Leaning for density altitude

A

azaviator08

New Member
I was always taught to lean for density altitude when it is about 3,000. I have read somewhere that it should happen anytime the density altitude is 5,000. Anyone have any insight on this? I cannot find it written anywhere in an FAA book. Does anyone know a book or reference that talks about this subject?
 
Sparky Imeson's (R.I.P.) Mountain Flying Bible (was gonna add a link, but Slushie doesn't carry it...doh!) talks about it at length and there are several articles on the subject at AvWeb.com.

I've heard it argued that you should lean all the time, even at sea level.
 
Arrow (1969) POH says always lean above 5000ft and at pilots discretion below that (or something to that effect).
 
For the Cesna 152 the POH says to lean for cruise at any altitude, as long as you are below 75% power. Lean to best power for climb above 3000.
 
aloft said:
I've heard it argued that you should lean all the time, even at sea level.
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I'm going off the top of my head here but I think I remember the C172 checklist saying 3 turns after engine start and lean for max power before t/o. Max power isn't necessarily full rich. Hot summer days when DA was ~3000 we actually leaned a little bit before taking off.
 
The mixture control should always be ensure the engine runs smoothly. I have flown planes, seems to be ones with larger engines, that will run rough at seeminly low density altitudes. Some people miss this, thinking if you are below 3000 ft pressure altitude it can be ignored.
 
The AFM will normally have a specific procedure for leaning. Piper recommends leaning to peak EGT, then +100 for best power. Cessna is the same, but +50. I believe both are recommended above 3,000 feet, but I'm not 100% on that.
 
deadringer86 said:
The AFM will normally have a specific procedure for leaning. Piper recommends leaning to peak EGT, then +100 for best power. Cessna is the same, but +50. I believe both are recommended above 3,000 feet, but I'm not 100% on that.
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Yep if I recall the climb checklist says Lean Above 3,000...MSL or DA :) ?
 
If you're one of my students, you leave it full rich all the time, and then when in the run-up you are questioned about a rough-running magneto, you explain that "the plane is probably due for maintenance." :laff:
 
We had a debate at our school after burning through a cylinder in only 50 - 100 hours or so. (It was ridiculous). Anyways, our mechanic brought it up with his guy at Lycoming (We fly 172R + S) and they came to the conclusion leave rich on the ground and on take off and once you climb through 3,000msl, you can begin to lean at pilots discretion. On those summer days when DA is above 3,000, lean on the ground. Of course, that's just our school.
 
1. Lean for taxi. Lean almost to the point where the engine fails- that way if you forget about it you'll remember as you add take off power. You won't hurt anything since you are (should) be well below 65-75% power, even at sea level. Lean prior to taxi on the ramp, and lean after landing.
2. I teach pilots how to lean for take off (per the POH), but then I also show them where to set the mixture. If it's a training airplane it is rough on an engine doing the run ups several times a day. On my airplane I actually have the mixture painted at the mark where I want students to set it so I'm not trying to show them from the back seat.
3. If maximum power is required for takeoff, such as a short field, I do a full power mixture setting.
4. Also, follow the POH.
 
JulietBravo said:
We had a debate at our school after burning through a cylinder in only 50 - 100 hours or so. (It was ridiculous). Anyways, our mechanic brought it up with his guy at Lycoming (We fly 172R + S) and they came to the conclusion leave rich on the ground and on take off and once you climb through 3,000msl, you can begin to lean at pilots discretion. On those summer days when DA is above 3,000, lean on the ground. Of course, that's just our school.
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By "burning through", what do you mean? Depending on the actual point of failure on the cylinder, this could have a lot or nothing at all to do with mixture management.
 
Blackhawk said:
1. Lean for taxi. Lean almost to the point where the engine fails- that way if you forget about it you'll remember as you add take off power. You won't hurt anything since you are (should) be well below 65-75% power, even at sea level. Lean prior to taxi on the ramp, and lean after landing.
2. I teach pilots how to lean for take off (per the POH), but then I also show them where to set the mixture. If it's a training airplane it is rough on an engine doing the run ups several times a day. On my airplane I actually have the mixture painted at the mark where I want students to set it so I'm not trying to show them from the back seat.
3. If maximum power is required for takeoff, such as a short field, I do a full power mixture setting.
4. Also, follow the POH.
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Good plan. On my Swift, the HIO-360 will foul up if I do not lean right after start. Per John Deakin's and George Braly's work, I go lean of peak en route.
 
Orange Anchor said:
Good plan. On my Swift, the HIO-360 will foul up if I do not lean right after start. Per John Deakin's and George Braly's work, I go lean of peak en route.
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My AEIO-360 is the same way. If I don't lean right after start and after landing it fouls up.
Your Swift has an HIO-360???
 
Blackhawk said:
My AEIO-360 is the same way. If I don't lean right after start and after landing it fouls up.
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I met a guy in the LA area with a 182. He told me he's the only one of his friends who leans for taxi at sea level. He's also the only one of his friends that has never had fouled plugs.
 
My weird observation:

Both my flight schools had relatively the same Make/Models on the line. The two field elevations are only 300ft different.

Yet at my current flight school, we hardly ever get fowled plugs from start up to run-up.
It is like pulling teeth here to get people to lean for taxi, because in there eyes it doesn't change anything.

Any ideas why our plugs don't get fowled? Is it something to do with MX?
 
Blackhawk said:
My AEIO-360 is the same way. If I don't lean right after start and after landing it fouls up.
Your Swift has an HIO-360???
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Yes.. the engine came out of a helicopter. It is rated at 210hp but that's at about 3100 rpms which I can't pull so officially it is 180hp. It will do 1500-1800fpm on T/O. Leaned out I file 130Kt true at 8-9gph.
 
Douglas said:
My weird observation:

Both my flight schools had relatively the same Make/Models on the line. The two field elevations are only 300ft different.

Yet at my current flight school, we hardly ever get fowled plugs from start up to run-up.
It is like pulling teeth here to get people to lean for taxi, because in there eyes it doesn't change anything.

Any ideas why our plugs don't get fowled? Is it something to do with MX?
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Yeah. They probably have the idle mixture set different.
 
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