What was found
ACFT HAD JUST DEPARTED ON PART 91 REPOSITIONING FLIGHT BACK HOME. APPROX 10 OR SO MINUTES AFTER DEPARTURE, WHILE LEVEL IN CRUISE FLIGHT AT 7000', RT ENGINE EXPERIENCED SUDDEN POWER LOSS. ENGINE WAS SHUTDOWN, PROP FEATHERED, AND ACFT RETURNED FOR LANDING. FOR UNKNOWN REASON, PISTON JAMMED IN CYLINDER, POSSIBLY DUE TO RING DEFECT, CAUSING THE BOLTS TO SHEAR AND THE CASE TO CRACK. THERE WAS NO EVIDENCE OF OIL LEAKS OR OTHER ABNORMALITIES PRIOR TO THE OCCURENCE.