Aircraft Winter Operations Tech

Aircraft operations during the winter months requires more planning and technology than the other three seasons.  Cold temperatures, snow and ice, play havoc with airframes, aircraft engines, avionics, gyros and people.  A heated hanger is a silver bullet, typically keeping the aircraft at a toasty 10 to 15C or more.  Canadian bush pilots operating procedures differ than those in the lower 48. Before the era of engine heaters, bush pilots would drain the oil from their radial engines, keeping the oil warm over night in their wood fired cabins.  

Lycoming recommends that preheating is required when the temperature is at or below -17C.  Many pilots/operators use their best judgement as to when to pre-heat, however, I pre-heat once the outside air temperature (OAT) dips below +5C, for a minimum of 3 hours. Many pilot/operators leave their aircraft plugged in and heating all winter, while others believe that preheating before you fly (or the night before) minimizes the probability of corrosion to the engine.  There are a three types of pre-heaters: electric forced air; propane forced air; electric using bands, pads and probes.  Companies like E-Z Heat, Hornet, Safe-Heet; Tanis; Reiff; and AeroTherm manufacture preheaters. 

Take-off demands 90-100% of an engine’s horsepower, and for this reason, it’s vitally important to properly warm the engine. Proper pre-heating reduces wear and tear and substantially extends the life of an engine. Idling is not an effective way to warm an engine. When idling, the propeller forces cold air back across and through the engine compartment keeping a cold engine from heating properly.

Tanis and Reiff manufacture engine heaters and related accessories designed to preheat the engine, cabin and battery and are powered by 110 or 220 AC connections. Both manufacturers have similar technologies designed to provide consistent heating with a variety of components: oil sump pads; heated cylinder probes; heated cylinder bands; wiring harnesses; on/off lights; cabin heat pads; and thermostats. Reiff utilizes a 3/8" wide stainless steel clamp placed around the cylinder acting as a band heater, while Tanis uses cylinder probe heating elements. Kits start at $1150 CND, plus installation.

Thermostats are used to prevent overheating while the engine heater is operating. Reiff’s cylinder heaters do not have a thermostat control, but some of their oil heaters do. While an engine is running, the cylinder normally reaches 300-350oF.  Cylinder heaters increase temperatures to  70-90oF over ambient air temperature, so there is no danger of overheating the engine. Oil sump heaters are sized to raise the temperature of the oil up to 100oF above ambient, and a thermostat on some systems further limits the oil to about 190o. This means in normal winter use the thermostat never cycles, it just stays on. This design approach gives you the benefit of a thermostat controlled maximum oil temperature, without the disadvantage of limited thermostat life due to constantly cycling on and off.

Many Canadian FBO’s have propane heaters to preheat the engine, which produce high BTU's, transferring heat to the cylinders via the cooling fins. With hoses tucked into the cowling, heated air is blown into the engine compartment, typically taking 20 to 30 minutes, depending upon the OAT.  Warm cylinders are all you need if your only goal is to get the engine started.  To avoid damage and wear to the engine from cold starting, the entire engine and the oil needs to be uniformly heated, typical a 20 to 30 minute blast of hot air may not be enough.

AeroTherm manufacturers a forced air electric heater. Designed to hang off the prop and using thermoplastic ducts, it pushes heated air at 32 mph into the engine compartment.  With a variety of models, the compact system weights between 9 and 15 lbs making it ideal to travel and costs between $599-$979 USD.

Many pilot/operators do not keep their engine heaters powered 24x7.  Cellular or Wi-Fi controlled power switches are used to remotely turn electrical power on/off.  There are a variety of options: pager controlled; cellular dial up; cellular data with an App;  IP controlled (WEMO) using Wi-Fi. Companies like SwitchBox and FST LLC (Regal Pro) have hardware and apps which use a cellular data service to control when power is turned on/off.  Typically priced between $485 and $535 CND.

Winter operational requirements will vary based upon the specifics of geography.  Winter conditions in Toronto, Yellow Knife, Halifax, Iqaluit and Victoria vary greatly. For aircraft parked outside, wing/tail covers and thermal engine covers are recommended to aid in removing snow and ice quickly, while keeping the engine preheater’s heat at an optimal temperature.  

Winter flying provides an environment which dramatically improves the performance of most general aviation aircraft.  To provide a safe environment for both aircraft and people more planning is required, rewarded by an outstanding experience.