Read the owner’s manuals for several aircraft, and you’ll discover cold-weather starts are different for each engine, but there are some fairly universal rules to follow during cold start attempts. Some pilots refuse to move prop blades under any circumstances, but I always pull them through several times to break any possible hydraulic lock. Fuel is reluctant to vaporize in cold weather, and you’ll need to prime the engine(s) more than normal if you expect to start on the first or second try, an important consideration when two tries may be all you’ll get.
Don’t be overly enthusiastic about priming in cold weather, however. Limit engine cranking to no more than 15 seconds at a time. Remember, too, that constant speed prop mechanisms are oil-operated. Oil in the prop hub may have congealed, and you may need to let it warm up before you can expect the prop control to function.
Managing engine power after start can require you to split the difference between idling too slowly (which can ice the plugs) and too fast (which, as mentioned above, can score cylinders and cause ring damage). Keep power high enough so the engine runs smoothly, but not so high that you compromise lubrication with the cold oil. Most bush pilots recommend leaving cowl flaps closed in bitterly cold weather, especially during the warmup. The last thing you need during a start at -20 degrees F is a higher volume of cold air sucked through the cowling.
Avoid fast taxiing to keep from coating the wheels and brakes with snow and ice. If conditions are truly slick, you might consider doing the run-up and much of the power-up phase of pretakeoff checks on the roll to avoid losing control of the airplane in the run-up area. Just make certain you don’t lose control on the taxiway.
It’s axiomatic that directional control on a snow-covered runway can be trickier than on dry asphalt. Accordingly, avoid using braking for directional control, especially on patchy snow and ice. Let a locked wheel slide off glare ice onto dry pavement, and you may be sideways faster than you can think about it. During the takeoff run, use pure nosewheel/tailwheel steering until the rudder gathers enough aerodynamic authority. If there’s a crosswind that normally would demand differential braking for directional control, consider offsetting the nose an appropriate amount left or right of centerline before initial power-up.
Anything that increases rolling friction extends takeoff run, and snow can be a particular problem because it also affects directional control. Even if the runway is smooth and level, but covered with a flat layer of snow with no ice underneath and the wind is calm, expect the takeoff run to be at least 20 percent longer. Soft-field technique should be used just as you would on a grass strip, i.e., lift the nose or tailwheel off early to reduce rolling friction. You’ll want to get the airplane into the air as quickly as possible so you can accelerate quicker and climb away.
If you’re departing from a slushy runway in a retractable, you also should consider leaving the wheels down for a few seconds after liftoff to blow accumulated snow off the gear legs and out of the wells so it won’t freeze into ice in the cold temperatures aloft.
Engine temperature management in extremely cold weather can be daunting. Just as it’s often difficult in hot weather to keep engines from overheating, it may be a challenge to keep the cylinder heads warm in winter. Quite often, you can leave cowl flaps closed for the entire flight, and experienced-cold country aviators suggest using Vy for climb rather than cruise climb speed to reduce airflow through the cowling.
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