Winterizing Your Aircraft

While we've had a very mild fall here in Virginia, I recently met a student for a morning training flight, and the temperature was 26 degrees.  It was a nippy reminder that winter is just around the corner.  Now I love winter flying.  I have a heated motorcycle suit that keeps me nice and toasty, but most pilots put their planes away during the winter.  If I have any aircraft in inventory or that I am storing for a customer, those planes need winterization.  The thing about machines is, they don't really like sitting around.  You need to prepare them properly, if you want them to be there for you in the spring.

Fabric Wings

Usually when you read an article on winterization, the focus is on the engines.  That was where I was going to start too until I remembered friends with rodent-damaged wings.  During the winter rodents are looking for warm, cozy places to build their winter nests.  For some reason Dacron wings are very much to their liking.  It is bad enough that they nest in the wings, but they also chew -- a lot. I don't know if they like wings made of PX material, but I wouldn't want to take a chance and would protect them the same way.

The most important thing is to put the wing somewhere physically difficult for rodents (and/or birds) to get to it.  If you are folding your wing up you need to get it off the ground and make sure that rodents cannot climb up or down whatever is supporting it.  While I don't appear to have a rodent problem in my hanger, I still protect any wings I am storing.  I have a trailer that is fully sealed that I place my wings in.  Other ideas I've heard used successfully are:

• Hanging the wing from the ceiling via cables and putting an obstruction on the cable, like a disc, that keeps rodents from climbing down the cables and getting on the wing.
• Putting the wing up on saw horses and putting the legs of the saw horses inside of pails; again, with the intention of making it hard for rodents to get to the legs and climb up.  I thought filling the pails with water would be a good idea, but once the water freezes, rodents can get to the sawhorse leg and climb up.
• Surround your wing with traps or poisonous baits to kill the little suckers before they get to your wing.

Anyway, you get the idea.  When winterizing your aircraft don't forget to protect it against rodents and birds.

2-Stroke Engines

2-Stroke engines need to be protected against moisture and the associated corrosion issues.  Unlike 4-stroke engines, a 2-stroke's crankshaft is exposed to the elements.  Also, it gets its lubrication from oil-soaked gas.  Over time the gas can evaporate and take the oil with it, leaving your crank and bearings unprotected.  Additionally, if you have been using gas with alcohol in it, you may have introduced moisture into your engine via your fuel.  Here is what Rotax recommends if you are going to be storing your engine:

• Get your engine up to normal operating temperatures by letting it run at an increased idle speed, then shut it down.
• Next remove your air filters and inject about 6 ccm (1 squirt) of preservation oil into the air intake of each carb.
• Restart your engine and run at increased idle speed for 10-15 seconds.
• Remove the spark plugs and inject about 6 ccm (1 squirt) of preservation oil into each cylinder, then rotate the prop by hand 2-3 turns to lubricate the engine.
• Replace the spark plugs.
• Drain gas from the carb float chambers, fuel tank, and fuel lines.
• Drain coolant from liquid cooled engines if freezing is a concern (depends on your coolant and how cold your plane is going to get).
• Close up all engine openings such as the exhaust pipe, venting tube, and air filter to prevent entry of humid air and contamination.
• Lubricate linkages and spray external engine parts with oil (Rotax says "engine oil" but I use WD-40).

4-Stroke Engines

Rotax 4-strokes are much more resistant to moisture related corrosion for a number of reasons.  First, the lubrication system is completely separate from the fuel system -- the oil is not mixed with gas.  Consequently, you don't have to worry about the oil evaporating and leaving parts dry.  Second, the crankcase is not open to the environment like that of a 2-stroke.  Finally, the cylinder walls of Rotax 912 engines have a special coating which makes them impervious to corrosion.  Even so, there are steps you can take when your engine is going to be out of service for an "extended" period of time.  Rotax recommends:

• Run the engine until the oil temperatures have stabilized between 122-160° F (should be 5-10 minutes depending on outside temps).
• Switch the engine off and allow it to cool off.
• Change the oil.
• Remove the air filters and then start the engine.  With the engine running at increased idle squirt approximately 2 fluid ounces of corrosion inhibiting oil into each carburetor, then shut off the engine.
• Drain both carburetor bowls.
• Oil the carburetor joints.
• Close all engine openings such as exhaust end pipe, venting tube, air filters, etc.
• Spray steel external parts with rust inhibiting oil.

When you put your 912 back into service all you need to do is:

• Remove the plugs you used to cover the engine openings.
• Remove the spark plugs and clean with plastic brush and solvent, then re-install them.
• Provided your engine has not been stored for more than a year, you do not need to change the oil.
• Fly and have fun :-)

Summary

Whether you are flying a 2-stroke or a 4-stroke, the procedures to store your engine properly are not onerous and are worth the peace of mind you'll have when you start flying again in the spring.  Better yet, skip the preservation exercise all together, get out your warm clothing, and discover winter flying :->.

Cheers,
Terri