High altitude (for a 172 anyway)leaning procedures
- Thread starter Bryan
- Start date
pscraig
Well-Known Member
Check the POH carefully, many engines require full rich above a certain power setting (75% is common) for engine cooling during the climb. During cruise I usually lean the mixture until I get some roughness, then enrichen the mixture a little.
I usually run engines a bit on the rich side. It's much cheaper to burn a few more gallons of fuel over time than replace cylinder heads and pistons from overzealous leaning.
On descent I usually go full rich.
I usually run engines a bit on the rich side. It's much cheaper to burn a few more gallons of fuel over time than replace cylinder heads and pistons from overzealous leaning.
On descent I usually go full rich.
dgRoot
Well-Known Member
Here in Colorado we do our fair share of leaning. As a rule of thumb I usually lean about 1/2 turn per 1000 feet as I assend. Once I reach cruise, I lean mixture slowly untill I get a drop in RPM or a little roughness.. Then about 3 quick 3/4 turns toward rich.
Remember, this is only rule-of-thumb stuff. There is no replacement for the POH. I've flown 172s that have had
different mixture sensativities.
-Dave
Remember, this is only rule-of-thumb stuff. There is no replacement for the POH. I've flown 172s that have had
different mixture sensativities.
-Dave
MidlifeFlyer
Well-Known Member
Re: High altitude (for a 172 anyway)leaning proced
The CFIs around here generally teach releaning every 2000' during the climb.
The CFIs around here generally teach releaning every 2000' during the climb.
flyguy
Well-Known Member
Re: High altitude (for a 172 anyway)leaning proced
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During cruise I usually lean the mixture until I get some roughness, then enrichen the mixture a little.
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Dang. I've been using the EGT gauge all this time.....
[/ QUOTE ]
Too bad not all of us have the luxury of an operable EGT all the time.
Most of our instructors teach the "Oh [censored] !" method.
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During cruise I usually lean the mixture until I get some roughness, then enrichen the mixture a little.
[/ QUOTE ]
Dang. I've been using the EGT gauge all this time.....
[/ QUOTE ]
Too bad not all of us have the luxury of an operable EGT all the time.
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I was wondering how you guys lean when climbing to 10,000 or better. I usually only depart from 1000 and cruise and 5000 and lean when I get there. Do you lean on the climb a few times? Also on the descent, what procedure to you use there?
[/ QUOTE ]
Check out this link:
John Deakin's Columns on AvWeb
TONS of well writen piston engine management info along the right hand side as you scroll down.
I was wondering how you guys lean when climbing to 10,000 or better. I usually only depart from 1000 and cruise and 5000 and lean when I get there. Do you lean on the climb a few times? Also on the descent, what procedure to you use there?
[/ QUOTE ]
Check out this link:
John Deakin's Columns on AvWeb
TONS of well writen piston engine management info along the right hand side as you scroll down.
USMCmech
Well-Known Member
Generally enrichening the mixture durring the low power descent is pretty pointless.
At low power durring descent the engine is basicly pumping fuel overboard, not converting it into work.
However when you get to your lower altitude and need power from the engine again you'll need the proper mixture.
I gererally descend at whatever mixture setting was used at cruise, and go to full rich when I level out at a low altitude.
Mixture, prop, throttle should always be on your landing checklist. So if you ever need to do a go around, you'll have full power available.
At low power durring descent the engine is basicly pumping fuel overboard, not converting it into work.
However when you get to your lower altitude and need power from the engine again you'll need the proper mixture.
I gererally descend at whatever mixture setting was used at cruise, and go to full rich when I level out at a low altitude.
Mixture, prop, throttle should always be on your landing checklist. So if you ever need to do a go around, you'll have full power available.
MidlifeFlyer
Well-Known Member
Re: High altitude (for a 172 anyway)leaning proced
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What about descending then?
Do you gradually enrich the mixture on the way down, or go for "Full Rich" from the outset?
[/ QUOTE ] First of all, at high elevation airports, we don't go full rich even for landing in most normally-aspirated aircraft (there are exceptions), so even our final power setting is an approximation.
But, yes, I do tweak the mixture bit by bit during the descent. As USMCmech said, probably doesn't matter much at low power settings, but my enroute descent is usually at cruise or slow cruise power and, even if a bit lower, I'd rather have the approximate setting I need if I need to stop my descent in a hurry..
[ QUOTE ]
What about descending then?
Do you gradually enrich the mixture on the way down, or go for "Full Rich" from the outset?
[/ QUOTE ] First of all, at high elevation airports, we don't go full rich even for landing in most normally-aspirated aircraft (there are exceptions), so even our final power setting is an approximation.
But, yes, I do tweak the mixture bit by bit during the descent. As USMCmech said, probably doesn't matter much at low power settings, but my enroute descent is usually at cruise or slow cruise power and, even if a bit lower, I'd rather have the approximate setting I need if I need to stop my descent in a hurry..