Engineer Ted's How to Make Your Engine Last (while running)

Considering that one of the things I do in the engine test lab I work in is head crack testing, I do believe that there is a potential for problems and/or damage when there are rapid temperature changes. Do I go out of my way to insure that temperatures don't change too rapidly? No, but I also don't go out of my way to create large, rapid temperature changes either.

One of the harshest piston aircraft engine operating environments I've personally been around is in skydive operations, and I haven't seen an excessive amount of damaged or cracked cylinders on those engines. If anything, I'd say they enjoy a longer than normal cylinder and engine lifespan due to actually being used, at least compared to the typical low use privately owned aircraft.
 
but....I'm told the skydiving guys have a few tricks up their sleeve to prevent over temping CHTs.....and it's not so much the cooling that they're worried with.
 
but....I'm told the skydiving guys have a few tricks up their sleeve to prevent over temping CHTs.....and it's not so much the cooling that they're worried with.

The drop zone I occasionally fly at has no climb rate or cylinder head temperature restrictions, time and temperature delta restrictions, or obsessive engine operating regimens. They also often employ ink wet commercial pilots, so you know most of those guys have survival on their mind, not engine management best practices. I'm not aware that they go through any more cylinders than anyone else does, for the amount of hours flown. :)

Obviously I do what I can when I fly their planes but I am definitely not the only one operating them.
 
Ted may know of the operation that did the engine study....but, my other Lycoming bud Tim knows of it and it related more to control of heat vs. cooling.
 
One of the harshest piston aircraft engine operating environments I've personally been around is in skydive operations, and I haven't seen an excessive amount of damaged or cracked cylinders on those engines. If anything, I'd say they enjoy a longer than normal cylinder and engine lifespan due to actually being used, at least compared to the typical low use privately owned aircraft.
I have no direct experience with piston skydive operators, but I have made an observation:

Every time the subject comes up, it seems that some people who have worked for skydive outfits report frequent cylinder problems/changes while others swear that they're changing cylinders no more frequently than a typical GA operator.

IOW, there doesn't seem to be a consensus.
 
I have no direct experience with piston skydive operators, but I have made an observation:

Every time the subject comes up, it seems that some people who have worked for skydive outfits report frequent cylinder problems/changes while others swear that they're changing cylinders no more frequently than a typical GA operator.

IOW, there doesn't seem to be a consensus.

All I can relate is personal experience and observation, which is that this specific drop zone has no ridiculous "procedures" to try and keep cylinders alive. In the time I've been around there, the only time those planes have been down is for 100 hour inspections, and no cylinders have ever been replaced. I'm not sure how many hours are being flown annually, but I'd expect 500ish per plane, maybe more.

One must remember that DZ planes are getting flown a lot more than privately owned planes so someone may perceive that there are frequent cylinder changes calendar time wise, but when hours flown is factored in it isn't excessive.

I'd also want to see some information on those excessive cylinder replacements. Since the topic I was replying to was about shock cooling, how many of those cylinders were replaced for cracking? I'd probably discard data on any cylinder that was replaced due to poor ring seal or valve leakage for this purpose.
 
Ted

Shock cooling - Do you have science behind this? When I shut the motor off temps drop quicker than what I could do flying and the motor does just fine with this.

Have you read this?
http://www.avweb.com/news/maint/182883-1.html

First off, I assume that you read my first post in detail where I explained my views on shock cooling. It is summarized as below:

Either way, the theory about shock cooling is that it will typically manifest itself not in cylinders falling off, but gradually with decreased longevity over time, cracks in the crankcase, etc.

The articles you listed look at single point CHTs on each cylinder, and don't look at the thermal map of what's going on inside the cylinder. Keep in mind that CHT numbers we see are from a single point. During certification, cylinders had CHT probes all over the cylinder to get a full mapping of temperature, and those numbers do vary quite a bit. Of course, these were still outside temperatures. The change in temperature when you shut down and everything is stationary isn't going to be as hard on an engine as when it's running simply because you don't have the temperatures and pressure changes/forces occurring every cycle.

Also, as I've stated, there's a difference between an O-360 and a TSIO-520. O-360s don't make much power and their internal pressures and temperatures are low. A TSIO-520 makes a lot of power (other than the Crusader's TSIO-520 that he specifically points out in the article you linked - that was derated to 250 HP) and is typically in an engine with poor baffling, thus resulting in running at higher temperatures.

The example of removing fins from the Crusader and running too cool is also not a particularly good one. There was more going on. First off, like I said the Crusader is a derated engine (250 HP vs. 285-335 HP for other TSIO-520s). Second off, it was the most modern baffling design that Cessna had ever created. It was really very good. The baffle designs used by Cessna in the previous TSIO-520 aircraft varied from marginal to horrendous. Baffling makes a huge difference in CHTs and oil temperatures, and anyone who has spent any time improving an engine with truly poor baffling knows this.

Many have discussed shock heating as the real concern. A gradual power application for takeoff is also good. I will normally do a gradual power application over the course of ~3 seconds.

My point regarding shock cooling has always been pretty simple: I can't say with certainty that shock cooling will hurt your engine, but I can say with certainty that reasonable practices to prevent shock cooling will not hurt your engine. I take a practical approach to this. When I can, I try to make gradual (~1"/minute) power reductions. My power reductions from takeoff to climb power and then climb to cruise power (I am now flying turbocharged engines) are done over the course of several seconds and not at the 1"/minute rate, that would be impractical. When operational considerations require me to take more significant power reductions out, I do so over the course of several seconds again, and I don't worry about it.

If you plan your descents well from a cross country, gradual power reductions won't cause any of the nonsense like gliders beating a tow plane back to the ground. I would never advocate practices like that. That's just ridiculous.
 
A recent article on the subject. I never worry about this and there is no reason to start now.

https://www.avweb.com/news/features/Shock-Cooling-Time-to-Kill-the-Myth-230134-1.html

It may have been published recently, but it's the same argument that others have been pushing for a long time. Rick's a lawyer, not someone with a technical background. In fact, I think the common trait I've observed with those who push the "Shock cooling is a myth" way of thinking is that none of them have strong technical backgrounds, and are generally trained in non-technical careers.
 
ya but....the author is a CFI....that should account for something. o_O
 
ya but....the author is a CFI....that should account for something. o_O

Generally having a CFI means that someone is teaching incorrect engine procedures that were taught to him by a CFI who knew incorrect engine procedures that were taught to him by... you get where I'm going with this.
 
read this a while ago and just re-read. One thing that jumped out at me was mention of continental recommending that they like to see CHT max temp at 380. makes sense and I will be paying more attention to this
 
read this a while ago and just re-read. One thing that jumped out at me was mention of continental recommending that they like to see CHT max temp at 380. makes sense and I will be paying more attention to this
It is particularly important in Continentals. Continental cylinders just don’t handle heat as well. I’ve seen this from experience. Keeping them below 380F is important for longevity. Lyc cylinders can take a little more heat before failure. Same for P&W.
 
It is particularly important in Continentals. Continental cylinders just don’t handle heat as well. I’ve seen this from experience. Keeping them below 380F is important for longevity. Lyc cylinders can take a little more heat before failure. Same for P&W.

It's worth noting that Lycoming sets its recommendation at 400F max continuous vs. the 380F for Continental, and also that the Lycoming CHT limits are 475-500 vs. typically 465 for Continental.

On Lycomings I aim for 380F or below, on Continentals I aim for 360F or below. LOP with proper baffles that's usually doable, other than climb in the 414 where they'll tend to creep up.
 
@Ted DuPuis what are your thoughts on spin-on oil filter conversions? Worth it or is the screen enough?

I personally did it on the 310. There's a reason why all the engines now have filters instead of screens - it's better. The filters do a better job of getting junk out of the oil, they're easier to inspect for debris when you do changes. Per the book you can extend your oil changes to 50 hour intervals with a filters (although there's still a 4 month calendar time component).

So, I think it's worth doing. I went with AirWolf and did the remote mount, but there are lots of ways to go about it.
 
Austin,

I too have a straight tail with an 0470 and I went with the F&M "pistol grip" adapter simply because I didn't like the thought of adding hoses (another potential failure point) to my oil circuit but, to each his/her own. The pistol grip adapters aren't without their downfalls either...there are repeating torque check requirements (IIRC).

There's one (C6LC-S) on ebay right now for about $50 cheaper than you can buy it for on Aircraft Spruce, etc.

https://www.ebay.com/i/142685247988?chn=ps

Whatever you decide, I agree with Ted that a filter is relatively cheap (in aviation terms) add'l protection. Not that my opinion means much! ;)
 
Austin,

I too have a straight tail with an 0470 and I went with the F&M "pistol grip" adapter simply because I didn't like the thought of adding hoses (another potential failure point) to my oil circuit but, to each his/her own. The pistol grip adapters aren't without their downfalls either...there are repeating torque check requirements (IIRC).

There's one (C6LC-S) on ebay right now for about $50 cheaper than you can buy it for on Aircraft Spruce, etc.

https://www.ebay.com/i/142685247988?chn=ps

Whatever you decide, I agree with Ted that a filter is relatively cheap (in aviation terms) add'l protection. Not that my opinion means much! ;)
Doesn't the "pistol grip" adapter have an AD against it?, I just changed one in a repair station where I work
 
I believe that AD applies to Cessna oil filter adapaters only and not the F&M adapters. But, regardless, the AD (as I recall) basically requires inspection of the torque putty at every oil change, something I do anyway.
 
btw....I googled "torque putty"....and nuth'n turned up. o_O
I believe that AD applies to Cessna oil filter adapaters only and not the F&M adapters. But, regardless, the AD (as I recall) basically requires inspection of the torque putty at every oil change, something I do anyway.
 
My Cessna 340A has two TSIO520NBs. I fill the dumps to 12 quarts before flight. After a several hour flight the level goes down a quart. If I check the level after an overnight I'll find that level is back to 12. The case lower seam allows the oil to flow into the pan through gaps among the bolts - acting like a windage tray. I typically don't climb at more than 10degrees pitch up so the high oil level doesn't exceed the case level.
 
My Cessna 340A has two TSIO520NBs. I fill the dumps to 12 quarts before flight. After a several hour flight the level goes down a quart. If I check the level after an overnight I'll find that level is back to 12. The case lower seam allows the oil to flow into the pan through gaps among the bolts - acting like a windage tray. I typically don't climb at more than 10degrees pitch up so the high oil level doesn't exceed the case level.

My c85 does the same, pretty sure it’s just all the oil all over everything takes a bit to get back down..

I will say I started using 100 weight and can’t just lift the dipstick and check anymore even after a long sit, it seems that stuff sticks to where it was maybe splashed to last, so it can appear I have more than I do. Im thinking this should mean it’s sticking to parts all the better too than the thinner multi grade I used to do...
 
This was an interesting read, I have always used multi viscosity oil, but have practiced the other things almost exactly as they are described here regarding temps and such, although have been guilty of probably taking off with the temps still a bit cooler than optimal, numerous times. As I contemplate what plane to purchase next ( hence my joining the forum ) i also get to thinking back on planes that I have owned, and generally speaking the lack of engine troubles I have had over the decades compared to some people I know. Being as I am planning to go back to basics as it is, that should help me continue with few problems since I don't plan to run a turbo charged engine in whatever I choose to buy. I want as low maintenance as possible this time around.
 
I could tell you what I do but you are gonna do what you want anyway (shrug)
My cylinders go past TBO routinely
(well, except for one IO-520D that had an appetite for rocker arm bushings - grrrr)

It's your engine and your money (and your butt if it blows up on a dark nite) Treat it with a bit of kindness.
Just because it has a certain number of minutes at WOT, that is not a requirement.
And the same for maximum cylinder head temp.
And the same for maximum EGT.
And so on.
Works for me.
 
A few things. You point out a number of times that an O-360 doesn't make much power, compared to a TSIO-520. But the TSIO-530 is 44.44% larger displacement, so if it makes 260 HP, it is the same power per cubic inch as an O-360 making 180 HP.

For climb, my POH calls for full throttle, max RPM, for a turbo engine. One issue with pulling the power back is, there is a full power enrichment on most engines, so full throttle gets a richer (cooler) mixture. Pull the throttle just a bit, and the fuel flow drops a good bit due to this.

You state 1 - 2 seconds from idle to full throttle. IMO, that is still very quick throttle movement. I am more in the camp of 4 - 5 seconds to not screw up dynamic counterweights.

If any engines were going to demonstrate shock cooler, it would be trainers. Full throttle to pattern altitude, massive power reduction, further power reduction, to idle, to full power. Again and again.

As for turbo cooldown, GAMI looked into this in their fully instrumented test aircraft and found the turbo is coolest about the time you touch down due to power reductions for landing. Also, taxi time (if at reasonable power levels) counts if you want to do a cool down. I split the difference. If I can taxi at less than 1200 RPM, I don't bother with any additional cooldown. If I go over 1200 RPM, I like to have to run at less than 1200 for 1 - 2 minutes.
 
My old flight school’s IO-360 engines made TBO every time. They were beat like red headed step children. 2000+rpm cold starts, rapid throttle changes, long periods of idle followed by full throttle go arounds (simulated emergency landings), hardly ever getting less than full rich mixture.
 
What about oil temperature? Any insight into the best temperature to run at? Hard to get mine above 170 on cold days.
 
I have heard 180 is the minimum to get rid of the excess water.

I have the same issue. Mine runs 165 or so in the cold weather.
 
I have heard 180 is the minimum to get rid of the excess water.

I have the same issue. Mine runs 165 or so in the cold weather.
TBH, like you, I've heard 180 is the temperature you need to get rid of the water. That said, I've never actually seen someone explain why that is the specific target nor point to testing data around it. The water will not boil at 165 degrees, but, it also will not boil at 180 degrees.

If you fill a glass of water and sit it on your kitchen counter it will eventually evaporate and there won't be any water left. If you stick that same water in the oven at 165 degrees it will evaporate very quickly. How much more quickly would 180 degrees be? I mean, faster, I imagine...but probably not many factors so. You could test this easily enough in your kitchen with some water and the oven.

I think, more important than whether it is 165 degrees, or 180 degrees, is that you regularly get the engine up to a reasonable operating temperature for a decent length of time. If you're not going to do that, you should pickle it and dump some oil in the cylinders.

No flight school ever has problems with water in their oil causing engines to rust. No flight school airplane has good enough instrumentation to know whether the oil is at 165 degrees or 180 degrees. Nor do flight schools worry about that sort of thing. So clearly the secret to preventing water issues has nothing to do with worrying about 165 vs 180. The secret is what all flight schools do: fly often.

So, anyhow, I wouldn't obsess too much over the 165 vs 180 (you could try to block some air to fix that) but would instead focus on just ensuring the airplane is flown regularly and for a good length of time each flight.
 
Actually water does boil at 180 degrees. At 18,000 feet. :D

It does not need to boil to evaporate. As you said, it evaporates at room temperature. It evaporates faster as the temperature goes up.
 
A few things. You point out a number of times that an O-360 doesn't make much power, compared to a TSIO-520. But the TSIO-530 is 44.44% larger displacement, so if it makes 260 HP, it is the same power per cubic inch as an O-360 making 180 HP.

There's a few holes and gaps here (and in other areas). I'll address a few of them.

I'm not sure which TSIO-520 you're talking about here and in what aircraft (I'll assume your TSIO-530 reference is a typo). The only one I'm aware of under 285 HP is the TSIO-520 in the Cessna T303 (I believe rated at 250 HP), which you shouldn't use as a basis of comparison as that had a lot of "lightweight" differences from a normal 520, and was a weaker engine as a result.

But regardless, there's more to it than simply HP/cubic inch. Turbocharged horsepower is harder on an engine than naturally aspirated horsepower. The horsepower is measured at the crankshaft (as in total output horsepower), and while turbochargers are often advertised as "free" horsepower, that's not accurate. It still takes horsepower to spin them, and that means that your total energy that needs to be created in the combustion chambers (i.e. BTUs, IOW heat) needs to go up.

You are correct that if you're looking at, say, an O-360 vs. an O-540 that has the same HP/cubic inch, overall you're looking at the same general internal forces, heat, etc. Even then there's more to it due to differences in construction, size, thermal gradients... but parallel valve naturally aspirated 360s/540s are about as bulletproof of engines as they get.

For climb, my POH calls for full throttle, max RPM, for a turbo engine. One issue with pulling the power back is, there is a full power enrichment on most engines, so full throttle gets a richer (cooler) mixture. Pull the throttle just a bit, and the fuel flow drops a good bit due to this.

Again, partly true. I'm assuming you're flying a Continental based on the above, and you're correct that Continental fuel injection systems are often not great at fueling for an appropriate climb power. This is addressed in different ways on different aircraft. It's better to run at full power and an appropriate mixture than pulled back a bit and too lean of a mixture, but if your engine is properly adjusted, this shouldn't be an issue.

Then again, if you're actually flying a 260 HP engine, I wouldn't be worried about full throttle for climb. Most TSIO-520s are 285-335 HP (depending on the aircraft and various upgrades available). Also understand that POHs aren't always written with your engine's longevity in mind.

You state 1 - 2 seconds from idle to full throttle. IMO, that is still very quick throttle movement. I am more in the camp of 4 - 5 seconds to not screw up dynamic counterweights.

Not all engines have counterweights, but either way 4-5 seconds won't hurt anything. Have at it if that's what you prefer - unless you're like the Cirrus pilot I once flew with who not only took 5 seconds to get to full throttle but did it on a short field as a rolling takeoff. He about put the plane off the end of the runway.

The real point is don't just slam it to the firewall.

Regarding the question about oil recommendation at 180F, as with everything else above, it gets more complicated. Remember that an oil temperature is the temperature at one location. Oil takes many paths through the engine, and especially in an air-cooled engine where the oil is part of the cooling, most of those places are >212F. As the oil hits those places, the water boils out. The real recommendation behind 180 is that, at that temperature, water should boil out overall as the oil gets run through the hotter parts of the engine. Your CHTs are going to be well above 212F in almost all cases, and even those are only individual point readings. I have no pictures of instrumented cylinders that we used to run at the factory, but they looked like swiss cheese with all the thermocouples.

If you want to run a simple experiment to see the difference and have an engine monitor, use a normal CHT probe (in the cylinder barrel on the bottom of the cylinder) and one under the spark plug on the same cylinder. You'll see a very noticeable difference.

Pinecone, from your posts here and regarding ABS, you seem like a younger fellow - which is great! We need more younger fellows in aviation and the automotive world. I was once one too. Now I'm old and among other things I've learned that there's the simple explanation (what is usually given to the end consumer in manuals), the slightly more complicated answer (what folks like GAMI tend to sell) and the real truth, which gets even more complicated. I’ll also bet I’ve spent more time running these engines in fully instrumented test cells than anyone else on this board and there’s still a lot I don’t know.
 
Last edited:
You mentioned the TSIO-520 at 260 HP and claiming it stressed the engine more. I was pointing out that the HP was the same per cubic inch. Yes, turbo charged stresses more, but IO-520s can make the same 260 HP. Now, a 285 HP IO-520 is more HP per cubic inch than a 180 HP O-360.

Yes, the 180 for oil temp is a rule of thumb. And yes, at various points, it will be hotter. Although I have some references that state that 165 is enough. The take away is too low of oil temp is not a good thing.

Younger????? Hmm, I got my USAF wings in 1981. And I was not fresh out of college. :D
 
I enjoyed reading this and I can tell you another side of this. I’ve seen way too many issues with people babying their engines thinking they are helping the engine to last by flying around with reduced throttle.

As somebody that works on 2-strokes another thing I’ve discovered is that a 2-stroke at idle is not getting adequate lubrication. I never idle a 2-stroke as they are meant to run and designed to be lubricated under power.

The point about warming up the engine to operating temps is a good one also. With a water cooled engine I don’t takeoff until I see the thermostat open and see a drop in water temperature.

These are really good tips. The whole point of having a run up area is having a place to warm up the engine to operating temps.

Safe flying and thanks for sharing!
 
Back
Top