Aircraft Maintenance: Cold weather operations

Keeping your aircraft safe during the winter can be a challenge, especially if you’re parked outside. The best defense is a set of high-quality aircraft covers for the fuselage, wings, and tail. Removal of snow and ice is much easier, and aircraft covers will protect the paint and control systems from ice damage. It is also important to protect the aircraft from excessive snow loads by using a tail stand to prevent your “nose dragger” from switching to a “tail dragger” when snow accumulates on the elevator. At the very least, be sure to put a few tires under the tail to provide a soft landing if it does rotate down.

It is critically important to understand and accept that no amount of snow, ice, or frost contamination of the exterior of the aircraft is acceptable prior to flight. Even the lightest coating of frost or residual ice on the wings or control surfaces can have a dramatic effect on the lifting ability of the wings and the handling qualities of the aircraft.

Without question, the safest and most thorough method of clearing the aircraft is to move it into a heated hangar long enough to melt all snow and ice; then dry the residual water before moving the aircraft back out into the cold. This last step is critical. The resulting meltwater can migrate into hinges, spinners, control surfaces, brakes,  and elsewhere. If the airplane is moved back out into the cold before drying, it can freeze and create dangerous imbalances or even obstruct control surfaces.

If you don’t have access to a heated hangar, your next best option is to use some form of deicing fluid. One reasonably priced solution is the pink recreational vehicle plumbing antifreeze available at most hardware stores.  There are several varieties available, most made from a blend of propylene glycol, alcohol, and anticorrosion additives. Such mixtures are typically environmentally friendly, but be very careful to research the ingredients to make sure they are safe for aluminum and test for paint staining on an inconspicuous part of the aircraft prior to use (especially on composites). For an easy application method, use a garden pump-style sprayer. And as always, don’t forget to manually dry the aircraft prior to flight.

When it comes to aircraft windows, try to avoid using chemicals unless they are specifically approved for Plexiglas. Warm water is often the best solution if outside temps are above freezing, but be careful to apply it lightly so as not to “shock cool” the plastic. Spraying or pouring hot water onto a cold windshield is a sure way to induce a crack. Most importantly, avoid scraping ice and snow from the aircraft at all costs. Credit cards, scrapers, and even brooms can scratch the paint and windows. Take your time to gently allow ice and snow to release on its own, so you don’t regret your actions come springtime. Lastly, be sure to remove the wheelpants if your typical winter flying includes slushy taxiways and runways. These can easily fill with ice and snow, leading to cracking and potential safety issues during landing.

Preheating should be thorough and used only when needed. Using an engine blanket and a complete heating system such as the Tanis system will ensure that the warm and moist air from the heated parts of the engine does not condense on any colder components, bringing with it damaging acids from the used oil, accelerating the corrosion process. Corrosion is a temperature-sensitive chemical process. At low temperatures, corrosion proceeds slowly. This makes winter a safer time for an aircraft to be idle for longer periods. However, if you leave a preheater on for long periods of time, you are creating an ideal environment for corrosion to accelerate as the heat and moisture combine. Utilizing on-demand preheating, along with an engine dehumidifier, such as the DryBot Automated Engine Dehydrator, is the best way to preserve your engine.

Lastly, take the time to do an especially thorough preflight during the winter. Every system on the aircraft—from the brakes, struts, and control systems and surfaces to the propeller and spinner, and even the avionics—needs to be checked to ensure that it is functioning properly and unaffected by cold or ice. Ice, for example, can collect inside the spinner, causing a serious imbalance. Inspect the spinner with care, and be ready to shut the engine down if you feel a suspicious vibration upon startup. Ensuring that you have checked every system before you take off is extremely important to mitigate the risk of malfunctions related to ice, snow, and temperature. Once airborne, be sure to monitor engine performance, temperatures, and pressures. If the oil temperature is not getting hot enough to register in the green range on your gauge, you may need to install winter baffles or partially cover your oil cooler (as recommended by the engine or aircraft manufacturer).

Protecting your airplane and getting it ready for flight can be challenging during the winter. However, with careful preparation and a thorough preflight ritual, winter flying also brings improved performance, stable air, and great views of the winter wonderland below. Until next time, I hope you and your families remain safe and healthy, and I wish you blue skies.