One last question. Was this "turbine wheel" that failed in the hot or cold section? Either or, if it failed and the Prop didn't Autofeather (worse case scenario) the propeller blades would indeed still "windmill." Still "turn." They would however not be under full power. There are distinctive "tell marks," a prop/engine under full/partial/no power makes when it hits the ground/a tree/etc.....
I studied this in college, have a degree in Aviation safety. I know a few folks that have been on or are on the Go team or are ASI's across the country. This isn't NHSTA or some committee put together by Lobbyists. These folks know what they are doing. There is a reason other countries ask the NTSB to assist in crashes. They are one of the few things in this country "big government" got right.
RadialGal