When to lean mixture?

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07-26-2007 | 07:37 AM

#11

mcartier713

Blue Light Special

Joined: Jan 2007

Posts: 637

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From: Learjet 45 & G-IV

Quote:

Originally Posted by rickair7777

Unless the POH says otherwise you should lean for taxi at all altitudes...this will keep the plugs from fouling in those engines that are prone to that. A long hold idling at full rich can foul them badly enough that a mechanic will have to remove and clean them.

haha rick is exactly right. this happened to us yesterday. I flew safety pilot for a kid yesterday and we went up to 5500 without leaning it out. When we got back on the ground, WOW the mags didn't like us. Thankfully we were with a mechanic and he got the spark plugs clean for us.

07-26-2007 | 11:48 AM

#12

Ewfflyer

Flying Farmer

Joined: Jul 2006

Posts: 3,160

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From: Turbo-props' and John Deere's

I flight instructed in a 172 that if you didn't lean it on taxi, it'd load up and you'd have to run for over a minute before you'd clean the plugs up. It all depends airplane to airplane. Now if you're in fuel injected, I recommend it when you go to 75%(Especially the ones that have the fuel-flow's with the recommended setting on them).

Now when it came to students on X-C work(really the only time you got high and steady enough), I said to do it once you've leveled off and established the pre-determined cruise power setting. Then I showed them how to fine tune it from there.

07-26-2007 | 12:24 PM

#13

74plb

Gets Weekends Off

Joined: Mar 2006

Posts: 215

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Quote:

Originally Posted by flyboy275

i fly Cherokee's and ever since ive started leaning on taxi, ive been having rougher run-ups when i check the magnetos......i end up smoothing it out with the mixture, but wasn't this the reason i leaned for taxi in the first place?

Just to clarify, do you do your mag check with the mixture leaned out? When I owned my 0320 I'd lean it out for taxi and always go full rich for the mag-check and Take-off under normal conditions. Then once in level cruise I'd lean it out.
100LL is very well known for fouling the plugs @idle power as you know.