I would not know much about engine management had I not spent a significant amount of time trawling the net, searching for aviation related information, finding AvWeb and been passionate enough to actually read all of its contents leading me to yet other contents etc. Most people do not do that. They have wives, kids, in-laws and all sorts of other occupations that are more important. Those of us who spend time reading and contributing to EuroGA are clearly in the top 10% (or less) most passionate and (probably) knowledgeable of light aircraft pilots.
Then you have all of the others who are content with the information passed on to them by their instructors (what_next and Cobalt excluded 
), mechanics or fellow pilots who got the information from the same source, telling them that fuel is cheap, cylinders are expensive and EGTs above 1450°F burn valves.
PS: And please forgive my slightly provocatively naïve post #22. At least it created some debate And I did get the answers I expected.
Rwy20 wrote:
This just happened again last weekend in a French club where for checking out on a C182, the clear announcement was: Don’t lean at all below FL080. If I’m told that by the owner, I surely respect it, especially when renting wet. Even though it hurts my pilot pride a bit.
Unless it has a G1000 (or JPI 700), you could choose to ignore it.
boscomantico wrote:
Please educate me: where does this photo show any signs of a “burned valve”?
The signature of a “burnt” valve is the assymetric colored circles that is caused by the tempature on the exhuast valve.
When all is ok, the pinkish coloured circle will be a near perfect circle as in the green line.
In the photo, we can distinguish the hot gases are most probably leaking and thus causing the assymetrical pinkish lines towards the 9 o’clock area of the valve.
Removing the valve would probably reveal more errosion damage caused by hot exhaust gases leaking from the area marked with the red line.
@Aviathor thanks for posting CHT. I could not see anything there to support my theory that maybe a spark plug had failed.
Very interesting photo!
Thanks
Michael wrote:
n the photo, we can distinguish the hot gases are most probably leaking and thus causing the assymetrical pinkish lines towards the 9 o’clock area of the valve.
That is what I thought too, but wasn’t quite sure. It does not seem obvious on this particular valve. It is a lot more obvious on those on “Anatomy of a valve failure” as well as those presented in Mike Busch’s videos. This valve must have been in the early stages of failing. I flew this airplane for 20 hours straight prior to the stuck valve episode, and the engine data showed no signs whatsoever of an incipient valve failure.
There was no morning sickness either. This engine always started perfectly on the first blades.
In any event, if the valve got stuck in the guide, it was not due to operating the engine at peak EGT, but operating the engine too rich, particularly on the ground, creating deposits on the valve stem.
Aviathor wrote:
This valve must have been in the early stages of failing.
Correct.
Aviathor wrote:
if the valve got stuck in the guide, it was not due to operating the engine at peak EGT, but operating the engine too rich, particularly on the ground, creating deposits on the valve stem.
Could be, but then again there’s no direct cause vs affect with Lycoming’s valve guide issues.
Consider that this whole valve guide drama only started about 15 years ago just when LOP ops was really starting to gain traction.
Makes one wonder why there were no problems for the 50 years preceeding.
But that doesn’t make much sense either. Before LOP really started in flat aircraft engines, everybody was flying 50 degrees ROP (the worst possible place for CHT), some used 75 degrees ROP and some used 100 degrees ROP. (Actually, most people did not really know where their 4/6 cylinders operated, since they didn’t have the instrumentation to do that).
Now when you fly 50 degrees LOP, your EGTs will be between 0 and 50 degrees hotter than before (with noticeably lower CHTs by the way). And you think these 0 to 50 degrees more on the EGT suddenly make valve guides go bad?
Somebody needs to do some testing in which the exhaust valve sealing surface temperature is measured, taking the data out through the valve stem. Measuring EGT and CHT is just a way of estimating the temperature of the valve itself as it alternates between thermal contact with the valve seat and immersion in flowing exhaust gas.
Silvaire wrote:
Somebody needs to do some testing in which the exhaust valve sealing surface temperature is measured, taking the data out through the valve stem.
Done by NACA in 1942 already.
