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mag check on O-360A

Asked by: 2552 views Aircraft Systems

On Mag check with Lycoming O360-A Should Mixture Be Fully Rich Or Lean

On 1800 RPM With Fully rich mixture we get 200 drop on left mag But when we lean

the Mixture We have no Problem

Thanks in advance Fred.

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1 Answers



  1. Mark Kolber on Jul 10, 2017

    Hard to answer with certainty based on the information you gave, but:

    If your density altitude is such that you would lean for takeoff, the mixture should be equally lean for the runup.

    If your plugs were a little fouled due to an excessively rich mixture during taxi, it would be no surprise to have a mag check with an excessive drop clear after leaning the mixture and letting it run for a while.

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