER/PROP AND PROP FLANGE MISSING UPON FURTHER INSPECTION NOTICE THE CRANKSHAFT BROKE. (THIS IS AN EXPERIMENTAL AIRCRAFT AND ENGINE). ENG: VW 2180, AIRCRAFT: AMTR CX4