For those of us who reside in northern climates, it’s time for us to begin thinking about what we need to do to get our aircraft ready to put in the barn for the winter.
Certain recommendations also should be considered for aircraft that have less than regular use during the cold snowy months.
The first — and most important — thing we want everyone to be aware of, if you have any kind of engine heater, DO NOT leave it turned on all the time. This will cause more trouble than you would imagine.
For those of you who are not believers, consider this: When the heater is left on to keep the engine warm and toasty inside, think about the radical changes in temperature its outside experiences over a 24-hour period. If the aircraft is located in an unheated hangar, the temperature may vary from 0°F to above 40° F on any given day. While the internal temperature of the engine will more than likely remain close to a constant number, the outside of the crankcase will be exposed to a wide range of temperatures which, in turn, will cause condensation to form inside the engine. This is where the corrosion process begins and, unfortunately, there is no way to stop it from occurring.
If you have an engine heater and are able to fly your aircraft during the colder months, then follow the manufacturer’s recommendations regarding when and how to apply heat prior to your flights.
Let’s look at what to consider if the aircraft will be put away for the cold snowy months. First, take it out on a nice little flight that will allow the engine oil temperature to come up and stabilize for a short period of time, say maybe 20 to 30 minutes. Return to base and prepare to drain the oil. Even if your oil hasn’t accumulated the number of hours when you normally drain it, do it now anyway. By draining the old oil you’ll remove contaminates that are in the oil, getting them out of the engine.
You also want to inspect and clean the oil suction screen in the oil sump and remove, cut and inspect the oil filter as you normally would during a routine oil and filter change. Once you’ve completed this, you can reinstall the suction screen and install the new oil filter per the engine manufacturer’s recommendations.
At this point you’re ready to service the engine with fresh oil. Following this, I suggest you start the engine and check for leaks. Allow it to run for a few minutes to circulate the fresh oil throughout the engine. You are now ready to shut it down and continue the job.
Note: For those of you who may fly on occasion during the cold months, the aforementioned is still a good practice to follow because you will be getting the older, more contaminated oil out of your engine, which is much better than having dirty, contaminated oil sitting in it during extended periods of inactivity.
Once you’ve pushed the aircraft back into the hangar, I suggest you make two signs from brightly colored stock so everyone will see them. In big, bold letters, write: “”Do Not Turn Prop.”" While some of you will say, “”Hey, I want to pull the prop through once in a while during the winter so I can move the oil around inside the engine,”" that isn’t a good idea. If you stop to think about it, when you pull the prop through, you move the pistons up and down inside the cylinders and this is not something we want to do if the aircraft is not going to be flown. The result is that you may be wiping the oil off the cylinder walls, resulting in a greater chance for corrosion to begin, so just leave the prop stationary.
Cover the intake or inlet to the air box with duct tape or something similar. You must be certain that this covering is well marked and it must be removed before starting the engine. Put foam rubber balls in the exhaust pipes and again make certain they are well marked to be removed before starting the engine. Doing these simple things prevents outside air from getting into the engine, hopefully reducing the possibility of air mixing with moisture, which allows corrosion to start.
Be advised that I am aware of no procedure that will give you 100% protection against internal corrosion during a period of inactivity, but these few simple steps will at least offer some protection — and anything is better than nothing at all.
If you are going to fly during the colder months, you can still follow these suggestions. All you need to do is omit the oil and filter change each time you fly. Just remove the protection items and go fly. When you return, simply reinstall the items and go home.
Whatever you’ve heard in the past about starting the engine and ground running it during the winter, forget about it — unless you really want to risk doing harm to your engine. The only thing you will accomplish by ground running your engine is to promote condensation internally, which leads to corrosion. It’s impossible to get the engine oil temperature hot enough while ground running to cook off the condensation and other contaminants in the oil that cause the problems.
Paul McBride, recognized worldwide as an expert on engines, retired after almost 40 years with Lycoming. Send your questions to: AskPaul@GeneralAviationNews.com.