lean for taxi ?

[tathepilot]

Whats the deal with this.
Some people do it. Is it necessary in ny? 82msl

 

[midlifeflyer]

I flew with a CE-182 owner in Southern California (same low altitudes) who always leans aggressively for taxi. He told me that he's the =only= one of his friends who has =never= had fouled plugs.

 

[Vik]

I dont know about New York, but I'm in SoCal, and I do it on a Piper PA-30 Twin Commanche. If I don't do it, there is a chance I'll have some fouled plugs by the time I get to the runup or leave the runup.

I operate out of Chino and the taxi to takeoff can sometimes be very long. I also operate out of John Wayne and it could be 20 mins between engine-start and actually taking off.

Actually, it makes no difference if its a PA-30 or a C-152. I've always leaned for taxi and been taught to lean for taxi.

Whats the deal with this.
Some people do it. Is it necessary in ny? 82msl

 

[flyer172r]

Usually in the summer I lean during taxi, but not during the winter.

 

[redd]

If your idle mixture is set properly, there is no need to lean. Idle mixture should be adjusted seasonally; several times a year.

Idle mixture must be adjusted by a qualified mechanic; it's not a pilot function. If you're loading up on the way to the runway, you are in need of maintenance.

Adjusting the mixture at idle has no effect until right before cutoff, as you're not working off your main jet; you're working off your idle jet, which has an entirely different mixture control.

 

[saviboy]

In mys school (FLL in florida), evryone had to lean the aircraft fleet on any flight.

I just asked to a local mechanic and he recommended to lean the mixture on the ground and at any altitude.

 

[uwochris]

I always lean the mixture "brutally" while taxiing. I researched this topic not too long ago (read many of the Deakin articles on this topic over on avweb), and after consulting the POH for the a/c I fly, there does not appear to be anything wrong with leaning the mixture while taxiing.

Some people may argue that you will run the temps up too high, but at such a low power setting, you can lean it as much as you want without causing heat damage.

 

[avbug]

Chris,

"Heat damage" isn't the biggest threat with leaning. Detonation is. Damage from excessive heat can occur under many circumstances, and often occurs when operating at other than peak (stochiometric) mixture settings.

Leaning during taxi won't hurt anything, but if your idle mixture is adjusted properly, there is no need to do so. As Redd indicated above, with your throttle closed, you're working off your idle jet, not your main jet, and this means that the idle mixture needs adjusting.

You don't control, and cannot adjust, the idle mixture from the cockpit. That is a maintenance function; it's something your mechanic must do. It should be done any time the airplane changes it's base location to one of a different climate or elevation. With seasonal changes in average density altitude, the idle mixture should be periodically readjusted to compensate.

When adjusting your mixture control in the cockpit, you're adjusting the fuel flow into the main jet of the carburetor. Not until the final travel of the mixture control, right before cutoff, do you have any impact at all on the idle mixture, and only then strictly because you're rotating the mixture lever to the cutoff position. it's a rough approximation at best.

The fact that your engine will load up on taxi indicates only that the aircraft is not being correctly maintained, and that adequate maintenance has not been performed in the upkeep and adjustment of your carburetor and/or fuel control.

Will leaning agressively during taxi hurt anything? Of course not. You can operate at "peak" all you want at reduced power settings without much fear of any kind of damage to the engine. Generally below 75% power you're not in any danger of detonation, or any thermal damage from a mixture setting; certainly at idle you're not going to harm a thing.

The best reason for putting an agressive lean position on the mixture control during taxi is not to prevent fouling of plugs (again, this should have been done by your mechanic by properly adjusting the idle mixture setting, and you can't control that), but to prevent you from taking off with the mixture in anything but the appropriate takeoff setting. If you're leaned back agressively, then the engine is going to start bucking and banging when you power up, if you've forgotten to set it. It's a safegaurd against pushing takeoff power settings with an improperly set mixture, because at highly leaned settings, you won't be able to push the power up without the engine talking to you, loudly and clear.

 

[tinman]

Above what RPM are you usually out of the idle setting?

 

[Vik]

avbug,

I only get fouling on my twin once in awhile, and you are right in that at idle, it doesn't make a difference. I have a digital fuel flow gauge in the plane and adjusting the mixture during taxi doesn't change the fuel flow.

I get fouling once in awhile and its probably under certain weather conditions in which the idle setting is too rich. Thats all I can think of. So I've gotten in the habit of leaning the mixture for taxi .. but again, if the fuel flow isn't changing, am I really even leaning it?

Chris,

"Heat damage" isn't the biggest threat with leaning. Detonation is. Damage from excessive heat can occur under many circumstances, and often occurs when operating at other than peak (stochiometric) mixture settings.

Leaning during taxi won't hurt anything, but if your idle mixture is adjusted properly, there is no need to do so. As Redd indicated above, with your throttle closed, you're working off your idle jet, not your main jet, and this means that the idle mixture needs adjusting.

You don't control, and cannot adjust, the idle mixture from the cockpit. That is a maintenance function; it's something your mechanic must do. It should be done any time the airplane changes it's base location to one of a different climate or elevation. With seasonal changes in average density altitude, the idle mixture should be periodically readjusted to compensate.

When adjusting your mixture control in the cockpit, you're adjusting the fuel flow into the main jet of the carburetor. Not until the final travel of the mixture control, right before cutoff, do you have any impact at all on the idle mixture, and only then strictly because you're rotating the mixture lever to the cutoff position. it's a rough approximation at best.

The fact that your engine will load up on taxi indicates only that the aircraft is not being correctly maintained, and that adequate maintenance has not been performed in the upkeep and adjustment of your carburetor and/or fuel control.

Will leaning agressively during taxi hurt anything? Of course not. You can operate at "peak" all you want at reduced power settings without much fear of any kind of damage to the engine. Generally below 75% power you're not in any danger of detonation, or any thermal damage from a mixture setting; certainly at idle you're not going to harm a thing.

The best reason for putting an agressive lean position on the mixture control during taxi is not to prevent fouling of plugs (again, this should have been done by your mechanic by properly adjusting the idle mixture setting, and you can't control that), but to prevent you from taking off with the mixture in anything but the appropriate takeoff setting. If you're leaned back agressively, then the engine is going to start bucking and banging when you power up, if you've forgotten to set it. It's a safegaurd against pushing takeoff power settings with an improperly set mixture, because at highly leaned settings, you won't be able to push the power up without the engine talking to you, loudly and clear.