Starting a plane in the cold

mandm

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Michael
I’m reading online that starting a plane in the cold can damage the engine. So a preheat basically is required? When traveling in the winter then I guess one must call a FBO to ensure they provide preheating services - what do they typically charge? Thoughts?
 
I’m reading online that starting a plane in the cold can damage the engine. So a preheat basically is required? When traveling in the winter then I guess one must call a FBO to ensure they provide preheating services - what do they typically charge? Thoughts?
If your plane has a built-in preheater, most will plug it in for free.
 
I'm in California, so I don't understand this whole concept of "cold". That said, I'm guessing that if the temp is low enough, the engine oil may be too thick to get pumped?

Tim
 
I'm in California, so I don't understand this whole concept of "cold". That said, I'm guessing that if the temp is low enough, the engine oil may be too thick to get pumped?

Tim

You’re in the wrong part of California. It was 23F this morning in Truckee, CA.
 
Starting an engine when it is cold can take some life out of it. It is best to plan ahead and stop at places that have services when you anticipate needing them. Frost and prolonged temperatures below freezing would be my primary concerns for overnight stops during winter months; I'd likely be stopping at places that can get the airplane inside a warm hangar or delay my departure long enough that the temperature warms enough to thaw the airplane out a bit.

You can have frost and cold enough weather for concern in much of the country this time of year. Don't assume that just because you're in a southern state that there will be no troubles.
 
Depends what your definition of cold is. Anything under 40F and I really like to plug it in. I’ve started sans preheat around 30F-ish before and it really didn’t like it very much. The biggest thing to keep in mind is that you want to get oil pressure as quickly as you can. When it’s cold, a lot of times the engine just doesn’t want to start very easily and you’ll spend many attempts trying to get it going. Once you do get it fired up, it will take longer to get oil pressure if you didn’t preheat than if you did. I started the Archer once without preheat and once it started I bet it took close to 10 seconds for the oil pressure gauge to come off the peg. It’s not a good feeling to see that propeller spinning and not having any oil pressure.

In short, preheat is your friend, especially on these expensive aircraft engines!
 
Yes, “pre-heating” services are a thing that an FBO can help with.
If you don’t have a plug in engine heater in the plane, some places may have a thingy that looks like a big hair dryer + hose that can be stuck into the engine compartment.
Or a heated hangar.
So yeah, it takes some calling/planning ahead.
 
Lycoming has an article / AC talking about cold weather ops. Also, as Ryan says, define cold. Up in ND nobly plugged in below 30 , so essentially anytime in Sep onwards till about May lol.

Look up that lycoming article. I am too lazy to find it right now…. A crap ton of Long Island ice tea might have something to do with it
 
People countless people start their cars cold every day during the winter, doesn’t seem to hurt them. I think if flying often I’d just fire it up without a care, if leaving it for weeks….that’s different.
 
Continental says with the proper oil the preheat threshold is 20°F. Lycoming says 10°. Even with proper oil the rotations are slow and the battery life is reduced. If convenient I preheat when temps drop below 30. If not convenient I’ll start in colder temps. Below about 15° a big Continental will frost the plugs almost as often as not.
 
You can ask the FBO if they can move your plane into a hangar if there's room or plan to leave a little later in the day after the sun has been on the plane. Except in really cold places, this should be enough to warn the airplane up.

Personally, if it's that cold, I don't want to do the preflight.
 
People countless people start their cars cold every day during the winter, doesn’t seem to hurt them.

What people do with their cars has little in common with old aircraft engines.

The old guy who ran the first maintenance shop I worked in always said that the worst thing that happened to aircraft engines was the introduction of multi viscosity oils. Prior to multi viscosity oil being available, when it was too cold for an engine to start without preheat it just wouldn't start. After multi viscosity oil became available engines got easy enough to start that people got complacent with preheat. The longer I'm around these engines, the more I think he was at least partially correct.

Assuming the OP is referring to the same aircraft that has had major engine work recently completed which is being asked about in another thread, the chances of me starting a cold soaked engine is about zero regardless of what oil is in the engine.
 
I’m reading online that starting a plane in the cold can damage the engine. So a preheat basically is required? When traveling in the winter then I guess one must call a FBO to ensure they provide preheating services - what do they typically charge? Thoughts?

The problem with airport forced air preheat is it takes forever to warm the oil and crank shaft.
 
Frost forming on and grounding out spark plug during compression during cranking the engine.
The frost comes from the water vapor created when the first firings take place. It's not a product of compression. Few people seem to get the point that burning fossil fuels creates vast amounts of water. Fossil fuels are full of hydrogen that combines with oxygen from the air to form that water. A gallon of gasoline will create nearly a gallon and a half of water.

I had an old International Farmall Cub. I used it for clearing snow out of the driveway. If I didn't preheat that engine in cold weather (like -20°C), it would fire for a second and then quit. Pull the plugs out and they had frost on them. If one stuck a borescope in the cylinder it would be all a-glitter with frost in there.
 
What people do with their cars has little in common with old aircraft engines.

The old guy who ran the first maintenance shop I worked in always said that the worst thing that happened to aircraft engines was the introduction of multi viscosity oils. Prior to multi viscosity oil being available, when it was too cold for an engine to start without preheat it just wouldn't start. After multi viscosity oil became available engines got easy enough to start that people got complacent with preheat. The longer I'm around these engines, the more I think he was at least partially correct.

Assuming the OP is referring to the same aircraft that has had major engine work recently completed which is being asked about in another thread, the chances of me starting a cold soaked engine is about zero regardless of what oil is in the engine.
Exactly. Cars, once again, are not airplanes.

That aircraft engine, being aircooled, runs at much higher temperatures than your car. Therefore, it has larger clearances to avoid seizure when cold aluminum pistons warm up in still-cool steel cylinders. Aluminum expands at twice the rate of iron or steel. And since those clearances are large and the engine gets quite hot, and since any mineral oil decreases in viscosity as it warms, It has to start out thicker than the oil in your car. A common multigrade aircraft engine oil is 15W50 or 20W50, while a common automotive multigrade is 5W20. When it's at -10°F (+14°F) there's a big difference in viscosities between those two oils. Furthermore, the oil pump in an aircraft engine is well above the level of the oil in the sump, and it has to suck that thick oil up the pickup tube. Think McDonald's milkshake. It doesn't move too fast. So the engine doesn't get much oil, and those bearings resent that. In your car, that engine has to spin the flywheel and the alternator and so on. In the airplane, that engine is already having to spin that propeller, a much, much larger load than your car's engine sees right after startup. Those bearings are carrying significant loads already, and getting no lubrication, so they start burning up. Isn't that nice? No, it's not the same as your car.

In the Aircraft Systems course I used to teach in college, one of the classes covered lubrication. The night before I would take quarts of W80, W100, and 15W50 and stick them in the freezer in the fridge. Get them down to maybe -10°C. Just before the class I would take more quarts of those same oils and immerse them in a tub of water on the stove and heat them until the water boiled and hold it there for 15 minutes or so. In the class I would take room-temp quarts of the same oils and do a pouring demonstration onto a sloped ramp. They'd see what they saw when they topped up the oil in the airplane. Then I'd take the frozen oils and do that pour demonstration, and the difference was absolutely stark. The W100 would barely move. W80 was a bit better. The 15W50 flowed not too bad, since it's near an SAE15 oil at that temp (same viscosity at -20) but you still wouldn't want to have to suck it up any tube. Then the heated oils: W100 flowed, W80 flowed faster, and 15W50 flowed about like W100, of course, since at that temp is has the same viscosity as W100, which is an SAE50 oil.

This chart is for a diesel engine 15W540 oil, but the principles of aircraft multigrades is the same:

upload_2021-12-21_19-9-10.png


This subject comes up every year when the weather turns cold. Every year. The forum archives are full of it.
 
Thanks for the great replies. How long would you plug in a pre-heater for? (Engine preheater plug)
 
Thanks for the great replies. How long would you plug in a pre-heater for? (Engine preheater plug)
At least 2 hours….takes time for heat to warmup a very large chunk of metal. I have a remote switch, and turn on the heater the evening before I fly.
 
The frost comes from the water vapor created when the first firings take place. It's not a product of compression. Few people seem to get the point that burning fossil fuels creates vast amounts of water. Fossil fuels are full of hydrogen that combines with oxygen from the air to form that water. A gallon of gasoline will create nearly a gallon and a half of water.

I had an old International Farmall Cub. I used it for clearing snow out of the driveway. If I didn't preheat that engine in cold weather (like -20°C), it would fire for a second and then quit. Pull the plugs out and they had frost on them. If one stuck a borescope in the cylinder it would be all a-glitter with frost in there.

What stroke does the plug fire on?
 
Thanks for the great replies. How long would you plug in a pre-heater for? (Engine preheater plug)

That depends on the engine, the temperature, the heat system, and whether you have an engine cover.

In any case it does take time to heat an engine and 8-10 qts of oil.
 
When I read cold, I assume it meant below freezing.
Not below 10°F! Forget flying, I wouldn’t leave the house to get to the mailbox.
 
What stroke does the plug fire on?
If you want to be technical? Frosting the plugs happens during the power stroke and subsequently the intake stroke. The way it happens is you prime a cold-soaked engine. For guys not familiar with it cold engines require a lot more prime than normal. In an effort not to flood it we tend to under prime it. It fires on a few cylinders but doesn’t catch. If the cylinders are cold enough there’s a good chance your plugs are now frosted and the only way to get it to start now is a good preheat to get the cylinders warm.
 
Thanks for the great replies. How long would you plug in a pre-heater for? (Engine preheater plug)

Again depends on the preheated that’s installed, only on the oil sump? Around cylinders? Both? I have reif turbo XP. Min 2 hours to get the temps up. Night before is best and again depends on the temp outside and if you have a cone cover on (highly recommended). If you have the right setup, getting the oil to 110 and cylinder heads to 150 or more is doable even in -23f - that’s the lowest I have flown.
 
Here's where a hangar can be really important. I have a little heater thingie, it cost me some coin, but less than an installed system. I stick it in the nose cowling and add plugs. It has a thermostat and keeps the engine bay at 75 degrees all winter. Airplane is ready to start when I am.
 
When I taught in Ohio, the school had a rule that no solo flights were permitted below 20? Maybe 10? degrees F, and no dual flights below 10 or 5 degrees. When I started there I thought that was crazy - but sure enough, the first winter, I often flew at those temperatures.

That school kept its planes outside (unless you specifically asked the day before to have it put in the hangar for a morning flight), and did not preheat at all. So not a great data point - but they were flying those airplanes a lot.
 
My flight school didn’t let solo flight under zero in ND. Not because the plane couldn’t, but in case the student had do a forced landing, there is a high chance he/she would freeze to death in some cornfield
 
People countless people start their cars cold every day during the winter, doesn’t seem to hurt them. I think if flying often I’d just fire it up without a care, if leaving it for weeks….that’s different.

Yes this is how I feel about it. Anything above 0* F I just make sure to let the engine warm up a bit before I ask for a bunch of power out of it. Below 0* F I guess I'd have to borrow a heater from someone.

How do the heaters work anyways? Are they just blankets over the engine or something?
 
My flight school didn’t let solo flight under zero in ND. Not because the plane couldn’t, but in case the student had do a forced landing, there is a high chance he/she would freeze to death in some cornfield

Use the avgas in the plane to create a fire. Or burn down the plane and say it happened during the landing. Now you don't have to tow the plane out of a field.
 
When I taught in Ohio, the school had a rule that no solo flights were permitted below 20? Maybe 10? degrees F, and no dual flights below 10 or 5 degrees. When I started there I thought that was crazy - but sure enough, the first winter, I often flew at those temperatures.

That school kept its planes outside (unless you specifically asked the day before to have it put in the hangar for a morning flight), and did not preheat at all. So not a great data point - but they were flying those airplanes a lot.

When I was flight training it seemed like it was either 95+°f or 10°! When it was hot out the plane didn't want to start and we had had to wait 2 minutes for the starter to cool off. How is it going to cool off when it is 95 out! Meanwhile you are dying in the heat in the cabin.

When it was cold out they would send me out on the ramp with a hairdryer and we would place it in the cowl with the cowl plugs in. I would go back in the building the flight instructor would say "you ready?" I would say yup and out we would go and the hairdryer would run maybe 5 minutes, more than once! The flight school runs the motors to 3000 hrs before overhaul.

The school would not want you to fly their planes when it was under 10° f. Several times when I was renting planes I would get there and it was 5°. They said go ahead it will be 10° when you get back and the owner won't get here until later. LOL

My plane sits in a unheated hanger, I plug in the heat pad that is on the sump about an hour before flight. Sometimes I still stick a old hairdryer I have in the cowl and leave it run for a while. Old habit from the flight school. I also have a couple portable gas heaters I can blast the plane with on real cold days before I open the hangar door to warm up the inside of the plane.
 
Thanks for the great replies. How long would you plug in a pre-heater for? (Engine preheater plug)

When the oil drips off the dipstick, it is warm enough to start.

When I worked in Alaska we had engine covers and electric tanis heaters attached to the engine, which we plugged in after every flight. In the morning the engine(s) would be near operating temps and starting was same as summer.

In New Mexico we used electric heater sticks that are used to start charcoal that we laid on top of the engines. All we had for engine covers was a piece of carpet turned upside down.
 
When the oil drips off the dipstick, it is warm enough to start.
On the Canadian prairies we had to preheat the engine before we could pull the dipstick out. That oil was so thick the stick was glued in there. We couldn't talk outside, either, since your words would freeze and fall to the ground. Had to go inside to chat. Had to keep the fire in the stove really hot, too, or the smoke would freeze in the chimney and back it up into the shack. Had to up on the roof with a long stick and bust the smoke loose.

:)
 
Yes this is how I feel about it. Anything above 0* F I just make sure to let the engine warm up a bit before I ask for a bunch of power out of it. Below 0* F I guess I'd have to borrow a heater from someone.

How do the heaters work anyways? Are they just blankets over the engine or something?

I used to have one on my engine, it was a heating pad glued to the oil pan.
 
Yes this is how I feel about it. Anything above 0* F I just make sure to let the engine warm up a bit before I ask for a bunch of power out of it. Below 0* F I guess I'd have to borrow a heater from someone.
Good way to ruin your engine. Even 15W50 is thicker at that temperature and won't pump easily to the bearings. Sooner or later metal will show up in the oil screen or filter.

Oil that cold has been known to rupture oil coolers, too, if the the engine's relief valve is at the end of the system.

Cars are NOT airplanes. Too many owners have found that out the hard way.
 
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