We should add that as a feature in autorouter: require maintenance shop in glide distance…
Maybe route Straubing, Kassel, Antwerp for Piper support…
Achimha – a perfectly acceptable situation to self-quote! Thank you for your help.
Jason – no flight test yet. The compression on cylinder 2 is strong; it’s a bit low on cylinder 4 and I’ve asked them to check it while they’re at it, but all the rest looks fine. I’m planning to go back to Belgrade this weekend to pick it up. I’ll start with some tests flights, and if the current wind situation persists, will probably go around the alps via the east as it will be faster than going straight anyway.
Patrick, has the solution been verified in flight? Did they do a compression check?
It sounds like a clogged injector nozzle to me.
Sometimes one must be allowed to quote oneself 
Glad it turned out to be the least expensive of all options. You might want to study the technique how to clean it, it can happen again.
So in the end it seemed like a clogged injector; I ferried the plane with a rich mixture for a short hop to Belgrade where they have better facilities, and they have indeed found the cyl2 injector to be partially obstructed. I’m glad it’s something so easy to fix, and I now know how to identify and neutralise the issue in flight (again increase the mixture, and potentially reduce the power and descend).
Thank you for all the pointers!
edited for spelling.
Do a google on
lycoming the old rope trick
and you will find loads of hits.
Whether this is your issue I have no idea. For example my engine, IO540-C4D5D, doesn’t have the sticking valve problem, due to a different valve guide design (or coating?). Lyco addressed this many years ago but a lot of the old cylinders are still out there.
It was rough (more precisely some kind of banging/rattling sound, like something was loose and hitting the cowling) for the first 30 seconds or so, then not.
It would be three probes: EGT and CHT on the JPI, and the original CHT monitor (which has a probe per cylinder). Before I noticed that this last on had gone very low as well, I thought the JpI EGT probe had gone loose, and was rattling. But then it (JPI EGT) would not indicate hot, I’d think, and CHT cold.
Achimha,
thank you for your post. That’s very interesting. If you can point me to a place I can read more about this technique, that would be great please. I haven’t notice any particular engine roughness on first starts, but maybe a close study of the JpI files will tell me I missed something there.
Denopa, your post #36 doesn’t sound much like the engine actually went rough. Sure enough, if that cylinder didn’t produce any power (or even if it produced reduced power somehow), the vibration would have been very noticable…
Are you sure it wasn’t just an indication problem? Two probes going bad at the same time would be rare, but not at all impossible. The airspeed drop could have been a downdraught (happens to me often when over the Balkans).
I’m running ROP (in the Mirage, it’s a lottery wether you can or not, and my engine doesn’t like it).
ROP contributes to getting a stuck exhaust valve. It’s a Lycoming disease.
Not something I’ll be able to fix here I’m afraid!!!
Don’t say that, the very same was fixed in Africa with just a travelling toolset and a lot of McGyver… A shop will probably suggest to send somebody with a new cylinder and bolt that on but that’s usually not the right solution. A valve guide can be reamed without removing the cylinder, with just a few tools and a technique most shops don’t know about. I’ve practised that technique a lot after I encountered the problem last year. If you think it is a stuck valve, remove the rocker cover from the cylinder, turn the prop and observe if the valve (the one on the right) travels freely.
PS: A stuck valve announced itself by the so called “morning sickness”. This is engine roughness on the first cold start of the day which goes away after 20-60 seconds. The cylinders affected would not show EGT during that. If you never experienced this, then it is most likely not a stuck valve.
