Mixture rich for taxi?
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Mixture rich for taxi?
Just a question on what other people were taught/do. As a pilot who just flies for the fun of it, I enjoy hiring different aircraft and flying in different areas of Australia. Where I was taught to fly, after start-up the mixture is leaned and stays there until your before take-off checks, from the abinitio trainer to twins. In other places I have hired from, the instructors have forbidden me from leaning the mixture at all. One of them said it is better to foul up the plugs and then clear them at the run-up in preference to taking off with the mixture inadvertantly still leaned.
Is leaning the mixture on the ground an acceptable practice?
Is leaning the mixture on the ground an acceptable practice?
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Ever since I learnt about ground leaning I have done it.
Use ground leaning to prevent fouled plugs. If you read anything about engine care you will learn to never burn a plug off if you get a bad mag drop. The reason for this is because engines have nowhere near as much cooling airflow on the ground as in the air and so all you are doing is heating the engine up excessively, and if you arent careful you will heat it to dangerous levels.
A tip to prevent yourself taking off with a leaned mixture is as always use a good and thorough set of checks and also, when ground leaning, lean it so much so the engine starts to die then push the mixture up a bit. You will then find if you try to advance the throttle the engine will just die, reminding you to richen the mixture.
Use ground leaning to prevent fouled plugs. If you read anything about engine care you will learn to never burn a plug off if you get a bad mag drop. The reason for this is because engines have nowhere near as much cooling airflow on the ground as in the air and so all you are doing is heating the engine up excessively, and if you arent careful you will heat it to dangerous levels.
A tip to prevent yourself taking off with a leaned mixture is as always use a good and thorough set of checks and also, when ground leaning, lean it so much so the engine starts to die then push the mixture up a bit. You will then find if you try to advance the throttle the engine will just die, reminding you to richen the mixture.
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During my ab initio training (Up to GFPT) I was taught to leave the mixture full rich for all phases of the flight. This was also policy up to multi engine students because some international students in the past had leaned the mixtures a little too much during flight and ended up costing the flying school a lot more than their savings in "new engines".
During PPL training I was taught to lean the mixture during taxy, then the first thing on the run-up checklist is mixture full rich... Then lean the mixture again just after vacating the runway as part of the after landing checks.
Only during the Commercial and IFR navs are we allowed to lean the mixture during flight.
During PPL training I was taught to lean the mixture during taxy, then the first thing on the run-up checklist is mixture full rich... Then lean the mixture again just after vacating the runway as part of the after landing checks.
Only during the Commercial and IFR navs are we allowed to lean the mixture during flight.
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Only during the Commercial and IFR navs are we allowed to lean the mixture during flight
I think you should be taught to lean in the air and on the ground from day one as this should breed good habits from the begining.
As for the clearing a fouled plug, if you have a CSU try cycling the CSU once or twice as the change in pressure can dislodge the carbon on the plug.
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Hmmm. I wonder who decides?
My first question on an aircraft question is always: "What does the flight manual say?" and if there is no joy there: "What does the engineer say?" and THEN asking a wise instructor.
As to leaning on the ground, two of our C152 trainers are totally different in ground handling. One need full rich to taxi, and the other half mixture. But that has been decided in talks with owner and engineer. Fuel flows at those power settings are very small to be unnoticed in the bottom line.
ECT?
As to leaning on the ground, two of our C152 trainers are totally different in ground handling. One need full rich to taxi, and the other half mixture. But that has been decided in talks with owner and engineer. Fuel flows at those power settings are very small to be unnoticed in the bottom line.
ECT?
Any school that does not give a private pilot ALL the knowledge they need to operate the aircraft correctly is doing them a disservice. Better to teach them how to do it right from the start than to have their private pilots running out of fuel because they were never taught how to lean.
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It does seem to help a little on some types that are a bit prone to plug fouling during extensive taxiing, (E.g. 182RG.) The trick is to remember to put it back to fully rich before take-off. I knew a guy who lined up, opened the throttle fully for take-off and the engine promptly stopped. (Slightly embarassing!)
As for leaning in the air, its often essential if you want to actually get to where you are supposed to be going because the book fuel burn figures are always based on a properly leaned mixture. Also, to get max power available, lean for take-offs from hot and high fields. Personally, I've never come accross any but if some schools are teaching not to use the mixture control, they are a bit remiss. An EGT gauge is a great idea to help get closer to max power, max economy etc. Just shows you how 'old tech' aircraft engines are - a mixture control? in this day and age? The motoring fraternilty worked out how to get rid of those back in about 1920! Role on FADEC.
As for leaning in the air, its often essential if you want to actually get to where you are supposed to be going because the book fuel burn figures are always based on a properly leaned mixture. Also, to get max power available, lean for take-offs from hot and high fields. Personally, I've never come accross any but if some schools are teaching not to use the mixture control, they are a bit remiss. An EGT gauge is a great idea to help get closer to max power, max economy etc. Just shows you how 'old tech' aircraft engines are - a mixture control? in this day and age? The motoring fraternilty worked out how to get rid of those back in about 1920! Role on FADEC.
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jsmitty01..
depends on the type you're flying...aircraft and engine...( an inverted engine again requires different handling )..and even sometimes one engine may be a little more rich than another on aircraft of the same type...
also depends on tha altitude of the airfield...
but remember that fuel is cooling as well ...so the leaner the hotter and for close cowled high performance engines that could be a bad thing...
so by and large i would always use fully rich on the ground ( i am at sea level ) unless there is good reason to do otherwise.
dean
depends on the type you're flying...aircraft and engine...( an inverted engine again requires different handling )..and even sometimes one engine may be a little more rich than another on aircraft of the same type...
also depends on tha altitude of the airfield...
but remember that fuel is cooling as well ...so the leaner the hotter and for close cowled high performance engines that could be a bad thing...
so by and large i would always use fully rich on the ground ( i am at sea level ) unless there is good reason to do otherwise.
dean
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Any school that does not give a private pilot ALL the knowledge they need to operate the aircraft correctly is doing them a disservice. Better to teach them how to do it right from the start than to have their private pilots running out of fuel because they were never taught how to lean.
I do agree that we should be taught to lean earlier but too many idiots messed up engines so I see their point.
multi_engined
Your flight school plans endurance at full rich mixture?
Your flight school plans endurance at full rich mixture?
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Teaching to plan with a rich mixture and not lean. 
Wonder if theses schools are teaching what the foot rests are for yet?
One day they will explain how they control the rudders in the air not just the nose wheel and brakes on the ground.
Multi - I would seriously consider changing schools.
Wonder if theses schools are teaching what the foot rests are for yet?
One day they will explain how they control the rudders in the air not just the nose wheel and brakes on the ground.
Multi - I would seriously consider changing schools.
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Don’t quote me on this, but the above practise of not leaning the mixture in flight, is common training for a lot of "airline cadets" that fly in and out of Parafield.
It wasn’t long ago that I was talking to a friend of mine and he said that his instructor nearly killed him when he started to lean the mixture during this IFR training... words to the effect of, "we never ever touch that lever in flight". Maybe the instructor feels like he/she is flying a turbine/jet aircraft, which we all know don’t have a mixture lever. Not too sure if this is policy at this flying school, but I am under the impression that each aircraft you fly should be flown in accordance to the relevant POH. A good pilot flies a C152 within the parameters set out in the POH, likewise for a PA31 all the way up to a B747....
This practise of not leaning the mixture is nothing new, have heard about it before. Also some flying schools have SOP that all flights must have full tanks before any departure (regardless of flight time duration)...again a bad habit to get into as in the "real world" it isn’t just you and the instructor, there are PAX or cargo that also needs to be transported...most aircraft cant have full tanks and max payload, without being over MTOW. Lets see these flying schools get away with doing a few flights on MINIMUM fuel, have to divert and land at an alternate airport, without cutting into their reserves! I personally can’t recall any POH that states a fuel flow for full rich operations....
From past experiences and memory a P28A if leaned should burn around 31-32l/hr, a C182 around 42-47l/hr, C206/C210 around 55-60l/hr...Now if you were not to lean a C182, 206,210 fuel flow would be up around say 80l/hr? (Or there abouts). Now when flying fuel critical, its only a matter of time until you would run out of juice!
The mixture lever is there for a reason, USE IT!
As for leaning on the taxi, as stated before it depends on the individual aircraft some foul-up if not leaned, others will purr like a kitten.
Again I must stress don’t quote me on the above, with regards to a certain flying school telling their students not to use the mixture, "as you wont be flying pistons for too much longer". It just came up in conversation a few days ago...
Blue skies and happy landings!
CMN
It wasn’t long ago that I was talking to a friend of mine and he said that his instructor nearly killed him when he started to lean the mixture during this IFR training... words to the effect of, "we never ever touch that lever in flight". Maybe the instructor feels like he/she is flying a turbine/jet aircraft, which we all know don’t have a mixture lever. Not too sure if this is policy at this flying school, but I am under the impression that each aircraft you fly should be flown in accordance to the relevant POH. A good pilot flies a C152 within the parameters set out in the POH, likewise for a PA31 all the way up to a B747....
This practise of not leaning the mixture is nothing new, have heard about it before. Also some flying schools have SOP that all flights must have full tanks before any departure (regardless of flight time duration)...again a bad habit to get into as in the "real world" it isn’t just you and the instructor, there are PAX or cargo that also needs to be transported...most aircraft cant have full tanks and max payload, without being over MTOW. Lets see these flying schools get away with doing a few flights on MINIMUM fuel, have to divert and land at an alternate airport, without cutting into their reserves! I personally can’t recall any POH that states a fuel flow for full rich operations....
From past experiences and memory a P28A if leaned should burn around 31-32l/hr, a C182 around 42-47l/hr, C206/C210 around 55-60l/hr...Now if you were not to lean a C182, 206,210 fuel flow would be up around say 80l/hr? (Or there abouts). Now when flying fuel critical, its only a matter of time until you would run out of juice!
The mixture lever is there for a reason, USE IT!
As for leaning on the taxi, as stated before it depends on the individual aircraft some foul-up if not leaned, others will purr like a kitten.
Again I must stress don’t quote me on the above, with regards to a certain flying school telling their students not to use the mixture, "as you wont be flying pistons for too much longer". It just came up in conversation a few days ago...
Blue skies and happy landings!
CMN
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Ever since I learnt about ground leaning I have done it.
Use ground leaning to prevent fouled plugs. If you read anything about engine care you will learn to never burn a plug off if you get a bad mag drop. The reason for this is because engines have nowhere near as much cooling airflow on the ground as in the air and so all you are doing is heating the engine up excessively, and if you arent careful you will heat it to dangerous levels.
.
Use ground leaning to prevent fouled plugs. If you read anything about engine care you will learn to never burn a plug off if you get a bad mag drop. The reason for this is because engines have nowhere near as much cooling airflow on the ground as in the air and so all you are doing is heating the engine up excessively, and if you arent careful you will heat it to dangerous levels.
.
I would suggest a reference to your partular aircraft's flight manual would be prudent. I can not believe that schools are teaching to run their aircraft at full rich in flight - it not only is bad for the engine but degrades the aircraft's performance as well.
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Two of our aircraft will foul on the ground if not leaned out. I only run full rich for run ups and as i'm lining up. I was always taught to guard the throttle quadrant with my hand across all 3 (2?) in the take off roll, an out of place mixture would soon be found. At worst a little bump up to full rich as the throttle goes up and a little mental kick in the ar$e.
It's not a good look for your pax if you haven't leaned it out on the ground and during the mag check she starts coughing and shaking.
Also with our Turbo Lance (with a wonderful little digital fuel flow meter) the full rich fuel flow in cruise is around 90-95l/hr!!! Leaned to max power you're down to 60l/hr. Off the top of my head (with a smidge of help from the calculator) that's a range (with reserves) of about 780nm as opposed to 525nm. That could give you a nasty little fright 250nm from home!!!
It's not a hard thing to learn to do properly, there's alot more complicated stuff in that cockpit that's for sure! If they're not teaching you how to use that little red lever properly, what else aren't they teaching you?
A bit off topic, but ContactMeNow's post reminded me. Years ago i was shown an easy way to get a rough fuel flow for a properly leaned engine running at about 65% power:
Double the horsepower and take off a '0'. Simple
I'm only talking Conti's and Lyc's and none too complicated, but has proved to be a useful little formula over the years.
182 (230hp) eg. 2 X 230 = 460 = 46l/hr
PA-32 (300hp) = 60l/hr
172 (160hp) = 32l/hr
PA-44 (360hp total) =72l/hr
Again, only as a rough guide, but it's been proven remarkably accurate time and time again.
It's not a good look for your pax if you haven't leaned it out on the ground and during the mag check she starts coughing and shaking.
Also with our Turbo Lance (with a wonderful little digital fuel flow meter) the full rich fuel flow in cruise is around 90-95l/hr!!! Leaned to max power you're down to 60l/hr. Off the top of my head (with a smidge of help from the calculator) that's a range (with reserves) of about 780nm as opposed to 525nm. That could give you a nasty little fright 250nm from home!!!
It's not a hard thing to learn to do properly, there's alot more complicated stuff in that cockpit that's for sure! If they're not teaching you how to use that little red lever properly, what else aren't they teaching you?
A bit off topic, but ContactMeNow's post reminded me. Years ago i was shown an easy way to get a rough fuel flow for a properly leaned engine running at about 65% power:
Double the horsepower and take off a '0'. Simple
I'm only talking Conti's and Lyc's and none too complicated, but has proved to be a useful little formula over the years.
182 (230hp) eg. 2 X 230 = 460 = 46l/hr
PA-32 (300hp) = 60l/hr
172 (160hp) = 32l/hr
PA-44 (360hp total) =72l/hr
Again, only as a rough guide, but it's been proven remarkably accurate time and time again.
One place I worked employed a "senior" pilot. He came back from a flight to go out again on full tanks and a quick glance at the truck meter showed that he had 10 litres left in the tanks.... 
I ran a few numbers and realised that was what you'd expect over that route at full rich.
He moved on elsewhere.
I ran a few numbers and realised that was what you'd expect over that route at full rich.
He moved on elsewhere.
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I have hired from three seperate flying schools at Parafield and I have never once been told to lean the mixture on the ground! They all used the 'only above 5000 ft rule' which I have stuck with to this day.
Cheers. PA
Cheers. PA
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Yes it will make it hotter but running around at 1000rpm you won't be making anywhere as much heat as you would do running it up to say 2000rpm or higher to burn off a mag. The purpose of ground leaning is to stop fouled plugs.