Engine preheat

[IO540]

Some Lyco engine recommendations suggest preheating if the ground OAT is below +6C.

Yet it is obvious that almost nobody in the UK does this, and indeed most cannot. Even most hangared owners are not allowed to use mains electricity in the hangar.

Is this a real risk?

The damage in the first few seconds of engine running must be almost totally related to the oil used. And I wonder if this is a fossil recommendation from the pre-multigrade days?

[wsmempson]

I reckon the recommendation is to do with differing rates of thermal expansion between the various metals in the engine. Certainly the 6 cylinder DB4/5&6 Aston engines needed preheating if the ambient temperature was sufficiently low, as the alloy block would contract faster than the steel crankshaft and 'grip' the crank.

Of course, once the engine was sufficiently clapped out and the tollerances were loose enough, the problem would go away (or be substituted for an entirely different problem).

[S-Works]

I seem to recall that F1 engines are actually seized when they are cold which is why the have to be pre heated.

[Pilot DAR]

Only in the most dire of "gotta go right now" circumstances would I not preheat my engine. I like to see at least 50F oil temperature before I start in the winter.

That said, I NEVER put multi grade oil in my engine, I have had terrible experiences with it. So it's only fair to get the 80 grade oil to the temperature it should be, before demading it lubricate freely...

Yes, when I worked at the engine shop, we did see damage which we attributed to very cold starts, and no lubrication at the beginning. You know how it takes longer for oil pressure to indicate in the cold? It's taking the same longer for that cold oil to work under pressure, where you most need it to lubricate effectively!

[Jan Olieslagers]

Can't help mentioning the story - more or less on topic - of the high-gloss Italian car of the interbellum, that was supplied complete with, among many other accessories, two large copper tubs. In preparation for a winter ride, the owner/driver was supposed to drain the radiator in one, the oil carter in the other, and leave both basins on the kitchen stove overnight. Restoring their contents to their normal residence would ensure proper engine temperature for starting.

Must have been a Lamborghini, if it wasn't a Bugatti.

[cjboy]

Only in the most dire of "gotta go right now" circumstances would I not preheat my engine. I like to see at least 50F oil temperature before I start in the winter.


In Canada you are well organised enough to be able to do this; with the weather so cold in a "normal" Canadian winter it's good to see a country that gears itself up to deal with whatever nature throws at you all. I wish that the UK was so prepared.

I understand that in Canada it is not unusual for cars to be "plugged in" at night to enable electric heaters to keep their engines at a sensible temperature.

[Silvaire1]

The Canadian guys are best placed to answer this but I don't think it's a huge area for concern with relatively mild UK temperatures, and particularly with multi-grade oil, if used.

I can remember starting O-200s with a squirt of ether, because they simply would not start on avgas due to low ambient temperature. No hangar was available. Ether's risky if used in excess but I don't think the bottom end suffered.

The biggest issue with startup lubrication in my mind isn't cold weather - it's loss of oil pump prime with some engines (Continentals especially) if they're unflown for a period... And the attempts to start them before prime is re-established.

Whatever Lycoming suggests, don't let those knuckle heads at EASA find out! :oh: :ugh:

[IO540]

Aren't there heating devices which go into the oil dipstick hole?

[sycamore]

You can buy a car pre-heater that plugs into the cigarette lighter outlet,but maybe the wiring may not take prolonged use.Otherwise,use a spare battery,and jump leads to the plug.Would also be better to drain the oil and heat it prior to going to the airfield......A little `bush-craft`....

[POBJOY]

Hi There PD
I would be interested in (what your problem is with "multi grade" oil)
Preheating in the UK in nearly unheard of (and so is dilution with fuel)
As the resulting "Carb fires" are usually an insurance job i assume no one gets excited re the situation.
I did my own tests and "switched " to a 15-50 (well known make) that sounds like bell.
I noticed at least two advantages :-
Much better starts in cold weather and pressure comes up quickly.
Much better exhaust valve lubrication during normal use.
If it is really cold (as we have experienced of late) i blank of the air intakes and give it half an hour with a fan heater.
The difference is amazing, it starts on the button (if it had a button) the pressure comes up and it runs smooth at once without having to do more priming or Throttle pumps.
AS for using multi grade in "hot" weather i have to say that my T&P's are always L&H in that order and one can always "top up" with mono grade between changes.
As the Machine gets used for "Towing" the tests were for real.
I found that there was a difference between the 20w50 and the 15-50 so stuck with the latter.
THis is with a Lyc 4 potter (180hp) that needs hardly any top ups and keeps its comp's up.
I am not suggesting that this oil would be suitable for a large radial with reduction gears but would not dismiss trying it out.

[CanAmdelta1]

Silvaire1

I agree, I don't believe infrequent use of starting fluid is that harmful and prudent use as you mentioned is on target.

Just keep in mind it can contain as much as 60% dimethyl ether and most 4 strokes can't handle extreme pressures on ignition, especially cold. It also has no lubricating properties. Great used on high compression engines such as diesels however.

If you can wrap the cowl and preheat engine compartment while you get a coffee and do a preflight.....the engine should start with carb heat on by using the warmed air inside cowling to atomize the avgas.

Also I believe multigrade oils work well, however even if one drains the oil after flight and brings it into the camp in order to keep it warm, it does nothing for the differences in the engine metallurgy properties the next morning at startup.

As a fellow Canuk mentioned only a most dire situation on the ground would cause me to deal with a possible most dire problem in the air.

[SNS3Guppy]

The damage in the first few seconds of engine running must be almost totally related to the oil used. And I wonder if this is a fossil recommendation from the pre-multigrade days?

Wear and damage are different animals. Wear during initial engine start is always an important consideration, but if you're not using a pre-oiler, you're not giving it consideration anyway, temperature not withstanding.

Preheating is not a "fossil recommendation." If you care about your aircraft, it should be mandatory. Anytime you're below about 40 degrees F, you should be preheating.

Preheating isn't just about keeping the oil flowing. The entire engine should be preheated, not just the oil.

Aren't there heating devices which go into the oil dipstick hole?

Dipstick heaters tend to be too hot, and can damage the oil. Oil heaters that span the bottom of the sump are also available, but still do nothing to heat the engine; just the oil Tannis sytems that encircle each cylinder and warm the engine and the oil are much better, and should be used with a shroud or blanket that covers the engine nacelle to retain the heat.

The poor boy engine heater is a work trouble light laying on top of the cylinders, with a blanket over the engine.

Combustion space heaters with a hose to the engine compartment also work well, but it's far better to have the engine stay preheated all the time, rather than start heating the engine before the flight.

A "fossil system" is oil dilution, which was factory-installed in some aircraft, standard in some, optional in others. It involved running avgas into the oil prior to engine shutdown, in order to reduce oil viscosity. In theory, the avgas would vaporize and allow the oil to return to it's original state after the next engine start.

Dilution changes oil chemistry, leaves deposits, and adds a solvent to a lubricant: never a good solution. Nearly all oil dilution systems have been removed or deactivated today.

Removing oil from the engine and keeping it warm, then returning it to the engine is a necessity when temperatures will drop enough to congeal oil. This still doesn't heat the engine throughout.

The engine is made up of various metals, each of which have different expansion rates. The entire engine should be heated uniformly, as best able, prior to engine start, for cold weather starts. Adding heated oil to the engine doesn't accomplish this, but does at least get oil flowing during the initial start, which is better than not having the oil flowing.

[POBJOY]

Interesting thread this, but it got me thinking how my old VW 1200 (1955) Beetle engine never needed any special treatment to go to work every day.
On some days the car would look like an huge snow drift and you may have to "heat" the key to unlock it but as long as it "cranked" (6 Volt remember) it went and the oil light would go off in a second.
Now this engine was very similar in construction to what i fly behind today.
Steel crank,Allui or Mag alui crank-case,steel cylinders,Steel rods,Allui pistons,allui heads with alloy bronze guides and normal valves,operated by steel camshaft and followers.
In those days (mid sixties) you had the option "like today" of mono grades Castrol 20 30 40 XL20-50 or the "new" Castrolite" (which i used).
The hand book suggested various grades depending on the average OAT but in the UK the 30 or 40 would have been normal.
That engine did over 150,000 miles before a teardown to replace a fibre cam drive that got oil soaked and failed. (a known problem)
Years later i did hundreds of hours behind all sizes of VW engines that did not know they were flying (nor did they care).
The question is was the VW just a very good engine that could run in the Artic or the Desert or was it having the correct lubriction for the application that made the difference !!!

[IO540]

Two main things have changed in aero engines lately: multigrade oils (which are not so viscous at low temps) and most "advanced" owners have the "Skytec"-type high speed starter motors which crank the engine 2x to 3x faster than the old style starters.

In the UK, largely due to airfield/hangarage politics, almost nobody has the facilities to preheat engines.

Yet there is no evidence that UK based engines are getting trashed at great rates. I send my oil analysis to a US lab and my metal numbers are in line with the US averages.

What I do see regularly is people unable to start their engines. This is probably a combination of using straight oil, knackered batteries, and knackered starter motors. But that is a separate issue to doing damage to the engine by starting it at say 0C without a preheat.

[SNS3Guppy]

Lately is a relative term, apparently. Multi-grade oils have been in use for several decades now, and offer significant advantages over single-grade oil.

n the UK, largely due to airfield/hangarage politics, almost nobody has the facilities to preheat engines.

One needn't have a hangar to preheat an engine.

Yet there is no evidence that UK based engines are getting trashed at great rates. I send my oil analysis to a US lab and my metal numbers are in line with the US averages.

The spot numbers for your spectrometric oil analysis aren't nearly so important as the trends.

"Getting trashed" or not isn't really the issue. There's no question that preheating reduces the amount of warm-up time required, and that it does reduce wear, every bit as much as preoiling reduces wear. Whether your engine gets "trashed" or not is another matter.

I'll have to add this to the list of "UK Uniqueness," though. Carburetor heat, mixtures, low altitude flight, and apparently cold weather operation all work differently within the geopolitical borders of the UK...an apparent conundrum in the aviation world from which the remainder of the globe could apparently learn aplenty.

The rest of the thinking world uses any number of available commercial heaters to preheat the engine on the ramp, where no field-supplied power source is available. Portables such as the Red Dragon work just fine.

12 Volt D.C. Self Contained Red Dragon Engine Preheaters (http://www.flameengineering.com/Preheater_Self_Contained.html)

One keeps the cowl on, with insulating blankets, and experiences no damage.

[A and C]

Please tell more about Your problems with Multi-Grade oil.

[Mickey Kaye]

Dead easy and dead cheap.

One 40 Watt light bulb in a car mechanics inspection lamp slid under the cowling for a couple of hours before the flight.

Does the job.

[IO540]

One 40 Watt light bulb in a car mechanics inspection lamp slid under the cowling for a couple of hours before the flight.

This leads one to think of a more effective way.

Th crankcase and sump and made of aluminium, and I wonder if there is a product based on a heating element which could be attached to one of the (many) screws which are all over the place. Such a heater would be left permanently attached, and would be wired to a connector somewhere. A small device could easily dump 100-200 watts into the engine in this way.

Of course it depends on how much one is trying to heat the engine up by. The UK is rarely that cold... -2C right now (Sussex).

The installation would have to be signed off - a Minor Alteration would probably do.

[DERG]

You need a 110V 60Hz preheater. Use a stepdown from the UK supply.
Don't mess with other oils. Stick to the book. You can start them when new in an emergency but even then you gotta sit in 'em for 15 mins to get the temp up before thottle. Not rocket science.

When you sit in 'em during warm up NO THROTTLE.

Engine prime with the ignition off...please note...turn the prop 12 full turns....please note..if uncertain DO NOT DO THIS.

[Finn47]

At my home airport, Helsinki-Malmi (minus 20 C yesterday) winter ops would be impossible without preheat. The airport provides electric outlets (230V, 16A) on pylons, adjacent to about 50 of the parking spots on the apron, for a monthly charge. What we use for the Cessnas which are not hangared - space is scarce - is 1200 W Defa car heaters placed inside the air intakes. If it´s really cold, 2 heaters per aircraft. Going on all night and all day. It works, too. Since 1969, in fact :ok:

[Pilot DAR]

Merry Christmas everyone!

A bit of thread drift, but I was asked...

My choice to not use multi grade oil in my aircraft, is based upon several bad experiences....

When I first bought my C 150, Phillips 20-50XC oil was easily available to me. I found sticking exhaust valves to be a problem (not that O-200's are not known for this anyway). As I worked at an aircraft engine shop at the time, engine teardwn and inspection were not a problem for me. I found that an unpeasant black glass like substance had formed all over the exahaust valve/stem/spring/rocker area. I cleaned it all out, and went again. Months later, same thing... I cleaned it out again.

This time, I switched to Aero Shell 15-50. No more black glass, or sticking valves. During this time, we had two big Continentals come in, both of which had experienced momentary prop runaways in cruise flight. This was accompanied by very low oil pressure indication, but reported normal temps, at cruise power. Both engines went through inspection with no defects found. Both owners changed to straight grade oil, and the problem was never reported again.

Then one day, I was orbiting a friend's place, so he could take pictures. I glanced at the oil pressure, to see with great alarm that it was near zero. Temp normal for a summer day. I pulled the power off, and landed on his runway. When I shut down, and checked the oil, it was the consistancy of a mineral solvent (we call it "Varsol" here). I was very surprised. I left the plane to cool for a few hours.

When I returned late in the afternoon, I checked the oil again, and all was "normal". I fired up for a tem minute flight home. Good oil pressure and temps. By the time I was arriving at home minutes later, the oil pressure was at zero again. After landing check, like Varsol again. The next day, I checked the oil, normal again, fired up, all normal, and flew up to my local airport to buy new oil. By the time I got there (less than ten minutes flight) zero oil pressure again, temps normal. That oil had less than 50 hours and a few months running on it, in an O-200, which does not work oil hard to begin with. Others I spoke with at the timep said they had heard of this too...

Since then, I have chosen straight grade 80 Aero Shell, and never had a problem. As I always preheat in cold weather, I never have a problem starting, and otherwise, with a winter kit when required, I have never had the slightest problem with oil.

I know that multi grades are popular, and to each their own, but I don't see myself using them again, inless the engine specifically requires them.

[S-Works]

I have used multigrade on 3 engines fir nealy 3000hrs combined without a problem.

[POBJOY]

Can not fault it as long as the motors in good order to start with.
Nothing wrong with the W80 or 100 but i think they favour warmer climes than the n europe average.

[Big Pistons Forever]

I think Pilot DAR is in the minority with his refusal to use Multigrade oil. Pretty much every commercial operator of piston aircraft I know uses either Red Ram (Philips) 20-50 or Shell semi-synthetic 15-50. Although the latter is more expensive so its use seems to restricted to turbocharged twins.

When I bought my little Grumman AA1B in the late fall 10 years ago the previous owner had used straight 80 oil. he had changed the oil 5 hrs prior to the sale so I flew the oil for another 20 hours. I then changed to 20-50. There was no question that on a typical Canadian West Coast winter day (ie +5 deg C) the engine was easier to crank and showed oil pressure as soon as it started as compared to a few second delay with the old straight oil. If there is any downside with Multi Grade oil I think it is on the hot side. Even though 20-50 is notionally a 100 weight oil on the hot side, engine do run seem to run cooler with staight 100. If the aircraft where based in a hot climate I would change to straight 100 during the summer, particularly for cooling challenged aircraft like the Grumman.

There is a aircraft mechanic at my home field who is widely considered to be an engine savant. He thinks there is no reason to preheat engines using Multigrade oil at temperatures at or above 0 deg C. After working on many hundreds of engines he has found no evidance that not preheating reduces engine life, a feeling that seems to mirror the experience of the UK piston aircraft fleet. Below 0 deg C however he thinks a whole engine heating system (not just the oil) should be used.

As an aside there does seem to be a fairly widespread problem with students and new pilots starting engines when it is cold. I think this is due to a reluctance to give the engine enough prime and is IMO a result of flying schools propagating the urban legands of aircraft which postulate that there is an exteme danger of having the aircraft burst into flame if one ml too much prime is used. At 5 deg C a C 172 needs 2.5 to 3 full shots of prime and at 0 deg 4 shots. An unsuccessfull start (ie the engine fires but then dies) will require more prime before cranking.

[IO540]

I use AeroShell 15W-50. It's expensive but trivial on the cost of flying - about £60 for the 50hr service.

I did a number of alternates with Exxon Elite and the oil analysis never showed any pattern, so I think the two are equivalent as far as straight wear is concerned. Now I just use Shell because it is a bit easier to get where I am.

The fuel injected engine starts immediately, every time, from any "cold" temperature. Hot starts are a different matter (as any FI owner knows) but with a powerful starter motor it is sorted anyway.

There is a separate issue here in the UK, caused by most school/club billing being WET and charged brakes-off to brakes-on. So renters do as much as they can before letting go of the brakes. They start the engine and do the engine tests as soon as they reach them on the checklist, while it is still cold (there is usually no properly working engine oil temperature gauge anyway) then they race like crazy to the runway... I see this all the time.

[SkyHawk-N]

I have a Tanis heater on my engine. A heating pad on the sump and heating probes on each cylinder. Plug it in and 30-60 minutes later the engine is pretty warm. Purchase and installation is cheap.

[bbrunton]

My preheat indicator is the engine dipstick.

If you pull out the dipstick and you can get a drop of oil to drip off of it, then the oil is will flow for start up. If the dipstick looks like a popcicle on a dipstick, and oil will not drip off, then you will need to preheat.

When you preheat in the usual fashion using external heaters, put them at the cowl flap area not in the intakes. Remember, heat rises. Block the air intakes so the heat will not escape and put a blanket over the cowl if you can.

Preheat usually takes a while.. Remember, if you reach in and the feel the engine, and it feels warm, that is not the crankshaft or the cam that you are feeling. It will take a few hours for the heat to reach them.

Electric heaters such as Tanus that are permenately installed are very good. Dip stick heaters tend to just heat the oil around the dipstick, and not the whole engine.

Turbo charged engines with their external plumbing to the turbo shaft bearings and the waste gate are another story. They should be preheated if the temperature is near or below freezing to prevent congealed oil in the external lines. Congealed oil in the right place in the waste gate line can mean you will be in for a big surprise on start up.

An airplane in a closed hangar can usually be much warmer than the outside overnight air temperature.


Bill

[CanAmdelta1]

Just a quick FYI on external heating and nose plugs.

I believe you will experience more efficient and quicker heat up if the external heat is placed towards the rear and low on one side of the engine (with the nose plug installed on that side) and the nose plug removed on the other side of the engine.

This causes a positive flow of hot air around the entire engine and allows it to exit on the unplugged side. This flow pretty much ensures even preheat.

Of course as mentioned in a previous post a insulated wrap is also used.

Cheers, very informative comments!

[SNS3Guppy]

Th crankcase and sump and made of aluminium, and I wonder if there is a product based on a heating element which could be attached to one of the (many) screws which are all over the place. Such a heater would be left permanently attached, and would be wired to a connector somewhere. A small device could easily dump 100-200 watts into the engine in this way.

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Various other systems are in common use, including systems that ring each cylinder to heat the engine prior to start. Used with a blanket or cover, these are effective means of heating the engine. Some use a portable generator, some use a propane or other fuel fired heater to inject hot air into the cowl.

Lycoming SI 1505 addresses preheat on Lycoming engines. While I realize that waves, carburetor heat, atmospherics, mixture settings, and of course preheat requirements are different within the geopolitical borders of the UK than the rest of the world, as told to us by genuine UK private pilots, what would happen if we looked to Lycoming for answers regarding Lycoming engines? Is it possible that Lycoming might have some input on the matter, even if it's within the borders of the UK (where physics and of course manufacturer input are artificially suspended)? Let's look:

http://www.tanisaircraft.com/UserFiles/File/Lycoming%20SI1505%20Cold%20Wx%20Ops.pdf

The use of pre-heat will facilitate starting during cold weather, and is required when the engine has been allowed to drop to temperatures below +10°F/-12°C (+20°F/-6°C for –76 series engine models).

Interesting, that word, "required." If someone has a dictionary, look it up. See if it still means what it used to mean, will you?

I recall mentioning that a heated dipstick can damage the oil, but let's see what Lycoming has to say:

The use of a heated dipstick is not approved because heat is not distributed throughout the engine, and concentrated heat may damage non-metal engine parts. Proper pre-heat requires a thorough decongealing of all oil.

Interesting. Imagine that. What does Continental have to say on the matter? SIL 03-1 addresses the subject:

http://www.tanisaircraft.com/UserFiles/File/Continental%20SIL%2003-1%20Cold%20Wx%20Ops.pdf

Preheating is required whenever the engine has been exposed to temperatures at or below 20° Fahrenheit / -7 degrees Centigrade (wind chill factor) for a period of two hours or more.

There's that word, "required," again. As we already looked it up, we needn't review it once more.

Continental is a little more direct and forceful with their comments regarding preheating, particularly with their opening warning (bearing in mind, of course, that aircraft registered in the UK, and the pilots operating them, are exempt from these conditions, and the laws and principles of engine operation, metallurgy, and physics from which these warnings are derived):

Failure to properly preheat a cold-soaked engine may result in oil congealing within the engine, oil hoses, and oil cooler with subsequent loss of oil flow, possible internal damage to the engine, and subsequent engine failure.

Superficial application of preheat to a cold soaked engine can cause damage to the engine. An inadequate application of preheat may warm the engine enough to permit starting but will not de-congeal oil in the sump, lines, cooler, filter, etc. Congealed oil in these areas will require considerable preheat. The engine may start and appear to run satisfactorily, but can be damaged from lack of lubrication due to the congealed oil blocking proper oil flow through the engine. The amount of damage will vary and may not become evident for many hours. However, the engine may be severely damaged and may fail shortly following application of high power. Proper procedures require thorough application of preheat to all parts of the engine. Hot air must be applied directly to the oil sump and external oil lines as well as the cylinders, air intake and oil cooler. Because excessively hot air can damage non-metallic components such as seals, hoses, and drives belts, do not attempt to hasten the preheat process.

Scary stuff, but fortunately, UK residents are exempt, right? These things don't happen in the UK, right?

Standby for more scary stuff (disregard if you're beyond the principles of mechanical motion, because this may not apply to you):

Attempting to start your engine with a partially discharged aircraft battery may result in damage to the starter relay, possible engine kick-back resulting in a broken starter adapter clutch spring.

Engine starting during extreme cold weather is generally more difficult. Cold soaking causes the oil to become thicker (more viscous), making it difficult for the starter to crank the engine. This results in slow
cranking speeds and an abnormal drain on the battery capacity. At low temperatures, aviation gasoline does not vaporize readily, further complicating the starting procedure. Always use an external power source when attempting to start your aircraft engine in cold weather.

"Always" sounds a lot like that "required" we read about a couple of times, earlier. Dictionary still available?

More warnings. Be forewarned that the second one is really, really scary. Harry Potter scary. Death, injury, all that. (Don't look those up. You don't want to know).

Do not operate the engine at speeds above 1700 RPM unless oil temperature is 75° Fahrenheit or higher and oil pressure is within specified limits of 30-60 PSI.

Operation of the engine above 1700 RPM before reaching minimum oil temperature may result in engine malfunction, engine failure, injury or death.

I added the last quote there, because I've read posters here telling us before that the engine will never reach operating temperature, and doesn't need to be, before takeoff. If we wait for the temperatures to get up there, we're sometimes told, we'll wait all day, and we can't do that when we're renting. it's too expensive. (Far more expensive than being fit for a casket, for example). Disregard if this doesn't apply to you.

Now, if you're using a combustion heater, Continental will (and does) tell you:

Proper procedures require thorough application of preheat to all parts of the engine. Apply preheated air directly to the oil sump, oil filter, external oil lines, oil cooler, coolant radiator and cylinder assemblies. Continue to apply heat for a minimum of 30 minutes.

If you're using an engine-mounted heater, Continental will (and does) tell you:

Engine mounted preheating systems should include individual cylinder head heater thermocouples, oil sump heater pad and crankcase heater pad. The use of a nacelle blanket will increase the effectiveness of engine preheating.

In other words, heat the whole engine. Go figure. Not just the oil, but the whole engine. If you own a Volkswagen vehicle, you're exempt, because you know better than Continental, and of course if you live in the UK, none of this applies to you, anyway.

Begin preheating of the engine at least 5 hours prior to expected departure. However, do not leave the engine preheating system in operation for more than 24 hours.

Five hours? What? You can't simply show up, jump in, and go? It requires some preparation? Some forethought? Not if you live in the UK, of course, but everywhere else, one may actually have to start preparing for this operation a little early.

Now...there's always the redneck engine heater, using the mechanic's trouble light with the lightbulb, sitting on top of the cylinders around the clock...doesn't actually warm the engine through, but it's cheap, in common use, and in many cases gets left on all the time. Setting aside the fire hazard issue, Continental does have something to say about leaving heaters on all the time. The redneck lightbulb method qualifies as "engine mounted" as it's sitting in the nacelle all the time while in use:

Do not leave an engine-mounted pre-heater system on for more than twenty- four hours prior to flight. Continuous operation of engine-mounted preheater systems may result in aggressive corrosive attack internal to the engine.

The rationale behind this may not seem intuitive to some. Corrosion in oil is largely promulgated by the washing of acids of crankcase walls, chiefly from condensation. Acids settle in the oil and attack bearing surfaces and other areas in the engine, leading to pitting and other corrosion. Additionally, the circulation of the oil around the engine circulates the acidified oil to all parts of the engine, where it can go to work on the components of the engine and propeller when the engine is at rest. Each time condensation forms, the water washes more acid into the oil, and the water itself suborns corrosion as well.

Depending on the nature of the heater in use, heating part of the engine can result in a continual supply of condensation to various parts of the engine. Additionally, continual heating in one part of the engine using electronic means can overheat oil locally, causing chemical changes in the oil in the same way that dipstick heaters tend to do. Another, obvious problem with leaving the heating system in use all the time is the fire hazard.

Regardless of the method of preheating, save for those in the UK who are exempt, we can see that both Lycoming and Continental strongly recommend and even require it: it is not a "fossil recommendation."

[Pilot DAR]

SNS and I agree. He has found the text to confirm what I have done for 25 years. Basic physics and operational requirements or given conditions, don't really change to suit the operator's convenience. You just gotta do it right!

I need add very little to SNS through disseratation. I have used the "100W Mechanic's light" with success under the limited conditions of: a; no alternative, and b; right after shut down to keep the engine warm (not get it warm), and c; with a fitted insulated engine blanket. This means is still quite risky from a fire prespective though, and a last resort.

It is known to carry a small generator in the plane for overnight trips, so it can be run to energize heaters hours preflight.

For all the other care we take, let's get this right too!

[Zulu Alpha]

I seem to remember that there was a problem with some of the multigrade/synthetic oils if you changed to them after running the engine on non multigrade for some time. IIRC it was caused by lead build up with the std oil. The lead was then removed by the multigrade which gave problems with oilways blocking as so much of it was dumped into the oil.

If you ran the engine on multigrade from day one, then the lead didn't build up and there wasn't a problem.

[IO540]

Another long pompous dissertation from James Bond who flies solid IFR while under small arms fire... he should set up his own pilot forum, where only holders of eight gold stripes can join up.

Pprune is mostly a UK/European forum. The UK is rarely -6C or -12C.

If it is, which is extremely rare, prob99 you cannot get to the airport.

The lowest temp I have ever seen since coming here in 1969 was -8C, and indeed EGKK is -8C right now

EGKK 260520Z 00000KT 7000 NSC M08/M09 Q1029 582900//

Somebody I know up north is apparently seeing -19C but there is no chance of anybody driving around up there anyway. The car door doesn't even open, I hear.

If I tried to open the door on the plane in these temps, there is a good chance the door seal will be stuck to the other half and will rip off.

If one was parking outdoors and had an engine heater out there, unattended, the engine heater would get stolen pretty quick (at all but the H24-secure airports, and most of the latter do not allow GA parking anyway).

Elsewhere in N Europe, things get colder and -20C is common, but they tend to have equipment to deal with it..... like hangars :)

I seem to remember that there was a problem with some of the multigrade/synthetic oils if you changed to them after running the engine on non multigrade for some time. IIRC it was caused by lead build up with the std oil. The lead was then removed by the multigrade which gave problems with oilways blocking as so much of it was dumped into the oil.I made that change twice (1x when new and 1x after the Lyco crank swap job) and never saw this.

No idea where this story originates but it could be with the pre-1960s crankshafts which had what I vaguely recall were calles slush tubes and those had a history of getting bunged up anyway; somebody tried to sell me one of those in 2005... But I never saw any big lead % in the oil analysis anyway.

[SNS3Guppy]

I seem to remember that there was a problem with some of the multigrade/synthetic oils if you changed to them after running the engine on non multigrade for some time. IIRC it was caused by lead build up with the std oil. The lead was then removed by the multigrade which gave problems with oilways blocking as so much of it was dumped into the oil.

If you ran the engine on multigrade from day one, then the lead didn't build up and there wasn't a problem.

Lots of misconceptions on oil. The subject is preheat, of course, but let's tackle oil.

The standard misconception is that mineral oil leaves varnish, which is then removed by the use of synthetic oil. The varnish theoretically ends up potentially plugging galleys, etc. There's no lead buildup.

Another popular misconception is that there's mineral oil, AD oil, and multiweight oil. They're all mineral oil, and they're all compatible. That is to say, straight weight oil is mineral oil, as is multi weight.

There's no issue with running alternating straight weight and multigrade oil. Traditionally, straight weight oil has been used for the break-in with a new cylinder, top overhaul, overhaul, or new engine, followed by the operator's choice of oil (often multigrade). I've worked for a number of operators who preferred straight weight in the summer, and multi-grade in the winter.

A brief period of time involving a series of lawsuits against Phillips for their XC-II oil caused some disharmony in the community and displeasure regarding multigrade oil. Current XC oil works for both break-in, and regular every day ongoing operation. Switching between this and straight weight won't cause contamination or varnish issues.

Another common misconception regarding oil is the change interval. Some feel it should be based on hours alone, but it should be by calendar interval as well as hours. An airplane which doesn't fly all year still needs regular oil changes. An airplane which flies regularly needs regular oil changes, too. It's a whichever-comes-first proposition.

Pprune is mostly a UK/European forum. The UK is rarely -6C or -12C.

If it is, which is extremely rare, prob99 you cannot get to the airport.

The lowest temp I have ever seen since coming here in 1969 was -8C, and indeed EGKK is -8C right now

The service instruction from both Lycoming and Continental states that preheating is required by minus seven to minus 12 degrees. It doesn't say it shouldn't be used at higher temperatures, or that it's not a good idea. Anytime the temperatures are freezing or lower, preheating is a very good idea.

However, as you noted temperatures presently are minus eight, then you're a degree colder than the required preheating temperature for Continental powerplants.

No idea where this story originates but it could be with the pre-1960s crankshafts which had what I vaguely recall were calles slush tubes and those had a history of getting bunged up anyway;

Actually, modern, current crankshafts applied to constant speed propellers use sludge tubes, and they do require cleaning at overhaul, as they do contain sludge. Hence, the name.

Somebody I know up north is apparently seeing -19C but there is no chance of anybody driving around up there anyway. The car door doesn't even open, I hear.

If I tried to open the door on the plane in these temps, there is a good chance the door seal will be stuck to the other half and will rip off.

This really makes you wonder how the rest of the world manages to get along in cold weather, doesn't it? Operations in much lower temperatures than that are common in some places...without ripping off door seals...and yes, preheating is standard fare. You might even be shocked to know that in many locales, preheating automobiles is common.

If one was parking outdoors and had an engine heater out there, unattended, the engine heater would get stolen pretty quick (at all but the H24-secure airports, and most of the latter do not allow GA parking anyway).

The intelligent person would put the preheater in their car, or leave a lockbox in the tie-down spot, like many owners do. Perhaps that's too much progressive thinking for the UK, though.

[A and C]

As has been said above there is no problem with mixing Multi grade and other aviation piston engine oils, however I would not bother if the engine is more that 50% through it's life as the advantages of the Muilt-grade are unlikely to be of any benifit for the increased cost and the multi grades do have a habit of "cleaning" the engine so you have to inspect the filters more regularly over the first 100 hours or so when changing to multi grade.

The lead thing is a red herring. lead build up in the oil ways was as a result of using a pure synthetic oil in engines running leaded fuel, synthetic oils can't hold in suspension the lead that has blown by the piston rings and so the lead is centrifuged out of the oil in the rotating parts of the engine hence the lead build up in the sludge traps and eventualy the crankshaft oilways. The major oil company that was marketing FULLY synthetic oil should have known better!

Semi-synthetics are OK as the mineral part of the oil can hold the lead in suspension untill the oil change at 50 hours, I would not run a semi-synthetic oil past 50 hours as the ability of the mineral part of the oil to hold the lead in suspension is limited.

Mr Guppy seems to be unable to understand that the climate in the UK at the moment is unusual in and so it is highly understandable that we are about at prepaired for it at Hawaii would be for snow. the other thing that he forgets is that the VOLUME of the water content of the presipitation and could air is much higher than the "dry cold" of the mid continental USA and brings different problems.

We also have a bunch of reguators who are (in EASA) just pen pushers and so don't understand the first thing about aviation and so the cost of fitting a pre heat system to an aircraft is not viable for the few days when you might need it. That is always provided the runway has been cleared of snow!

We may have to review these things over the next few years in view of climate change, IO540 is on the south coast and had -8C last night I am only about 70NM inland from him (EGTB) and had -14C last night so I think things are changing.

[DERG]

Got the answer from my oracle person. You cannot start this engine unless you preheated. If ambient is below 6C DO NOT START the engine.
Reason:tolerances are too tight. Consequences: bore scratching.
Has FA to do with the oil apparently..all to do with this Lycoming Alu design.

[A and C]

I take it that 6C is a typo and you mean -6c.

[Malcom]

Mr Guppy is unbelievably ignorant of just how lucky he is in FAAland. If I want to fit a Tanis heater to my UK engine - totally independent of any aircraft systems - I have to submit a mod including the the full spec of the ins and outs of a ducks backside, a blank cheque and an open-ended completion date expectation to EASA for a total benefit of perhaps 14 days extra flying days per year, 13 of which I cant get to the airfield which wont be open anyway. We dont bother with winter prep like preheating or airfield clearing because its just not cost effective or worth the bother to anybody in the UK. Only just a couple of years ago the run-up to Xmas was T-shirt weather - what use a preheater then?

BTW, interesting reading - manufacturers recommendations & SBs etc suddenly becoming gospel when previous recitations on various subjects made us believe he knew far more than Messrs Lycoming & Continental.

Also BTW, my hovercraft has heated windows and a squiffy heater unit, so I'm fully prepared. The eels can stay outside.

[IO540]

If we had -8C for weeks every winter, UK GA would grind to a halt, because in most places hangarage is scarce (and costs say £500/month when you can get it) and one cannot usually park the car close enough to the plane to unload heavy equipment.

We would have to get seriously sorted, but most owners would still be grounded because they simply don't have a solution to pre-heating the whole plane.

The Americans have it easy. At most places, they can drive right up to their plane, unload stuff, etc. They have fantastic FBO facilities, with warm rooms, showers even, and even courtesy cars which are sometimes free.

[Saab Dastard]

This is another thread degenerating into sarcasm and personal animosity.

I don't particularly want to spend my holiday having to keep a lid on your puerile behaviour.

Any more (and you know who you are) and you will be banned from this thread and / or PF forum.

SD

[DERG]

Nope, plus 6 centigrade. As per the book.

[No Foehn]

A hairdryer poking into the engine cowling for half an hour works a treat for me (and I'm starting from -20C).

[IO540]

A quick google....

Here (http://www.aerosportpower.com/docs/540seriesopsmansec3a-operatinginst.pdf)

4. COLD WEATHER STARTING. During extreme cold weather, it may be necessary to preheat the engine
and oil before starting. [no values given]

This famous Lyco flyer (http://www.lycoming.textron.com/support/tips-advice/key-reprints/pdfs/Key%20Operations.pdf) says (page 15 of the PDF)

For most Lycoming models, preheat should be applied anytime temperatures are at 10˚ F or lower. The exception to this rule is the 76 series models that include the O-320-H, and the O/LO-360-E. These engines should be preheated when temperatures are below 20˚ F.

and uses the word "guideline". 10F is -12C and 20F is -6C.

Then you have piles of "urban knowledge" e.g.

here (http://www.vansairforce.org/articles/EP/eng_lyc_care_feeding.shtml)

Never attempt a start below freezing without pre-heating

Assuming they mean freezing point of water, that is 0C.

If somebody finds a current Lyco document speaking of mandatory preheating below +6C I will eat my EDM700 :)

This (http://www.reiffpreheat.com/product.htm) is an interesting product.

[SNS3Guppy]

Mr Guppy is unbelievably ignorant of just how lucky he is in FAAland. If I want to fit a Tanis heater to my UK engine - totally independent of any aircraft systems - I have to submit a mod including the the full spec of the ins and outs of a ducks backside, a blank cheque and an open-ended completion date expectation to EASA for a total benefit of perhaps 14 days extra flying days per year, 13 of which I cant get to the airfield which wont be open anyway.

Ignorant? I spend plenty of time in EASA-land, as well as numerous other jurisdictions, too. You're correct: my maintenance qualifications are FAA certification, and I'm quite content to operate within those bounds.

You do not require a field approval, however, to operate a combustion heater, which will easily fit in the trunk (or "boot") of your car.

There's more than one way to skin a cat, more than one way to wet a duck (and it's backside), and more than one way to preheat an engine. The manufacturer recommended method involves a heated hangar. In lieu thereof, other methods are available.

This is an interesting product.

Reiff makes an excellent product.

[Ultranomad]

This may not be directly applicable to most engines people are flying these days, but as a matter of academic interest, let's not forget two more techniques fairly popular in the past:
- If the engine has an easily accessible drain cock, drain the oil while it's still warm, come back next morning with a pail of preheated (+50...60C) oil.
- At the time of shutdown, dilute the oil with avgas. While you are starting the cold engine, this will reduce the oil viscosity; as the engine warms up, the fuel will evaporate and the oil will return to its normal viscosity. Radial engines are often equipped with an oil dilution valve directly in the fuel system. Many winters ago, when it suddenly got as cold as -30C, I used this technique on my UAZ (http://en.wikipedia.org/wiki/UAZ-469). With undiluted oil, the starter would barely crank the engine even with a warm battery, so it had to be towed for a few minutes to get started. A cupful of petrol into the oil in the evening would allow me to start in the morning without any problems. (Once again, this should not be construed as an endorsement of this method unless allowed by the manufacturer; Lycoming explicitly discourages (http://www.lycoming.textron.com/support/tips-advice/key-reprints/pdfs/Key%20Maintenance.pdf) it).

[SNS3Guppy]

Draining the oil overnight, and oil dilution have already been addressed. Draining oil is a start and addresses the oil, but doesn't address the need for preheat, with or without having prepared the oil.

Oil dilution is a function of mixing a lubricant and a solvent and does result in chemical changes to the oil, as previously discussed.

Radials have used oil dilution in some cases, but so have horizontally opposed recip engines. With good reason, this option is no longer offered in airplanes such as the Cessna 206 (where it was once a common option), and oil dilution has been removed or deactivated in nearly all light airplanes.

[Ultranomad]

Draining oil is a start and addresses the oil, but doesn't address the need for preheat, with or without having prepared the oil.
Well, it will obviosly vary from engine to engine, but a bucketful of hot oil + some careful cranking may be enough to bring the engine to its starting temperature if it isn't very cold outside.

BTW, speaking of external combustion heaters... Just a couple of weeks ago, a Mi-8 helicopter in Russia was destroyed by fire after an explosion of the ground-based heater. If you use one, always have a fire extinguisher within easy reach.

[CanAmdelta1]

IO540

Something we find useful in the North country, especially for automobile doors, is WD 40 spray. We open the doors and spray it on the latch and inside door jam. This prevents doors from sticking/freezing.

hope this helps

[SNS3Guppy]

If you use one, always have a fire extinguisher within easy reach.

Always have a fire extinguisher handy during any engine start.

Something we find useful in the North country, especially for automobile doors, is WD 40 spray. We open the doors and spray it on the latch and inside door jam. This prevents doors from sticking/freezing.

Dry lube silicon spray does the same thing. It doesn't attract dust or leave residue that can attractdust or dirt.

[DERG]

Took me five attempts at getting logged on this site..think I am unwelcome.

Why not just stick to the Lycoming handbook. If you have to preheat take the machine where you can use a popane fired 230/110V space heater on the front end and do it that way.

Of course I realise a lot of people who own these machines are not artisans. It is going to cost you money what ever you do.

[Pilot DAR]

Preheaters which involve a lot of hot air work well, as long as they are properly used. If the hot air involves actual fire, it is obviously very undesireable in the engine compartment. I have ferried for repairs two aircraft which had wiring fires in the engine compartment, bacause of the over zealous use of "propane" heaters.

Unfortunately, one of the three areas of the engine, the crankshaft area, is also the deepest in the engine. Cylinders and oil sumps are relatively easy to preheat by various means, but it takes a long time for heat to warm the crankshaft.

I use the proper electric oil sump heater, and switch in on for at least three hours before I fly. The heat rises well from the oil sump up, and throughout the cowl, and warms the whole engine. Those who blast in a whole bunch of hot air (least effectively into the upper cylinder area) for a "short" duration (less than 30 minutes) are probably fooling themselves. That heat has had little effect on the crankshaft, which is the most expensive part of the engine to be turning over with ineffective lubrication.

Slow and easy does it best.... like so many things in aviation....

[SNS3Guppy]

A blanket around the cowl, with the heat inserted under the engine using scat hoses, over the course of several hours, works well. I've seen people burn the paint off cowling on light airplanes by attempting to put too much heat in too fast, especially through the inlets at the top of the cylinders (where it doesn't do much good.

Heat rises, of course, and allowing the engine to warm from the bottom, up, means that the entire engine eventually gets warmed. Manufacturer recommendation is to allow at least 5 hours for proper preheat, when using forced air.

I have also seen pilots cause leaks or damage seals by starting in cold weather and cycling a propeller full of cold, congealed oil.

Pre-oilers are good investments for those operating in cold weather, but rearlly are a wise investment for those operating in any kind of weather. Interestingly, they're not seen very often, any more. A preoiler circulates oil before the engine start, throughout the engine, to prelubricate (and warm) the engine. They're also useful for post flight shutdown lubrication and cooling.

[flybymike]

Heat rises, of course

Hot air rises, and there is usually plenty of it on this forum. Heat radiates conductively via the path of least resistance.

[SNS3Guppy]

Actually, heat transfer by conduction, convection, and radiation are entirely different processes.

In the case of preheating an engine by forced air (external combustion heater), one is initially using the convection process for heat transfer, then relying upon the conductive properties of the metal.

In a given medium, heat conductivity relates to the thermal resistance of the material. The second law of thermodynamics provides that heat transfer is from the point of highest temperature to the lowest. One will heat the engine the most thoroughly and the fastest by heating from beneath, rather than above the cylinders, and allowing convection and conduction to transfer the heat upward, rather than down.

Heat in oil rises, heated air rises, heat in the engine rises, and yes, when conducting heat through the engine, including the application of heat at the sump, heat rises. The lower portions of the engine will be the first to cool, and should be heated first. After shutdown, the lower portions of the engine cool first, or fastest. Even in operation, the upper portion of the cylinder and upper spark plug tend to receive the greater heat, which is part of the reason that airflow through the cowling is directed at the upper half of each cylinder in a horizontally opposed installation, with airflow generally being aft and downward from there, in a pressure cowl installation.

[DERG]

SNS

Yes. Basic physics education for blue collar kids was lost in the UK around 1968. We now have a whole generation of people who had the money but not the understanding. They did the couse but knew SFA once they had passed the exam. This is part of the issue with the UK. They make up their own rules then invent the reality to match. You are not alone.

DAR

Tell em as it IS! They need a heater. Happy Holidays!

[Fly-by-Wife]

heat in the engine rises

Not unless you are melting it, it doesn't!

when conducting heat through the engine, including the application of heat at the sump, heat rises

Complete tosh. The molecules of metal in the engine are not free to move about like air or water (or other fluids, e.g. molten metal) and change density.

Therefore there is no lowering of density, and no heat rising in the metal of the engine.

If you are able to show me bubbles of pistons rising through denser, cooler cylinder heads then I will believe that metals can heat via convection!

FBW

[Deeday]

Complete tosh. The molecules of metal in the engine are not free to move about [...] Therefore there is no lowering of density, and no heat rising in the metal of the engine.

To be fair, by heating the bottom of the engine, the outside air around it will presumably receive some heat too and then rise, transferring some heat to the top of the engine by convection.

Whether the amount of heat transferred this way is significant, compared to the amount of heat transferred internally by conduction, is debatable, but could be enough to make bottom-up heating preferable to top-down.

[pulse1]

If we're getting all scientific about this, does anyone know the heat capacity of engine oil. We always put a 1kW fan heater inside the cowling and under our 0-200 for 30 minutes before a very cold start but I would be surprised if it had much effect on oil temperature.

We use it to warm the carburettor and induction system so the petrol vapour stands some chance of getting up to the cylinders before condensing (no primer, just an accelerator pump). With sufficient sucking in it always starts immediately after being in an unheated hangar at about -5C. Sometimes it stops again just as the oil pressure is coming up and, although it restarts with a couple more primes, I've never understood why.

[IO540]

does anyone know the heat capacity of engine oilDon't know about yours but an IO540 is about 160kg total weight, excluding externally mounted accessories and the exhaust. Of this, the oil is only about 8kg.

The crankshaft (http://www.peter2000.co.uk/aviation/engine-rebuild/crank-whole.jpg) is probably the heaviest single item, at about (I guess) 20kg. The rest is all the various bits; some are ally, some are brass, and probably most of the weight is steel.

Taking a very average specific heat capacity (http://www.engineeringtoolbox.com/specific-heat-metals-d_152.html) as 0.7 (kJ/kg/K) this means that 100W (actually transferred into the engine mass) would make its temperature rise by 3C per hour.

I hope I got that calculation right :) Obviously it ignores heat losses from the engine, which will start to occur as soon as its temperature rises above ambient.

That is quite slow, but it probably represents the top end of what can be achieved by poking a heated probe down the dipstick hole.

If the dipstick heaters damage the oil they must be of crap design. On my engine, with 9 qt of oil, the bottom 3"-4" of the dipstick is immersed. If the dipstick hole is in a large pool of oil, then convection will easily carry away 100W, with a temp rise of the order of 10C in the immediate vicinity of the heater. If the dipstick hole is tight around the dipstick then heat will be efficiently transferred into the crankcase by conduction through the layer of oil. The important thing would be for the heater to be temperature controlled (which I guess none of them are) and to heat only the fully immersed portion. The most worrying thing would be if the heater breaks off; the engine will then have to be dismantled to get the bits out :) :)

And 100W might be what actually ends up in the engine from a 1kW fan heater poked up the cowling.

So to do it effectively, from really low temps like -10C or colder, one needs a lot more than 100W.

[Fuji Abound]

If you are able to show me bubbles of pistons rising through denser, cooler cylinder heads then I will believe that metals can heat via convection!


Fly-by-wife

Exactly - I am afraid our friend Mr Guppy has always had a rather umm, colourful imagination.

[DERG]

"The molecules of metal in the engine are not free to move about like air or water"

As I said you can PAY for an education and still be ignorant. You are an arts graduate maybe? HS cert? GED maybe?

So tell me FBW what exactly DOES move inside the metal. You can use any model you want as an illustration. The one I use was draughted by Niels Bohr in 1911. It is graphic..it has a pic usually..so I guess you should be able to grasp the idea.:ugh:

[whirlwind]

I have a 60W greenhouse tubular heater resting inside the bottom cowling of my Moth (and switched on), which keeps my Gipsy engine warm enough to start no problem all Winter. Works for me!
WW

[Deeday]

DERG I don't see a problem with Fly-by-Wife's statement. He is trying to explain why heat does not transfer by convection inside solid bodies and pretty much hit the nail on the head.

I have a MEng and a MSc, in case you wonder and never brag about it, unless somebody with that sort of condescending attitude of yours starts posting useless considerations about other people's education.

[Pilot DAR]

Wow, hot topic!

I did not realize how much I did not know about how heat gets from one place, to another. I have just done what works all these years!

Maybe one day, I'll prefect the understanding of physics, but for now, I'm happy to fly warm, well lubricated, and thermodynamically ignorant!

[S-Works]

Personally I just test the igniters, press the start button and watch the ITT......
:):)

[Fuji Abound]

Personally I just test the igniters, press the start button and watch the ITT.....Personally I just test the igniters, press the start button and watch the ITT......

:D he, he, I like it.

[Zulu Alpha]

I have a 60W greenhouse tubular heater resting inside the bottom cowling of my Moth (and switched on), which keeps my Gipsy engine warm enough to start no problem all Winter. Works for me!

There is a downside to this as it will heat the oil in the bottom of the engine. This will drive off any water or acid in the oil which will then condense on the top of the engine which is cold.

This then means that the top of the engine can corrode. Unfortunately this happens to be the camshaft on a Lycoming. Not sure on a Gypsy, but I think it might be the crankshaft.

Lycoming specifically advise against sump heaters being used continuously and only recommend using them just before starting.

I have heard about people who have sump heaters controlled from their mobile phones. This allows them to be switched on a few hrs before you get to the hangar. Does anyone know of any switches that can be controlled by mobile phone as this would allow a very simple remote controlled fan heater to be rigged up.

[POBJOY]

One mans cold start is another's normal start so there is no one fix fits all.
As we are primarily thinking about our UK conditions (and whats more the average facilities) what is needed is a simple application that actually works.
On the basis that most UK airfields and clubs do not have facilities for preheat this leaves it to the owner to organise (what is possible) within the limitations of what the Airfield operator/Hangar owner will allow.
This will NOT include draining and refilling oil outside of a maintenance organisation or wandering around the Hangar/Parking lot with pails of warm oil.
This leaves it down to having the best oil available to cope with the conditions prevailing and if you can get some "safe" heat around the engine beforehand so much the better.
We are not talking about "heatsoaking" the block rather than taking the bite out of the "cold oil" and giving the induction system some help in starting the engine.
If this preparation can be done inside so much the better,if not you may have to make up some simple cowl cover that lets the available heat do some work before it escapes.
If an engine has not operated for some days then it will need more preparation than one flown daily.

[Pilot DAR]

One mans cold start is another's normal start so there is no one fix fits all

Hmmm, I do not agree.... I think that in large measure here, the "men" involved is Mr. Lycoming, and/or Mr. Continental. Their requirements with respect to temperatures for starting have been clearly presented here, and are not in dispute.

As has also been said, conveinence, (or being on any particular island) does not absolve one of conforming as closely as possible to the manufacturer's recommended practices for preheating (or any other aspect of operation).

I agree that the UK does not have weather conditions which would ever make draining engine oil and taking it into your log cabin overnight necessary. but the temperature values below which effective preheat of the engine are required, are clear. It sounds like those do occur in the UK (I have certainly experienced them).

At a minimum, any owner can arrange for a plug in engine preheating system to be installed, buy a properly fitted engine blanket, and a 500W generator. Take the generator to the plane, fire it up, plug, in, come back a few hours later, and you'll be ready to go. I have done this many times, where electriciy was not available.

If this is too much trouble and expense, a much cheaper method is to preserve the engine properly, take the battery out, and fly it next spring. This is what I have done to my second aircraft, a Lycoming powered amphibian, which does not have cabin heat. It sits safely and attended to, but out of service for the season.

The manufacturers of aircraft expect you to take care of them with consideration to the recommended practices. If you choose otherwise, you are taking direct responsibility for the engine's condition in the long term.

If owners are going to develop their own practices with respect to care, operation and maintenance of aircraft, why do people like me go to all the effort to write flight manual supplements, and instructions for continued airworthiness for these aircraft?

[SkyHawk-N]

Fuji Abound said:
If you are able to show me bubbles of pistons rising through denser, cooler cylinder heads then I will believe that metals can heat via convection!

Fly-by-wife

Exactly - I am afraid our friend Mr Guppy has always had a rather umm, colourful imagination.

There is oil in the sump, the bottom of the sump gets heated and this heats up the oil contained in it. The oil then helps to heat the rest of the engine using convection.....does it not? :confused:

[IO540]

If owners are going to develop their own practices with respect to care, operation and maintenance of aircraft, why do people like me go to all the effort to write flight manual supplements, and instructions for continued airworthiness for these aircraft?

I tend to agree but I think there are additional factors:

Lyco/Conti are under immense legal pressure to not change their operating recommendations, irrespective of how much "history" has passed by outside their dusted up windows. This is because many of their engines fail before TBO when they are put together right, and many more fail before TBO because they are not put together right. So they work hard to evade liabilities, and modifying their operating suggestions would be an admission they originally "got it wrong". Hence all the garbage they continue to write re LOP etc. This is probably why they say -12C (or whatever) without qualifying it according to oil type used, which makes the -12C (or whatever) an obvious farce if stated as a straight unconditional figure for a given engine type.

For each type of oil there will be a low temperature below which it doesn't flow well enough to get around a (particular design of) engine fast enough, before it gets a chance to warm up. This behaviour should have been studied (they have been making these things since the 1950s, essentially) and documented, but nothing has been done. It is possible there are owners out there who regularly start at low temps and regularly get trashed engines, but I have not heard of it. Maybe they all preheat, or maybe the problem is not as big as it appears, or is much more engine type specific.

The lowest I have started mine at was probably about -3C, and the oil pressure gauge was up in the green within a few seconds; same as it always is. I don't know (without looking in the engine MM) how far along the oil path that gauge comes off, but it is supposed to be right at the end, for obvious safety reasons. This kind of stuff should have been documented by now.

It is the arrogant unwillingness of the manufacturers to get stuck into some proper research and documentation (and I fully understand why they behave like this - the above legal reasons) which has given rise to countless theories on engine management. Deakin (etc) would have not had anything to say if Lyco/Conti did some proper bench research and were open about the results.

[Pilot DAR]

It is quite true that the Lycoming and Continental operating instructions are probably largely influenced bt liability, and who can blame them for that! Also true that there are many factors which affect the circumstances of a cold start. I am certainly guilty of cold starts for my O-200, and it went through it's last overhaul with no related damage at all.

That said, if owners who are only modestly informed of all of the factors, are thinking to repeatedly "do their own thing", which conflicts with the mfg's recommendations, simply for convenience sake, that's not something I would support. There are lots of "tricks" and half measures which will get a cold engine running, and I'm not relating them here. There's a proper way, and it's clear. If you can't do that, come as close as you can. If you regularly fly in conditions for which a preheat is obviously appropriate, arrangements should be made to provide the required heat. If it's an occasional, unexpected circumstance, then yes, the engine will probably tolerate it a few times.

I don't expect the engine manufactures to invest more effort to further clarify the information they have already presented, with respect to preheat. If they were to do all the research, and sell an STC for "this is how to really cold start your engine", would people pay for it, and happily return the manufacturer's investment in research?

I hold STC's for changed process only for aircraft, and people still try to do it for free!

[SNS3Guppy]

If you are able to show me bubbles of pistons rising through denser, cooler cylinder heads then I will believe that metals can heat via convection!

What part of the convection process do you not comprehend, when putting two hot air scat hoses from a combustion heater in the bottom of the cowl, to warm the engine? That's convection.

Heating metal to metal is conduction, and one doesn't need "bubbles" to transfer heat by conduction.

When preheating via a sump heating pad, one invokes the principles of conduction, convection and also radiation.

In most circumstances in the real world, one method of heat transfer is not present without the other.

You'll find that during engine operation, the upper spark plug in the horizontally opposed recip engine tends to be the hotter plug, which is why the lower plugs tend to be more susceptible to fouling. You'll also find that most light airplane pressure cowl assemblies run cowl inlet air across the top of the cylinders first then exhuast it through the bottom of the cowl; hottest part on top, to lowest on the bottom. Conductive heating, convective cooling.

Shut down, and one doesn't vent the engine through the bottom. Fly your 206 to a desert location and expect to leave during the heat of the day, it's a good idea to vent that cowl. You won't find it in the aircraft handbook, but one can open the oil filler door and oil check door, to vent the cowl best, because heat rises, and the doors are on the side and top of the cowl; this helps vent heat, which makes the follow-on engine start a little easier on a hot day.

This is probably why they say -12C (or whatever) without qualifying it according to oil type used, which makes the -12C (or whatever) an obvious farce if stated as a straight unconditional figure for a given engine type.

Probably? I'm always impressed by uneducated guesswork.

You have the manufacturer data before you. Elect to disregard it at your peril. What part of "required" escapes you? It it a difficult definition, or simply something not found in the UK lexicon?

This kind of stuff should have been documented by now.[/QUOTE

It has been, ad nauseum. Hence manufacturer guidelines on operation.

[QUOTE]It is the arrogant unwillingness of the manufacturers to get stuck into some proper research and documentation (and I fully understand why they behave like this - the above legal reasons) which has given rise to countless theories on engine management.

On the contrary, it's your arrogant unwillingness to buy the company and change the procedures, as you seem to know so much better than the folks who designed, manufactured, and built the engines. With your expertise, you could easily replace the legal department, engineering department, and serve as customer service to tens of thousands of operators who hungrily await your counsel. That you've failed to do so can only be a testament to your arrogance, can it not?

No?

Interesting that it's a testament to the "arrogance" of the manufacturer, then.

More interesting is the fact that the manufacturer has the legal right and responsibility to make those guidelines, requirements, and recommendations whereas you...do not.

I have a 60W greenhouse tubular heater resting inside the bottom cowling of my Moth (and switched on), which keeps my Gipsy engine warm enough to start no problem all Winter. Works for me!

It works until a float sinks, the carb floods, and avgas drips on the light or fills the cowl with vapor. It works until the light finally blows, or a short occurs, or something else happens to cause a fire. It happens.

For each type of oil there will be a low temperature below which it doesn't flow well enough to get around a (particular design of) engine fast enough, before it gets a chance to warm up. This behaviour should have been studied (they have been making these things since the 1950s, essentially) and documented, but nothing has been done.

It has been done, actually, and is well known. Oil flow rates and viscosity is only a part of the picture, however. You'll note that the manufacturers (the ones who know less than you, remember) specify heating the entire engine. Not just the oil. It's an engine preheat. Not an oil preheat. Warming the oil is only part of the process, only one of the reasons for the preheat, as we've already discussed. Your disbelief lies in your ignorance of the matter, but doesn't change the fact.

Personally I just test the igniters, press the start button and watch the ITT......

Turbine cold weather starts: the biggest hazard with cold weather starts in a turbine is a low battery Two solutions are to use a battery heater, and to use external power for the start. Low battery causes hot starts, hung starts, and slow starts, all of which can cause burner can damage and other thermal injury. Even if they never show up as a high ITT. One can do severe damage to an engine and never have it exceed ITT start or takeoff limits, most commonly during a very slow start or a hung start. The high temperatures aren't reaching the ITT probes as the gasses aren't passing through the engine due to the low speed or stagnated airflow: the damage is done prior to the probes.

Some turbine engines do have cold weather limitations, which must be observed. Turbines do make cold weather starts easier, but also present additional hazards.

[Fuji Abound]

This thread reminds me of the Christmas present you really didnt want - how ever hard you try to give it away it just keeps on coming back. ;)

[Zulu Alpha]

I have a 60W greenhouse tubular heater resting inside the bottom cowling of my Moth (and switched on), which keeps my Gipsy engine warm enough to start no problem all Winter. Works for me!
It works until a float sinks, the carb floods, and avgas drips on the light or fills the cowl with vapor. It works until the light finally blows, or a short occurs, or something else happens to cause a fire. It happens

Maybe they don't have these in the US, but they are 60W electric oil filled and you can pick them up with your hand as the surface temp is way less than 100 degC.

They could probably be dowsed in petrol without any problem.

They do still cause condensation in the top of the engine.

[IO540]

Just looked at Mr Guppy's profile and the 4 threads he has started. In one of them he asks

Anybody at Kalitta or Atlas have a line on where one might pick up a copy of a book a pilot put together on the Classic 747, possibly referred to as the "blakely book?" I understand it has a blue cover...looking for someone who knows where one could be purchased. PM with details. Thanks.

[mm_flynn]

A long time ago when I was doing my engineering degree, we were taught the basics of piston design with dissimilar metals. The clearances needed to be specified so that you didn't have blow-by at operating temperatures (and also not excessive gaps in the bearings) but this then resulted in small and potentially negative clearances at low temperatures. We had to specify a 'do not move below' temperature that ensured no combination of manufacturing tolerances would result in a nil or negative clearance. I don't recall ever having an issue specifying a suitable multiple-grade oil, but we always had issues with clearances at low temperaures.

I would be astounded if the manufacturer recommendation is based on anything other than metal to metal clearances (as they already specify oils for different temperatures and probably don't care if a cold soaked battery doesn't have the oomph to crank a cold piston engine to light). Grinding metal to metal that is impossible to lube due to no clearance will definitely be a problem they would reasonably be expected to tell customers to avoid!

[flybymike]

but one can open the oil filler door and oil check door, to vent the cowl best, because heat rises

Aaaarrrggghhh....

[IO540]

I would be astounded if the manufacturer recommendation is based on anything other than metal to metal clearances

Can anyone from colder climates report on having found they could not move the prop by hand (at all) below a certain temperature?

It must be possible but I wonder what that temperature (loss of piston clearance) would be.

[Morrisman1]

It must be possible but I wonder what that temperature (loss of piston clearance) would be.

With the piston being aluminum and the more being steel would this not be an issue?

[Saab Dastard]

Is it Christmas or what - too much time on your hands?

Another thread gone west.

SD