by Richard Morey
© Copyright 2021. All rights reserved!
Published in Midwest Flyer Magazine – December 2021/January 2022 Online Issue
Winter is a wonderful time to fly. Aircraft perform well in the crisp, dense air, so long as you can get them started! Here in the Midwest we are “blessed” with long and generally cold winter weather, which adds challenges that we do not have in warmer weather. With a little foresight, planning and adjusting your preflight actions, winter flying need not be a chore.
Dress for the weather.
Winter is cold. This seems a fairly obvious statement, but considering how some of my students dress for their winter lessons, it is not as well-known as it should be.
Simply stated, dress for the weather! Wear a winter coat, hat, gloves or mittens, long underwear, and boots that will not only keep your feet warm, but be up to walking through snow drifts if you have to make an off-field landing. Most aircraft have limited space in their flight deck. There just is not room to wear all the layers of cold weather gear in some aircraft. Placing your outer layers, such as heavy coat, boots and possibly snow pants in the back seat or baggage compartment, makes sense if you cannot fly comfortably with everything on.
Winter preflight inspections are similar to warm weather inspections in most areas, but have some cold weather specific items added. Snow, ice and the cold weather that brings them require a more careful approach to preflight. The following assumes that the aircraft is stored outside.
Be sure of your footing. Ice, snow, and especially black ice can cause slippery conditions. I have taken more than one nasty fall due to slipping on ice I did not see. Look over the area and be especially careful if you have a high-wing aircraft and use the fueling steps to check your gas caps and fuel level. It is awkward enough coming down from those steps, and downright dangerous if you are stepping onto a slick surface.
Frost, Snow and Ice
If there is frost, snow or ice sticking to your aircraft, you need to remove it prior to flight. If it is light or wet snow, you may be able to brush or leaf-blow it off. I really like using a leaf blower for this as brushes can damage the paint and have been known to take off ELT antennas. If the snow/ice/frost is not easily brushed off, then you need to deice. At our airport, that means pulling the aircraft into a heated hangar and letting it melt.
Do remove as much of the contamination as reasonably possible prior to deicing. Once deiced, if you are pulling the wet aircraft into cold temperatures, expect the remaining water to freeze. It would be smart to leave the flaps down for your runup and pull them up just prior to take-off. This minimizes the possibility of the flaps freezing in the up position. Also, double check that the static source and pitot tube are clear and have not iced over.
Brakes are another area that need special attention. I believe that wheel pants need to be removed for the winter. If you try to fly with the main gear wheel pants on, you will eventually have to deal with frozen brakes and wheel pants packed with snow. Even without wheel pants, aircraft brakes are prone to freezing up. Most pilots apply brakes far more often than they need to during taxi. This heats the brake discs. If you taxi through snow with a hot brake disc, you will melt the snow, which once you stop moving, could freeze the brake pads to the disc. During preflight, the best way to tell if the brakes are frozen is to kick the tire. With a high-wing aircraft, this is easy, especially if the aircraft has a wing strut to hold onto. Kick the tire as if you are trying to get it to roll. If you hear a snap, you just broke ice freezing the brake pads to the disc. If the wheel moves freely, you did not have ice. It is also possible to freeze up your brakes while taxiing. If you must taxi through snow, be sure to minimize the use of brakes.
I have had to exit the aircraft and kick the tires after a taxi through snow that resulted in frozen brakes. Be sure to shut the engine down prior to exiting!
Hydrophilic Oils & Frozen Brakes
Brake fluid and engine oil are hydrophilic – they love (phallic) to soak up moisture (hydro). This can be a problem for brake function on very cold days. As part of the preflight, brakes are tested by applying them prior to start up. There should be some give to the brakes until they come up hard. With toe brakes, the foot is flexed, and brake fluid compressed. If the brakes feel hard after some movement, they are likely good. If they feel spongy or soft, there could be air in the line or other issues. If they do not move at all, but rather are hard from the get-go, then the brake fluid has soaked up enough moisture to freeze. The ice formed blocks the brake line and does not allow the now solid brake fluid to do its job. There will be no braking action if this occurs. Do not start the aircraft if the brakes come up hard with no compression or movement. The aircraft now needs to go into a warm hangar to melt the frozen brake fluid/water mix. The old fluid will be completely drained and replaced with new.
Engine oil is hydrophilic as well. Water vapor is a byproduct of combustion, so there is a constant source of water vapor for the oil to absorb. When you heat oil, some of the water vapor evaporates. When the engine is running, this water vapor goes out the crank case breather vent tube. This is good, as having water in the engine promotes corrosion.
Most engine heaters work by heating up the oil in the oil pan of the engine. An electric heating element is bonded to the oil pan in standard installations. During this process, water vapor is released from the oil and moves throughout the engine, condensing in the colder areas of the cylinders and in Lycoming engines, on the camshaft. The best practice is to only heat the engine immediately prior to starting up if you have this type of heater.
Tanis-type heaters have heating elements on the oil pan, the cylinder heads and crank case.
If you have a Tanis engine heater, your problems with unwanted moisture during preheat are minimized. Still, I would preheat only prior to start up. One to two hours is generally sufficient, especially if there is a cowl cover or blanket wrapping the cowling.
Forced air heaters work by blowing heated air over the cylinders of the engine. These heaters work quickly, but do not heat the oil as efficiently as the electric heating elements do. At my flight school, we have and use all three types of preheaters. Our company policy is to heat the engine if the outside air temperature is below 30 degrees if the aircraft is sitting outside. The best preheater is a heated hangar. Alas, most of us cannot afford heated hangars, so we make do with what is available.
Dress for the weather.
Remove the aircraft’s main gear wheel pants.
Brush or deice the aircraft to remove all ice, snow or frost prior to take-off.
Pay particular attention to the aircraft static source and pitot tube for ice blockage.
Check your brakes for freeze up, both on the pad/discs and in the lines.
And finally, preheat the aircraft’s engine when the temperature requires, and for a reasonable time-period, prior to start up.
Safe Flying !
DISCLAIMER: The information contained in this column is the expressed opinion of the author only, and readers are advised to seek the advice of their personal flight instructor and others, and refer to the Federal Aviation Regulations, FAA Aeronautical Information Manual, and instructional materials before attempting any procedures discussed herein.
EDITOR’S NOTE: Richard Morey was born into an aviation family. He is the third generation to operate the family FBO and flight school, Morey Airplane Company at Middleton Municipal Airport – Morey Field (C29). Among Richard’s diverse roles include charter pilot, flight instructor, and airport manager. He holds an ATP, CFII, MEII, and is an Airframe and Powerplant Mechanic (A&P) with Inspection Authorization (IA). Richard has been an active flight instructor since 1991 with over 15,000 hours instructing, and almost 19,000 hours total time. Of his many roles, flight instruction is by far his favorite! Comments are welcomed via email at Rich@moreyairport.com or by telephone at 608-836-1711. (www.MoreyAirport.com).