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Increased fuel consumption on descent

Asked by: 813 views Flight Instructor, General Aviation

Piper Dakota POH, cruise flight fuel consumption is listed at approx. 13 gph; in descent, 15 gph is listed. Why increased fuel consumption when going "downhill"?

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1 Answers

  1. Kris Kortokrax on May 10, 2016

    The “Speed Power – leaned to peak EGT” chart shows 12.65 gph at 75% power, which is shown as 21.5″ MP and 2400 RPM.

    The “Fuel, Time, Distance to descend” chart shows 1.5 gallons and 6 minutes to descend 6000′. That would give 15 gph. RPM is specified as 2400 and throttle as required.

    I am assuming that this is how you derived your numbers, since there is no fuel consumption chart for a descent.

    I would say that the reason for the difference is that prior to beginning the descent, the checklist directs you to move the mixture control to full rich.

    You can see from the “Speed Power – leaned to 50 degrees rich of peak EGT” chart that your fuel consumption increases by 1 gph. It would not be unreasonable to infer that it would increase 2 gph by going to full rich.

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