A number of years ago got to lookat transport Canada's flight check Dash 8. They carried a whole set of intake and exhaust covers and ladders to secure the a/c when the had no RON at fun places like Churchill, etc.
The PT-6,as I understand it, is a reverse flow engine when mounted in the aviation appliciation (it was originally designed as a stationary power plant) so it would not be unexpected that a lot of ice/snow could build up. Is the rest of the PWC family of engines also "reverse flow"?