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Mixture control…

Asked by: 4534 views General Aviation, Student Pilot

Above 3,000 ft...I am supposed to adjust the mixture.  I lean the mixture, and the EGT needle drops.  I climb to 6,000...and the needle has moved back closer to peak EGT.  But THIS TIME, what If I ENRICHED the mixture?  The needle would STILL drop, no?

So, the EGT needle would also move in the same direction (i.e.- drop)...however, we would be running RICH OF PEAK, right? 

If my planned cruise was 9,500...I wouldn't wait to adjust the mixture UNTIL then, right?  I'd adjust every 3,000 feet?

I assume the richer the mixture it is, the COOLER the exhaust gas temp.

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2 Answers



  1. Jason Schappert on Oct 31, 2010

    Correct adjust the mixture as needed during the climb.
     
    You should be getting a rise on you EGT when you lean. I don’t really lean to peak but pretty darn close
     
    Jason

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  2. Kent Shook on Oct 31, 2010

    If you stay at one altitude and slowly lean from full rich, the EGT should rise, and then eventually fall. So there isn’t a one-way relationship between mixture and EGT.

    At full rich mixture, you should be much richer than peak EGT, and thus cooler.

    So, when you first lean from full rich above 3,000 feet, the EGT should *rise*, not drop.

    As you continue your climb to 6,000 feet, if you don’t move the mixture knob, your mixture will be getting richer and richer due to the thinning air as you climb, so the EGT should drop as you climb (and you’re getting further from peak EGT, not closer, unless you’re already lean of peak). And yes, if you further enriched the mixture via the knob, the EGT would drop more.

    Yes, you want to lean during the climb. Take note of your EGT as you’re climbing through pattern altitude, and then slowly lean to maintain that same EGT during the climb.

    “The richer the mixture, the cooler the EGT” is only true when rich of peak. After you pass the peak, the leaner you go the cooler the EGT.

    Generally, most training airplanes are operated rich of peak. There’s a lot of debate in the pilot community about where to best run an engine, but most carbureted engines do not run smoothly lean of peak and many fuel injected engines don’t either. So, when training, just be aware that if the EGT gets cooler as you’re leaning, you are lean of peak and probably want to enrichen the mixture slightly.

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