Winterizing airplane

[MMontoya]

I fly an open cockpit AcroSport II in Colorado. I am at the end of my flying season, and am interested in thoughts on winterizing the airplane. Over the years, I have spoken to several mechanics, and airplane owners on what they do to store an airplane for about 5 months.

Some folks have recommended everything from draining fluids, to just putting the battery on a trickle charger, to running the airplane every couple of weeks or so. Colorado is a dry climate, which, I am sure, makes a difference in how one stores an airplane. As for running the airplane periodically, I have tried to fly when it is 40 F before, and I have only made it about I trip around the pattern before I had to land and thaw out, and the engine didn't get up to temperature. I am thinking that running the airplane on the ground periodically in the winter does more harm than good.

Thanks,

Mike

[FlyingRon]

Your option is to properly store the engine (which involves changing and putting fresh (dry) oil NOT draining it, fogging the cylinders and putting in desicant plugs) OR get out every few months and fly it.
Just starting it up and running it up on the ground is going to do more harm than good is correct.

[rosiejerryrosie]

I'm interested in why your both think running it on the ground will do more harm than good. If the engine is run until it is up to operating temperature, how does the engine know if it is three feet or three thousand feet above ground?:)

[DanChief]

Jerry -- these air-cooled engines are meant to have air flowing over them. When we sit and run them on the ground, the heat is concentrated on certain spots, causing uneven heating. Also, we don't run them at full power on the ground, so they never reach true operating temperature.

I try to be airborne within 10 minutes of startup. It's not always feasible (KTEB, for example), but is best for the engine.

For winter flight in the Chief I cover certain cowl openings with aluminum tape. The engine temps stay in the green and I actually get some cabin heat!

[Joe LaMantia]

I'm no expert, but from what I've read and been told the biggest problem with long term storage is rust. Ron's suggestions are in-line with several articles that recommend desicant plugs, short time run-ups only end up adding water to the engine oil and increasing the probability of rusting. I think you might do well to do a "search" of this subject for previous articles in "Sport Aviation", this problem has been with us for a long time.

Joe
:cool:

[rosiejerryrosie]

Jerry -- these air-cooled engines are meant to have air flowing over them. When we sit and run them on the ground, the heat is concentrated on certain spots, causing uneven heating. Also, we don't run them at full power on the ground, so they never reach true operating temperature.

I try to be airborne within 10 minutes of startup. It's not always feasible (KTEB, for example), but is best for the engine.

For winter flight in the Chief I cover certain cowl openings with aluminum tape. The engine temps stay in the green and I actually get some cabin heat!

I'm confused, Dan. " these air-cooled engines are meant to have air flowing over them" but "For winter flight in the Chief I cover certain cowl openings with aluminum tape." Dosn't the tape stop some of the air?

I have, in the past, run the Continental on the ground, facing into the wind, until I reach operating temperature. In the winter, it usually takes some time to reach that point. It would seem that facing into the wind and the 'prop wash' provides a significant amount of cooling - to the extent that it takes much more than 10 minutes to reach operating temperature. Do we have a valid point here or is this a long standing 'aviation old wives tale'....:)

[rosiejerryrosie]

Joe, I agree that rust (moisture) is the real culpret, and desicant plugs and cylindar fogging are the best approach, but if I run my engine until it reaches operating temp, I have been led to believe that 'burns off' accumulated water (moisture) that would lead to rusting. How would increasing the temperature lead to more water? If it is thought that the cooling after a good runup to operating temp causes water to condense, how come it doesn't happen in the summer when we are running the engine more frequently? Or is it thought that the more frequent run ups burn off the moisture before it has a chance to induce rusting? If that it the case, more frequent runups in the winter should accomplish the same thing - but, with the cost of fuel these days, desicant plugs and fogging would be considerably less expensive.

[Dave Stadt]

Joe, I agree that rust (moisture) is the real culpret, and desicant plugs and cylindar fogging are the best approach, but if I run my engine until it reaches operating temp, I have been led to believe that 'burns off' accumulated water (moisture) that would lead to rusting. How would increasing the temperature lead to more water? If it is thought that the cooling after a good runup to operating temp causes water to condense, how come it doesn't happen in the summer when we are running the engine more frequently? Or is it thought that the more frequent run ups burn off the moisture before it has a chance to induce rusting? If that it the case, more frequent runups in the winter should accomplish the same thing - but, with the cost of fuel these days, desicant plugs and fogging would be considerably less expensive.

It takes a considerable amount of time once the engine is up to temp to get rid of all the moisture. Just getting up to temp will not do the job and just because the oil is up to temp doesn't mean the entire engine is at operating temp. Good rule is if you start the engine fly for at least an hour.

My Operation Manual says to avoid long ground runs. I figure they know what they are talking about. The rear cylinders certainly are not getting much cooling air if you are doing extended time, high power ground runs. I would think the rear CHTs would get quite high.

[Bill Greenwood]

Mike, as Ron says , fresh oil change, and you might run some Marvel Mystery Oil in the gas on one last
flight after the oil change, ,maybe spray some Marvel or engine or best yet preservative oil on the clyinders. May not need desicant plugs, can''t hurt.
DONT RUN UP ENGINE UNTIL YOU ARE READY TO FLY. Oil companies say it takes 15 min or so of inflight temps to get any water out of the oil.
I stored a acro biplane, Rose Parakeet , open cockpit , one winter in Crested Butte, did nothing to preserve it and had not problems in the spring, at least as far as I know.
I am in Aspen and Boulder, where are you?

[Joe LaMantia]

Good Topic!
Here's a bit more on my take regarding water. When you run your car or airplane engine it gets warmer then the outside air and yes it will get rid of water and fuel that has diluted the oil in the crankcase. When you shut it down, the moisture in the air, will condense and a bit will wind up back in the crankcase along with a bit raw fuel. There are at least 2 issues here, first the humidity available and second the amount of time the new dilution gets to sit before you run the engine again and burn it off. The humidity is generally lower in winter than sumer and certainly a lot less out west then the rest of the country so that issue may not be a big deal for a plane sitting in Colorado or Arizona. I just got back from a 3 week trip out there and saw humidity levels as low as 22%. Those of us from the Mid-West consider a "dry" day around 60%. My personal flying season runs from March to the first snow fall which is usually around Xmas. I think that is pretty typical of a Mid-West private pilot, so we're talking about a 3-month period of sitting. If I owned my own aircraft and didn't have a heated hanger I would do the oil change thing and maybe fogged the cylinders with WD-40, then use the plugs. I wouldn't bother with starting the engine and warming it up unless I was actually going to fly it on a regular basis. This is pretty much in-line with Bill's comment, I would use the desicant plugs maybe even go so far as to build a simple dry air pump. I saw an article in Sport AV on that subject not all that long ago, they even had a home-built little kit that was pretty good at keeping condensation low and engine rust away!

Joe
:cool:

[DanChief]

Jerry -- some of the cowling openings are taped over in winter (usually the hole in front of the oil pan). There's still plenty of air coming in through the main eyeballs on either side of the prop at my insanely high speed flight of 70-80 MPH.

:D

As you probably know, the O-145 is a cool running engine. In temps below 35 it rarely gets the oil warm enough to ensure all moisture is boiled off. (I also have limited baffling (anyone have drawings for the LA-65??))

Prop wash does not cool the engine much -- most of the air is moving outside the circumference of the engine. The Service manual for the O-145 recommends ground ops not exceed 2 minutes in warm temps (!)

Here's an extract from the Lycoming O-145 Operations Manual:

GROUND RUNNING AND WARM-UP-- the LYCOMING 0-145-B2 engine is an air pressure cooled engine that depends on the forward speed of the airplane to maintain proper cooling. Therefore, particular care is necessary when operating this engine on the ground. To prevent overheating, it is recommended that the following precautions be followed:
Head airplane into the wind
Avoid prolonged idling at low RPM as this practice may result in fouled spark plugs
Limit ground running to 4 minutes in cold weather and to 2 minutes at temperatures above 70 F.

Here's some info taken from the Lycoming Flyer (http://www.lycoming.textron.com/support/tips-advice/key-reprints/pdfs/Key General.pdf):
B. ENGINE GROUND OPERATION
The engine ground operation greatly influences formation of lead salt deposits on spark plugs and exhaust valve stems. Proper operation of the engine on the ground (warm-up, landing, taxi and engine shut-down) can greatly reduce the deposition rate and deposit formation which cause spark plug fouling and exhaust valve sticking.
1. Proper adjustment of the idle speed (600 to 650 RPM) fuel mixture, and maintenance of the induction air system will ensure smooth engine operation and eliminate excessively rich fuel/air mixtures at idle speeds. This will minimize the separation of the nonvolatile components of the high-leaded aviation fuels greatly retarding the deposition rate.
2. The engine should be operated at engine speeds between 1000 and 1200 RPM after starting and during the initial warm-up period. Avoid prolonged closed-throttle idle engine speed operation (when possible). At engine speeds from 1000 to 1200 RPM, the spark plug core temperatures are hot enough to activate the lead scavenging agents contained in the fuel which retards the formation of the lead salt deposits on the spark plugs and exhaust valve stems. Avoid rapid engine speed changes after start-up, and use only the power settings required to taxi.
3. Rapid engine cooldown from low-power altitude changes, low-power landing approach and/or engine shut-down too soon after landing or ground runs should be avoided.
4. Prior to the engine shut-down, the engine speed should be maintained between 1000 and 1200 RPM until the operating temperatures have stabilized. At this time, the engine speed should be increased to approximately 1800 RPM for 15 to 20 seconds, then reduced to 1000 to 1200 RPM and shut down immediately using the mixture control.

Also:

Extended ground operation can cause excessive cylinder and oil temperatures.



More:

Preventing a buildup of contaminants is just as important as eliminating those that do form. Avoiding long periods of ground operation is a vital step since moisture can enter the breather, but will not vaporize when the oil is not heated to normal operating temperatures. Ground running also involves a slightly rich mixture which contributes to the formation of lead sludge in the oil. During flight, the deposit of lead sludge in the oil can be minimized by proper leaning.

[rosiejerryrosie]

Hi Dan - I do understand the idea of taping some cowl openings in the winter - I was playing devil's advocate (PC speak for being a wise a**) since your statement that the engine needed a lot of air movement for adequate cooling but that you taped openings so it would get appropriately warm. I am very glad that I did act like a wise guy because you did take the time to type the lycoming operating info - Great stuff! that I had never seen before. Particularly interested in to admonition to not run in excess of 2 minutes before takeoff. Do you really know anyone who does that? I would think that, in most cases, taxi time and runup would take more than 2 minutes. Anyway - interesting info and I intend to employ some if it (shut down procedures) and idle speed adjustments in the future. Makes a lot of sense. Thanks again for your time.

[MMontoya]

Ron,

Thanks for the reply. In the past I have done an oil change, put the battery on a digital trickle charger, and left it at that. While I haven't experienced problems in the spring, I don't know what unseen harm I have done. The one thing I know, is that I turn into a popsicle long in about 5 minutes airborne, so flying in the winter is not an option. I will look into the desicant plugs. I haven't used them before. One last thing; does the fuel system need special consideration for storage of 4 or 5 months?

Thanks,

Mike

[MMontoya]

Joe,

I had remembered a recent article this past year on the subject of oil that mentioned airplane storage. I will search again. Thanks.

[MMontoya]

Bill,

I keep the plane in Longmont. I have always tried to run the plane 45 minutes or more. The Christian inverted oil breather/drain line runs out the empannage. Water always come out at the end of an acrobatic flight, not always during upright flight. This water never has any oil in it. Do you think that the water is separated from the oil, and then drained out, or is it just the air in the breather being heated and then cooled further down the line causing condensation? PS - what do the Maroon Bells look like upside down?

[MMontoya]

Joe,

I am starting to see a consensus on the desicant plugs. I will look for the article on the dry air pump.

[DanChief]

No problem, Jerry!!

I've seen more than one big single sit on the runup area for 15 minutes at 1200-1500 RPM as the pilot tries to get it "warmed up."

One 210 owner I know did that every time. Then complains when he needs an OH at 500 hours... :(

The O-145 Ops manual also says the "airplane is suitably warmed up when the throttle can be advanced without stumbling."

That's my test. If it advances smoothly, it's time to take off! On cold days I can tell the engine runs more smoothly after a bit of flight time. It's "warmed up," but doing what it was designed to do -- fly!

[Bill Greenwood]

Mike, I was just in Longmont Sun buying some cheap gas. Unfortunately the lovely lunch lady had closed up the wagon for the winter season so I did not get a brat or burger, or a smile.
I get up to Longmont some and am at Boulder often, pehraps we could meet sometime, I'd like to see your plane.
I no longer have the Parakeet biplane, winter is real cold to fly it in Aspen so it went to west Texas.
The Bells look great anytime of year from any view!

[Bill Greenwood]

Dan, and you guys re winter opos.
There is a lot more to consider in starting a cold engine than spark plug fouling. I think you'd be nuts to start an engine in the winter that had been sitting outside and right away go to 1200 rpm, and double nuts to rev it to take off power after 2 minutes or as soon as it would take the throttle.
When an engine is cold soaked, there is a lot of metal friction that happens on startup until the oil warms up and circulates and the different rates of expansion between alum pistons and steel cylinders, etc warm up together.
Some experts think most wear occurs in the fiirst few minutes of each cold start.
Now you can and should preheat an engine in winter, but even that doesn't warm all the parts like being on a summer day.
As for overheating on the ground run, well you have oil temp and probably cyl temp gauges, when they are in the green it is time to go, not 2 minutes after a start at 20*, if it would even start that cold.

[DanChief]

Dan, and you guys re winter opos.
There is a lot more to consider in starting a cold engine than spark plug fouling. I think you'd be nuts to start an engine in the winter that had been sitting outside and right away go to 1200 rpm, and double nuts to rev it to take off power after 2 minutes or as soon as it would take the throttle.
When an engine is cold soaked, there is a lot of metal friction that happens on startup until the oil warms up and circulates and the different rates of expansion between alum pistons and steel cylinders, etc warm up together.
Some experts think most wear occurs in the fiirst few minutes of each cold start.
Now you can and should preheat an engine in winter, but even that doesn't warm all the parts like being on a summer day.
As for overheating on the ground run, well you have oil temp and probably cyl temp gauges, when they are in the green it is time to go, not 2 minutes after a start at 20*, if it would even start that cold.

well, let's define "Cold Weather Ops"

I used to live in Upstate NY -- below zero was normal and cold.

Now I'm in Pennsylvania, where 20 F is "cold."

So for me "Cold weather ops" is flying in temps between 20 and 35 degrees. I haven't flown my Chief in less than 20 F as it's just too cold in the cabin!

I usually preheat with a 100 W light bulb.

The taxi from my hangar to the runway takes me at least 5 minutes, so I'm usually ready for a run up. After that I'm in the green and the engine doesn't stumble when throttle is applied.

[MMontoya]

Diane close up for the winter week before last, . . . just in time for the snow. What airplane do you have now? Is it kept at Boulder?

[MMontoya]

Ron, I found a Lycoming Service Letter that recommends replacing the oil with an engine preservative if it is not going to be flown for more than thirty days. There procedure is to get this preservative oil to 180 F before shut down, and then to pull the plugs and fog the cylinders. Would this be the same if I just changed the oil with regular oil? In other words, change my oil, take one last flight to get it up to temp, and then pull the plugs and fog the cylinders. Spruce sells a kit with special spray gun to fog the cylinders.

[Bill Greenwood]

Mike, I mostly fly a Be 36 TC. I am based at Aspen, but fly into Boulder often for the weekends.
I have a Cub at Classic at Longmont being repaired after wind damage on tie down.

Re the special preservitive oil; I havent used it. It is probably a bit better on rust prevention than regular oil, but probably either would do well to preserve if sprayed in the cylinders.