Time to cool engine <40degs, after landing

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SSR

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SSR
I've tried to find some data or research on this, with no luck. I usually guess, but I'm still breaking in a new top end and want to be more confident.

It will be very cold this coming weekend. At my home field, the plane is inside a hangar, with Tanis heaters on each engine. My destination will not have any way to protect, plug in or pre-heat the plane. I only need to be on the ground for an hour or two, but it will be 10-15 degrees F and blowing in the teens. Is there any data to know if the engine will cool, from full operating temperature to below 40 degrees in that short of a frigid window? The most I can do to retain heat, is put the cowl plugs in.
 
I can only offer anecdotes, but I've been on the ramp for a couple hours in those conditions with cowl plugs in, and the oil is still up in the 80's. Cowl plugs make a huge difference.
 
which engine? I guess I'm asking how large it is. An IO-540 will retain more heat than a significantly smaller 4-banger.

I'm going to guess non-Turbo?
 
I think cowl plugs, sponges for most of the other various openings in the cowl (don’t forget to remove them all when ready to start up), and blankets. If really worried, use some kind of tenting material to get the cowl out of the wind also, and use gun socks on the prop blades. Put everything on asap before you actually tie down to prevent further heat loss.
 
Engines are IO-550s.

I use cargo blankets in my hangar, which do a remarkable job of allowing the tanis heaters to heat soak the entire nacelle. They would not remain in place on the windy ramp and I'm not going to have time, before the weekend, to fashion any sort of tie downs. In addition to the cowl plugs, I have a plug for the top air scoop intake.

The prop really is a heat sink and will freeze quickly. It's the jugs and oil that I'm most worried about.
 
You probably won't have time to make a couple of these, but they work well to heat the engine in any remote area without power. It's a propane camping stove inside a tomato trellis connected to the cowling with a dryer hose. It's inexpensive and light weight.


heaterframe.jpg heaterframe2.jpg
 
Maybe have the oil level a bit higher so you have more oil mass that has cool, but 2 ours you will be fine.
 
With cowl plugs to limit air flowing through the cowl you should be fine for a few hours. Continental says cold soaked below 20°. I’d expect your oil to still be warm and that’ll contribute heat to the cylinders. My reply comes from lots of days ice fishing. I never needed to preheat to get home.
 
It will be fine. I’ve gone 4+ hours between flights and the oil temp is still 75f+. Granted, the OAT’s haven’t been as cold as what you’re operating in, but still, a couple hours with cowl plugs? Don’t sweat it!
 
As purely anecdotal information, last week it was sunny but 30 degrees with 10 MPH winds for our breakfast run (Bellanca with an IO-470). Oil temp was around 100 and cylinders were still warm to the touch at startup after 1.5-2 hours. That was without cowl plugs or covers of any kind. 500 lbs of metal at 300+ degrees takes a while to cool down.
 
It's a little messy, but there is also Alaska legend Don Sheldon's technique of draining the oil and keeping it warm inside - as long as you're sure to replace it before start up. :)
 
dbahn said:
It's a little messy, but there is also Alaska legend Don Sheldon's technique of draining the oil and keeping it warm inside - as long as you're sure to replace it before start up. :)
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If you are going to do that, I assume you also bring the battery inside?
 
As a life-long Alaskan immersed in GA, I’ve never heard of anyone doing the drain oil-take inside thing. In above zero temps any healthy battery should work fine. If it gets cold enough that you’re concerned about cranking speed? Rotate the prop(s) by hand a few times to scrape the frost off the cylinder walls. The engine will spin easier.
 
Some interesting ideas above that I will not have time to adopt, unfortunately.

Despite the manufacturers 20 deg threshold being different from the best practice of 40 deg pre-heat, this is a very important issue for piston engines. I'm surprised a study hasn't been done to test the cool down periods, from normal operating temperatures.

My best guess is I'll be fine. As I stated, I'm only about 5 hour into a top end break-in and documentation says it's even a more critical issue, at this stage. Wish I didn't have to guess. With just opinion to go on, including my own, I'll probably try to limit my layover, as much as possible.
 
Mongoose Aviator said:
If you are going to do that, I assume you also bring the battery inside?
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Actually, a fully charged battery in good condition does not need to be kept warm. (They seem sluggish in cold weather but it's typically due to the engine and oil being cold.)
 
SSR said:
Some interesting ideas above that I will not have time to adopt, unfortunately.

Despite the manufacturers 20 deg threshold being different from the best practice of 40 deg pre-heat, this is a very important issue for piston engines. I'm surprised a study hasn't been done to test the cool down periods, from normal operating temperatures.

My best guess is I'll be fine. As I stated, I'm only about 5 hour into a top end break-in and documentation says it's even a more critical issue, at this stage. Wish I didn't have to guess. With just opinion to go on, including my own, I'll probably try to limit my layover, as much as possible.
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Who says 40° is best practice? What data is there to support it? Do you get additional warranty or TBO for doing it?
 
Stewartb said:
Who says 40° is best practice?
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I suppose the colloquial word 'best' is a misnomer, given the controversy over the entire topic. I think 40 degs is the most commonly used threshold, among so many varied opinions. Not unlike Mike Busch recommends keeping CHT below 380, when the OEMs set a much higher red line. Perhaps the OEMs are okay with more rapid wear, for obvious motivations.
 
p.s. Having just done a top end about half way to TBO, I'm good with being a bit more prudent. Crap TCM cylinders will never live on my engine ever again. I've never gotten TBO out of all of them and I take good care of operating temps. I only needed a couple done, but I've seen this play before. One or two every year, until I end up doing them all and repeating the R&R labor. Just got it over with.
 
SSR said:
Engines are IO-550s.

I use cargo blankets in my hangar, which do a remarkable job of allowing the tanis heaters to heat soak the entire nacelle. They would not remain in place on the windy ramp and I'm not going to have time, before the weekend, to fashion any sort of tie downs. In addition to the cowl plugs, I have a plug for the top air scoop intake.

The prop really is a heat sink and will freeze quickly. It's the jugs and oil that I'm most worried about.
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If using blankets in the wind, ever hear of bungee cords? They will work well but be ever careful to avoid the elastic recoil hitting your face or eyes- very dangerous.

The prop is a heat sink; that is why one should cover the blades with gun socks to prevent it sucking the heat out of the engine at an accelerated rate.
 
You'll be fine with engines that large. They'll hold heat for a long time. Cowl plugs will help.
 
Can you duck out of whatever you're doing to restart the engines and run them long enough to warm them back up? Or maybe hire a mechanic to do it? While that's not ordinarily a good tactic it shouldn't be a problem if you're running them normally an hour or two later.
 
nrpetersen said:
Park facing downwind too.
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That's a good idea and the line crew rarely come out to marshal this time of year. They always try to park transients into the wind, which is most often preferred. Current conditions are forecast to be about 10F with winds 11G18. If they'll just clock a bit more to the west and the ramp is empty, there is a place I could sneak behind a building to block the wind. Wind chill will be -3F. On the other hand, after mid day, it will also be in the shade. I don't think a white nacelle absorbs much solar heat anyway, so I'll take getting out of the wind, if I can.

I think I can keep my downtime to about an hour. I'm feeling better about my chances for that short a period of time.
 
Clip4 said:
Maybe have the oil level a bit higher so you have more oil mass that has cool, but 2 ours you will be fine.
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The engines weigh 500 pounds apiece. Adding an extra quart or two of oil isn't going to add enough mass to the overall assembly to matter.

If the OP inserts cowl plugs, the engines will stay fairly warm for a couple of hours.
 
Stewartb said:
As a life-long Alaskan immersed in GA, I’ve never heard of anyone doing the drain oil-take inside thing. In above zero temps any healthy battery should work fine. If it gets cold enough that you’re concerned about cranking speed? Rotate the prop(s) by hand a few times to scrape the frost off the cylinder walls. The engine will spin easier.
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What?
Scrape FROST off the cylinder walls so the engine turns over easier??
 
Don't park into the wind. Cowl plugs work well.

If this is something you do regularly, consider getting a customized warming blanket. I have one from Tanis for the Bonanza. It's amazing how well it keeps the engine compartment warm, even on a windy day.

- Martin
 
Stewartb said:
As a life-long Alaskan immersed in GA, I’ve never heard of anyone doing the drain oil-take inside thing.
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I hope that doesn't mean that you've never read Wager With the Wind, a fantastic recounting of Don Sheldon and his career as a bush pilot flying climbers to Mount McKinley from the now small strip in Talkeetna.

If you haven't read it, it's never too late. :)
 
I’ve read it. His widow was a customer and one of my favorite people. His son and his partners are also customers. I do love that book.
 
Somewhere in there he describes how he drains the oil and brings it inside overnight.

A few years ago I met one of his relatives in Talkeetna. She was a waitress and essentially sat down at our table to chat.
 
Old Alaskan pilot story. Nobody does it or has done it since multi-vis oil and decent preheaters were invented, which pre-dates me. I’ve pre-heated in -40°. It takes time. No way pouring 6 quarts of oil into 300# of -40° steel makes any impact worth the exercise.
 
Cowl plugs. I fly Cirrus sr-22, last year I flew to PQI Presque Isle Maine. It was about 20 in Massachusetts, get there and it was -10 F. I had dropped off passengers (Angel flight) then pulled over to the new pump to fill up. The pump was frozen, wouldn't work. Long story short after about an hour and a half of the line guy futzing thinking he could get it working, he gave up. I had enough gas to get where I needed to go, so I pulled the cowl plugs out, fired up the avionics, the oil temp was still at 120. The engine fired right up.

Before that I was at Nantucket, 20 degree day, about 4 hours. Pulled the cowl plugs out, engine oil temp was 80 degrees. One caveat is that the Cirrus is composite which insulates better than aluminum.
 
I'll report back after the flight today. Oil temp is probably indicative and suggests it will flow, but itself isn't my concern. It's CHT, which I think needs to be above 40 to be comfortable during break-in.

By the way, I'm not sure there is any winning on which direction to face. The cowl flaps say open a crack in the back, which would probably funnel air into the nacelle.
 
Did not see this coming. 1 degree in hangar. It was well below zero all evening. The gas powered tug would not start. I'm sure I could warm it, with a space heat, to get it started, but it's too late to lap back. Maybe it was engine gods keeping me from trying this. Thanks all for the thoughts. I did learn, by the way, there are pretty clear physics formulas for "heat capacity", which is the amount of energy required to change the temperature of an object. I just had no idea what inputs to use for the plane.
 
Stewartb said:
If it gets cold enough that you’re concerned about cranking speed? Rotate the prop(s) by hand a few times to scrape the frost off the cylinder walls. The engine will spin easier.
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:D
 
Not the intended scenario, but may be of some interest. When I landed (the next day), it was 39F outside temp, with 15G25 wind. I was shut down for 1hr and 11 minutes, before restart. CHTs were between 110F-120F, at restart. Obviously, not the scenario I was concerned about, but I thought they cooled off far more than I would have expected.
 
Wow with cowl plugs? That surprises me. Maybe the 'glass cowl makes a bigger difference than I thought. I got it in my head you're talking about a baron? I'm assuming it has aluminum cowls?
 
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