It was apparently a ferry flight according to one report I read. Not the best route at this time of the year. Intense cold is hard on piston engines. I never fly my Beech below -15C. Of course I have to pay my own engine overhauls. A nice whiskey near the wood stove is my activity of choice in the deep cold...
Might be ice in the fuel as well, we'll never know, the plane is at the bottom of the Arctic Ocean.
Beech