Winter operations / lowest temperature for starting / preheating methods (merged)

Jacko wrote:

Integrating differential equations based on Newton’s law of cooling looks great fun, but an engine monitor with OAT, CHT and oil temp might provide the means to check the result empirically.

Peter.

Would just require Peter to sleep in his plane overnight. You could then compare the temperature decay of a TB20 with a person.

what_next wrote:

Sorry to be nitpicking here (had to study lots of thermodynamics in a previous life) but “radiation cooling” is absolutely no factor here, especially with regards to the propeller. In order to be dissipated through the propeller, the heat of the engine must first be conducted through the propeller shaft (made of iron, a rather poor conductor for heat) and hub to the blades.

Ok I concede to your knowledge of thermodynamics and the proper use of its terms. So change radiates to conducts to cause temperature change. The prop acts like a heat sink so that the Tanis or Reiff systems heat up the engine with less efficiency and may never reach the temp it would have if an insulated prop cover is used.

Here is what Reiff wrote:

“PROP & SPINNER COVERS: These are made from the same material and thread as the engine covers, and serve two purposes. First, they help prevent loss of heat through the aluminum blades and prop hub, which can be substantial. Think of your prop blades as huge cooling fins. A customer has run tests and reports that the temperature of his preheated engine is 10o F warmer with prop and spinner covers than without. Second, without insulating your prop blades and hub the front main bearing probably will not be as warm as the rest of the engine, making it more susceptible to wear and damage from cold starting.”

Now to add some informative information to this thread:

www.kennoncovers.com/enginecovers.html
New one about front main bearing being frozen even with the plane plugged to Tanis due to cold conduction

http://www.reiffpreheat.com/Article-Sutton.pdf
Great article about dehydrating as well as using engine covers. Now before you statisticians comment that the information is not statistically relevant or accurate due to sample size just be happy someone took the time out to try and do a somewhat scientific study.

http://www.oilcoolers.com/article_oil_cooler_woes.asp
Another thing not mentioned by any of the respondents here was oil cooler damage. Especially if you use straight wt. So heating the oil will do no good actually may cause engine failure if taking off in 0 deg F temps.

http://www.gridwatch.templar.co.uk/

C210_Flyer wrote:

http://www.reiffpreheat.com/Article-Sutton.pdf
Great article about dehydrating as well as using engine covers. Now before you statisticians comment that the information is not statistically relevant or accurate due to sample size just be happy someone took the time out to try and do a somewhat scientific study.

This is really an amazing article, many thanks for posting it. The Cessna twin flyer supports all efforts in an impressive manner I use to protect my engine, as preheating, engine dehydrating and Camguard. I did understand he use preheating every time? I have learned from Mr. Deakin that preheating is necessary when temperatures drop below 40° F, which is about 4°C.
By the way I use blankets in the hangar for all upper surfaces of my aircraft all the year to protect from birds shit and dirt.

highflyer wrote:

I have learned from Mr. Deakin that preheating is necessary when temperatures drop below 40° F, which is about 4°C.

Necessary? I don’t really know… I have been flying piston twins since 1991 or so, sometimes more, sometimes less in cental European climates. None of them ever saw a hangar from the inside. During all that time, I had to preheat exactly one time: On an overnight stay in Goose Bay at -35…-40°C. We arrived too late at night to put the aircraft into a german airforce hangar (which we had arranged in advance) so it had to stay outside. In the morning, there were oil crystals on the dipstick and it was impossible to turn the propeller by hand. But apart from that one time there was no need to preheat.

what_next wrote:

But apart from that one time there was no need to preheat.

I think the word __pre__heating is wrong and misleading. You can be led to believe that all you “have” to do is to heat the engine before starting it. That is only half the reason for heating the engine. Either you keep the aircraft in a heated hangar, or keep the heater on 24/4. By keeping the engine above ambient temperature, if ever so little, one degree is enough, no condensation will occur. More heat, and trapped water will evaporate faster. No condensation, no corrosion. If you run the engine every day, it’s no big deal of course, heating just prior to flying is enough. You have to fly for at least an hour though. But if the engine is left for longer periods, it should be heated. In the right condition (or wrong, depending on how you look at it), water will accumulate inside the engine. There was a CAP-10 who had a complete loss of oil in flight, due to accumulation of water, the water froze and blocked the oil lines. This typically also happens to cars that are run only 10-20 minutes each time in subzero conditions, and with no heater.

Peter wrote:

I hope he is wrong, otherwise I am wasting my time putting in a new engine this winter

https://www.advancedpilot.com/downloads/prep.pdf: page 20
“NEVER start a recip with the oil temperature below about 40°F.”
Who is wrong?
what_next wrote:

I had to preheat exactly one time: On an overnight stay in Goose Bay at -35…-40°C.

I admit that I am less experianced than you. Different statements from Lycoming, Cessna Twin Flyer, John Deakin and from you leaves some uncertainty.