Lean in cruise

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acroshaw
Airman Basic
Posts: 2
Joined: 17 Jul 2015, 03:26

Lean in cruise

Post by acroshaw »

Apologies if this has been asked before , but my memory sucks ( I did have brain surgery recently so I have a great excuse !) . In climb I am leaning for max rpm, in the cruise I think I have to lean for 75% of max egt on the rich side , however I am finding that I need to lean less in cruise than in the climb , is this due to the higher throttle setting in the climb ? I was surprised that I needed so little leaning even at 10500 ( although I realise that default fsx leaning is woefully wrong ) .

Alfredson007
Technical Sergeant
Posts: 540
Joined: 16 Feb 2011, 07:42
Location: Finland

Re: Lean in cruise

Post by Alfredson007 »

You should only lean when the engine is producing 75% or less power, the exact amount of power developed can be determined by using the power chart on the manual.

Keep it full rich up until around 5000ft or so when full thottle, then you can lean. At cruise lean until egt gauge rises no more, then enrich for two notches, one notch in the egt gauge stands for 25F.

If you cruise below 5000ft you can and should lean in cruise, just make sure you are producing 75% or less power.

You can also lean by ear, just listen carefully, when the engine is getting rough, then enrichen the mixture until it sounds good.

Wobbles
Airman
Posts: 11
Joined: 05 Jul 2015, 02:37

Re: Lean in cruise

Post by Wobbles »

The POH recommends leaning only after 3000ft during a climb, even then I would be quite cautious about it but yes leaning for max RPM.

Once in cruise with a maximum continuous power @ 75% the recommended lean is 50* Rich of peak while for best economy just lean for peak EGT.
Best power can be achieved at 100* rich of peak or 4 notches on the EGT gauge.

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