In the scene where the helicopters are flying and the fuel lines(that were inside) freeze, wouldn't the men freeze first instead of freezing when they cracked the doors. The last time I checked fuel froze at a far lower temperature than blood, as they mentioned in the show that fuel freezes WAY WAY below zero.
I don't know much about helicopters, but it's probable that the fuel tanks were on the outside - having them inside, right next to the engine or whatever, would be quite dangerous. The engine is usually in a compartment; therefore, a line would have to run from the outside to the inside of the chopper - exposing it to the chilled air.