What was found
DURING FLIGHT, CONTROL SHAFT NUT BACKED OUT CAUSING LOSS OF ENGINE OIL AND SUBSEQUENT ENGINE DESTRUCTION. IT HAS BEEN DETERMINED THE CONTROL SHAFT GASKET WAS NOT PROPERLY BENT TO PROVIDE A MEANS TO SAFETY THE CONTROL SHAFT NUT TO PREVENT IT FROM LOOSENING/BACKING OFF. ITEM 18, PN B-4739, IN HARTZELL MANUAL.