But sometimes it may make sense to repair a cylinder instead of getting a new one. The weak spot of Conti cylinders are the exhaust valves and their seats.
It’s more a problem with Lycomings actually than with Continentals. The heat transport in their exhaust valve system is not up to its job. There are several theories why, the most likely one is insufficient oil flow through the valve cover. For this particular reason, the Rotax and Porsche engine have liquid cooled valve heads. You can replace the valve and valve guide without much effort.
My shop has developed a tool that allows them to hone the valves with the cylinder installed on the engine.
Not much to develop, that is a standard tool which I have in my hangar. I’ve had my engine break down in Africa due to a stuck exhaust valve and had to fabricate a similar tool to get it going again. During this episode, I learned a great deal about Lycoming valves and cylinders…
There is a tool from Lycoming and a much better one called Valve Wizard:
Bosco,
is that more a feeling, or do you have any data about the life span of Continental cylinders? Until I ruin my first set (;-)) I tend to think that most cases are really pilot induced. This (not representative!) experience comes mostly from the training and PPL check flights i did with private pilots. There’s really very little understanding about engines in the general pilots population. I remember the times when I still rented my Warrior and the fuel consumption was always +40 liters because so many pilots did not even bother to LEAN the engine … (“my flight instructor said that the engine will quit if I move the red knob”, “I never lean below 5000 feet”, “leaning destroys the engine”, “fuel is cheap, engines are expensive”… that kind of gossip, you know it too)
My personal feeling is that you might get a bad cylinder however well you treat the engine, but that it’s much, much less likely to happen. Check the hours many COPA pilots have on their 1st engines!
Yes, but just the same there are many many examples of people on COPA who are very knowledge and cautious with their engines and still have to get cylinder work done at between 500-1000 hours. At the same time, there are those who go to TBO (at least non-turbos) without any intermediate cylinder work. It’s impossible to discern a pattern there.
Then if you go to the turbocharged aircraft and look at controller.com and so on, most have had some work. This seems to be equally true for Turbos Bonanzas, Turbo Mooney, Turbo 210s and Malibus. I guess the vast majority of owners of such aircraft is rather knowledgeable and doing the best they can to treat their engines well.
Until I ruin my first set (;-)) I tend to think that most cases are really pilot induced.
Yes and no. Pilot induced is one thing. Operator induced is another.
A few questions:
Do you fly it >200 hours a year?
Do you fly at least every two weeks, even in winter?
Do you use pre-heat in the winter?
Is your hangar heated?
Do you vent the oil filler neck after every flight?
Do you change oil at 30 hour intervals?
Need I continue? 
I know, it is not practical for us to do these things. It is just to show that you and me we are prime candidates for needing engine work sooner or later. Go on and live with it. There are much more expensive things that can happen with our aircraft than a bit of engine work (depends on what it is, of course).
This discussion makes me scary. I have a Lycoming TIO-540-AK1A with turbocharger. Equipped with EDM700. No heated hangar. Use prea-heat every time below 4° C. OAT. I fly only 80 hours a year, regulary minimum every four weeks also in winter time, Oil change every 50 hours. I operate the plane conservative which means to stay always at low temperatures, cruise flight 55-65 percent, moving the throttle very slowly. Engine time is actally 600 hours, so far no problems.
Is it really important to change oil every 30 hours ? What is the meaning of venting the oil filler neck ? Have never heard about. Does it make sense to cool the engine a bit extra by opening the cowl flaps in cruise ? Does Cam Guard really help ? What else can I do to prevent from any cracks ?
Do you vent the oil filler neck after every flight?
Not heard of that one before. I would have thought that the breather pipe, which comes out of the engine at the top
and at about the same level as the oil filler hole, would provide an adequate vent. The slightest pressure differential will vent out of that pipe.
How “open” the breather is to the main crankcase cavity is a good question. I have never sees a picture of the back of the engine, with the accessory gearbox removed. There must be some open holes in there, otherwise the breather would not work at all. This however suggests there are no huge holes
Camguard does reduce the metal wear – see the Camguard threads here.
Well, obviously what you vent is the crankcase, and you do that by opening the oil filler cap after flight for at least half an hour. Many “serious” COPAns do that in order to vent humidity out of the engine and avoid condensation. Don’t know if it really helps a lot. But it’s part of a set of operator techniques (independent from flying techniques) that people advocate for getting good engine longeivity. And yes, I think these are more important than the piloting techniques (I mean, it doesn’t need mentioning that pilots shouldn’t overheat engines, slam the throttle, etc. and most owner pilots don’t do that).
However, I was more referring to the “internal” health of the engine, not cylinder cracks. While it’s a good habit to keep temperature under control, most cylinder cracks happen fundamentally due to manufacturing defects, I believe.
Many “serious” COPAns do that in order to vent humidity out of the engine and avoid condensation. Don’t know if it really helps a lot.
It certainly does help because you can see the vapor coming out of it. I do it, too but you have to be careful to not forget to screw on the oil filler cap or you’ll be in for a very nasty surprise on takeoff.
most cylinder cracks happen fundamentally due to manufacturing defects
It’s mostly a Continental issue and due to the design of the barrel/head joint. It just seems they are not made to last TBO on high power Contis. Some people might never fly their airplane fast and thus get a longer life but that means they probably bought the wrong aircraft. The best example of this Conti weakness is the Cessna P210 because you have to fly it a lot at 100% and 75%. There, cylinders very rarely last longer than 900h. That is the TSIO-520, the TSIO-550 as used in the Cirrus SR22T appears to be a bit more durable.
I think leaving the filler open is operationally not possible for many people (myself included) who have to leave the plane outside (potentially in the rain) after flying. If I had my own hangar and was always able to move the plane into it after a flight, I would try this.
However if you have your own hangar, or a similarly cosy arrangement in a shared hangar, then you can have a mains powered dry air generator which you simply stick up the exhaust pipe and that will dry out the engine completely. I started building such a thing. It is just a device containing a 0.5kg silica gel bag (of the kind I leave in the cockpit after every flight, and that works) and a tiny battery powered fan, and a battery, and it would clip onto the exhaust pipe. I never finished building it because it would get stolen between leaving the plane, and the plane going back into the hangar anything up to a day or (rarely) two days later.
But if you have your own hangar, the world is your oyster as they say 
You can pay a freelance engineer to do your Annuals and save a few k every time. Which is why hangars where maintenance is allowed are scarce – for airfield-political reasons. This is one of the advantages of a “farm strip”, of course…
I get the occasional spike on iron in the oil analysis and that is prob99 a bit of cylinder corrosion – despite flying every week and using Camguard. And changing the oil every 20-30hrs.
most cylinder cracks happen fundamentally due to manufacturing defects
That may be with Contis but I think you can crack any Lyco cylinder (maybe not on the O200) if you go up to 500F and then close the throttle. So I am really careful with that. Sudden power reductions are OK if the CHT is below say 300F and indeed are unavoidable when landing
Sorry, but some of this sounds like “homeopathy” to my ears.
Of course I cannot prove it (just like nobody can prove that the above makes sense, but in my view:
- Changing oil every 30 hours is a waste of oil, and money.
- Opening the oil filler cap after every flight might have some theoretical effect but I still don’t do it
Of course, the more you fly, the better. To FLY REGULARLY is the most important point for me. And of course there’s less stress on the engine if you pre-heat it. But I can’t and don’t do it.
While I also cannot prove that there’s a “pattern”, I am still “convinced” (whatever that means :-)) that engines are actively ruined. Let’s see if I ruin mine …
PS: If we agree that LOP operation and flying regularly is GOOD for the IO-550, the that’S already a pattern, right? Otherwise these tipps make no sense.
However if you have your own hangar, or a similarly cosy arrangement in a shared hangar, then you can have a mains powered dry air generator which you simply stick up the exhaust pipe and that will dry out the engine completely.
That is one of my upcoming projects. I am going model it after this engine dehydrator. What I don’t know yet is whether the end of the oil dipstick tube is above or below the oil level on my bird. If it’s below, I will manufacture an adapter for the oil filler neck. I don’t think the exhaust would help much because all you are going to do is push air into the cylinder that happens to have the exhaust valve opened. There is no connection to the crankcase which is the source of humidity as it contains the oil.
