Out to the field, first flight for the first time it just worked. I could set the engine anyplace I wanted and it just held the setting through the whole flight. I have also done this on my Ringmaster that was acting up at times just moved the line above the fuse to get it in the free airstream, worked great. So if you are having inconsistent runs try this old fix.
That's not a "fix", so much as adding an additional feedback loop that *sometimes* limits the effect to negligible. Runs faster, gets ram air, slightly more feed pressure, and richens up the mixture. It's very sensitive to that if there are consequential fuel flow restrictions - it's one of the biggest differences we found between the PA and the RO-Jett 61, The PA as we ran it was very sensitive to fuel pressure changes, ram air has a very large effect.
The root cause is old fuel residue and after-run oil, if used, burning off. It doesn't happen, for instance, when you do multiple sessions a day, and not if you leave the airplane in a warm place overnight, the next morning, this effect doesn't happen. Leave it a week, and it does.
The after-run oil I used had a distinctive smell to it, and sometimes, it took almost the entire first flight to burn it all off, you could smell it. I think it is as simple as that, it takes a while to clean itself out.
Note that if you are not super-careful, there's another effect in play. The last time you flew it was typically the afternoon, where its nice and warm. The next time is the morning, where it's not as hot. You should expect to have to open the needle slightly when it's cooler, and then have it go back later. It would be easy to confuse the two effects.
Brett
Topic: Lean first minute then settles only on first flight? (Read 1708 times)
