did I understand that in the Nordic countries, salt is not much used on the roads because it would be no use anyway, given the very low temperatures and the amounts of snow/ice?
Definitely not! Salt is used all the time. It’s apparently an EU regulation saying main roads should be black (no snow). Some 10-15 years ago salt was not used much, except in cities. The main roads were nice to drive, solid nice and light winter conditions. Today, the roads definitely have more traction, but the melting ice and snow mixes with dirt and becomes a salty, dirty slush. In the winter I use almost as much viper fluid to keep the window visible as I use fuel. Today (driving electric), I only use liters and liters of viper fluid 
It’s apparently an EU regulation
Well, that sounds like one more reason to sympathise with this pilot/owner/operator.
Salt is used from around +1 to -7 degrees. It’s really annoying, but apparently trucks and buses don’t use winter tires any more. Also, in major cities the traffic is just so heavy that slippery roads lead to chaos. Salt is mostly needed when temperatures hang around 0 degrees. Really cold temperatures produce nice grip and excellent winter flying and driving conditions.
I’ve seen in a couple of occations, both in Norway and France, in places with sub zero temperatures, hangared planes with a blanket over the engine “to protect from the cold”. What is the exact purpose of that? I can only see the blanket reducing the rate of cooling of the engine, but in a hangar, with an already relatively cold engine, I imagine shock cooling not being an issue, and much sooner than the end of the night, the engine will be at “hangar” temperature anyway.
So, I can’t see a point, but (as in other things in life), some smart people do it so there might be a reason I am missing (or they just didn’t think about it).
I agree your point that the engine will eventually chill down to ambient but I imagine those who use a blanket are concerned about the rate of chilling more than the ultimate depth of chilling.
Aero engines with their mix of metal components all with different rates of expansion/contraction might, I suppose, suffer if exposed to a sudden deep chilling with, say, the aluminium case contracting more, and more quickly, than the steel crankshaft within.
I have no personal experience of this, so this is my best guess, but a guess nevertheless.
I’d be VERY sceptical of the blanket making any difference in the effect (on components etc) of the cooling. If it were true, this would be really overshadowed by things such as turning off the engine on the ground.
Maybe the biggest effect is to show other people that the owner really babies his plane!
Perhaps they leave it there as a convenient place to store it until they preheat the plane with either a Tanis or Rieff system. Sometimes you can activate the system with a phone call. Perhaps they will be leaving in a few hrs and they dont want the engine to get too cold before they depart. Other than that I see no reason to do what they are doing.
C210_Flyer wrote:
Perhaps they leave it there as a convenient place to store it until they preheat the plane with either a Tanis or Rieff system. Sometimes you can activate the system with a phone call. Perhaps they will be leaving in a few hrs and they dont want the engine to get too cold before they depart. Other than that I see no reason to do what they are doing.
At least in France that wasn’t any of the cases. I can’t remember if in Norway (Tromso) they left the blanket on to use with the heater.
I think it makes them feel like they are doing something. Other than short term heat retention after landing or while heating I can’t see how it would help.
In really cold places the blanket is very common (or necessary!). In the prairies of North America the winter temperature is often minus 20 to minus 30 celcius in the winter. Imagine how quick an engine will get cold with a 30 km/hr wind blowing over it while it sits on the ramp (nevermind the pilot!!).
Normally you pull the plane out of the hanger (having been preheated) with the blanket on. This will give you half an hour of mucking around, i.e. fueling etc. Then you take the blanket off, start up and go. Obviously, the more you can do while still plugged in and heating in the hanger the better.
In relation to the blanket on the aircraft while it is in the hanger; The Reiff and Tanis systems can only put out so much heat… if it is really cold you need the blanket to keep the heat in while pre-heating.
Obviously if the heat is off, and the aircraft has been parked for a prolonged period it will come to equilibrium with the hanger (the blanket is doing nothing). But you might as well leave the blanket on the cowl, as you are going to need it when you start the pre-heat cycle.
It is also often hard to fold and unfold frozen blankets/engine covers. So it is easy to take the cover out of a warm aircraft, put it on the airplane while it is still pliable and put the airplane to bed after a flight. If you wait until the cover is frozen in the folded position it will be a pain when you come to aircraft the next time to start pre-heating.
