If the operators are going to be doing any scheduled flying they may have hanger space available and if not they will use insulated cowling and wing/tail covers to keep the snow and cold back. Overnight the fluids would usually be drained and brought into the cabin/tent/shop to keep them from freezing within the motor. Next morning they would be put back into the motor and if it was really cold a heater tent would be set up to heat the engine compartment. Now on a lower 48 winter day the old boys may not even use the covers
, but I digress. If they are parked for the winter like most of the planes at Lake Hood are, then they are winterized much like a walleye/bass boat would be here in Minnesota and left to endure the bitter cold.