the pilot then initiated the spin recovery procedures to no apparent effect through about 9 rotations, and stated that the roll rate was a lot more rapid than the first spin event. He then pulled both propeller controls levers to the feather position and was able to get out the spin.
Feathering both propellers appears to be the key to a successful recovery under the stated conditions at the time. Clearly the pilot would have a sound reason for feathering the props. Can anyone suggest that reason?