Mixture rich for taxi?
Fuel is included in the hourly rate. There is no direct financial incentive for me to lean.
As a lowly PPL, SOP's taught to me were:
1. Rich most of the time, certainly in the circuit and on the ground, lean it on the ground to clear the plugs on the Arrow and suchlike if excessive mag drop. C172's and Arrows don't seem to foul the plugs much.
2. Leaning below 5000 feet is optional.
I make leaning a cruise activity once everything is nicely trimmed, plan and logs updated, and all else sorted.
Planning figures for flights are at Ops manual numbers which are full rich. Eg. 36L/H for C172/Warrior and at a nominated cruise eg. 110 kts.
Call me stupid and lazy, but I prefer to plan/fly on the five hour fuel and three hour bladder principle. Full tanks, three hours max between refueling/Loo stops leaves two hours reserves at full rich. If I've leaned in cruise even more reserves.
I will do the ground fuel/climb fuel/cruise fuel/ etc. if provoked, but if it becomes essential, then that usually means I'm pushing a weight or runway length limit somewhere, so I'll replan or find another aircraft.
I know its not professional.....but I'm not a professional.
As a lowly PPL, SOP's taught to me were:
1. Rich most of the time, certainly in the circuit and on the ground, lean it on the ground to clear the plugs on the Arrow and suchlike if excessive mag drop. C172's and Arrows don't seem to foul the plugs much.
2. Leaning below 5000 feet is optional.
I make leaning a cruise activity once everything is nicely trimmed, plan and logs updated, and all else sorted.
Planning figures for flights are at Ops manual numbers which are full rich. Eg. 36L/H for C172/Warrior and at a nominated cruise eg. 110 kts.
Call me stupid and lazy, but I prefer to plan/fly on the five hour fuel and three hour bladder principle. Full tanks, three hours max between refueling/Loo stops leaves two hours reserves at full rich. If I've leaned in cruise even more reserves.
I will do the ground fuel/climb fuel/cruise fuel/ etc. if provoked, but if it becomes essential, then that usually means I'm pushing a weight or runway length limit somewhere, so I'll replan or find another aircraft.
I know its not professional.....but I'm not a professional.
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I get annoyed when I get invoices from my LAME for 'cleaning fouled plugs' caused by twits who don't ground-lean. (If the twits are very lucky, plug-cleaning might only delay their flight by a couple of hours.)
Ground-leaning also gets the oil temperature up to a reasonable value, especially on winter-mornings.
As for operating rich-in-cruise, if you look at the mixture/temperature/power charts then you'll see that a full-rich setting will reduce the produced power (as compared to the 'best power' mixture value).
sunfish
That is only the case if you fuel-up at your home base.
Do a 20+ hour flyaway where fuel can be $2.30+ per litre, or where you have to zigzag your planned track so that the next fuel point is within your 'full-rich' endurance and you'll soon become a convert to always leaning.
Now as to leaning in climb..., let the battle begin !
Ground-leaning also gets the oil temperature up to a reasonable value, especially on winter-mornings.
As for operating rich-in-cruise, if you look at the mixture/temperature/power charts then you'll see that a full-rich setting will reduce the produced power (as compared to the 'best power' mixture value).
sunfish
Fuel is included in the hourly rate. There is no direct financial incentive for me to lean.
Do a 20+ hour flyaway where fuel can be $2.30+ per litre, or where you have to zigzag your planned track so that the next fuel point is within your 'full-rich' endurance and you'll soon become a convert to always leaning.
Now as to leaning in climb..., let the battle begin !
Last edited by Biggles_in_Oz; 28th Oct 2006 at 23:54.
With appologies to Mr Deakin, the most authoritive articles EVER written about engine management for aircraft. These should be mandatory reading!
Pelican's Perch
Leaning on the Ground
I believe this is a "a very good thing" to do. Most of these engines are set up with a very rich idle mixture, to facilitate starting when cold. This mixture adjustment applies only to the very low power settings used for taxi. In most engines, somewhere at and above about 1200 RPM, the idle mixture setting is overridden by the normal functioning of the carburetor or fuel injection control, and other factors come into play.
How rich is your idle mixture? There's a very easy way to check. You want a nice warm engine for this check, so doing it at shutdown after landing is one good time to do it. Just set an RPM around the usual RPM you use for normal taxiing (I use 900 to 1,000) and start leaning, while watching the RPM very closely. Just before the engine quits, you should see a slight rise in RPM, then a quick fall. (This is very easy with the vernier type mixture controls, a bit more difficult with the push-pull knobs.)
(Note: This is not the way mechanics set the idle mixture! They use minimum idle RPM, or as called for by the book. I'm more interested in the mixture at the engine speed I use most of the time, on the ground.)
Note the amount of rise. You may see "almost nothing" on the big radials, to 50 RPM, or a bit more on some of the flat engines. If the engine was adjusted for sea level, and you do the test at Creede, Colorado (elevation 9,000 ft.), you'll see a very large increase, indeed! The mixture jet is a fixed size, so about the same volume of fuel will pass at all altitudes, but at altitude there is much less air, so the proportion changes to the rich side, and you really need to lean for all ground operations!
OK, why bother leaning on the ground? Most of these engines run ok on the ground at full rich, right? Well, not really. The unburned fuel is very dirty, and tends to foul spark plugs.
Also, over time, these unburned products work their way into the valve guides, causing them to stick, especially when cold (aka "Morning Sickness," from the first start of the day). Eventually this may lead to a valve sticking open enough that the piston will start beating on it, and that's not a good thing!
I've faithfully leaned on the ground for the past 800 hours or so, and have never once had a fouled plug, or a problem with an exhaust guide.
Be Brutal
The only downside I know of to leaning on the ground is that it creates the possibility of forgetting to go full rich, and taking off that way. But there is an excellent method for preventing this—simply lean so brutally that taking off is impossible. As soon as the engine has stabilized after starting, lean it out until you get that RPM rise, then an RPM fall, or until the engine begins to run rough, then enrich it just slightly, just barely enough to make it run smooth. No, you cannot hurt the engine by doing this since you're pulling virtually no power.
Look at this simple chart, which is actual data from my IO-550 for an engine start, runup, and beginning of the takeoff roll. There are several interesting things here. There will be additional charts, all in this same format, and all recorded from a JPI EDM-700 Engine Monitor, connected to a personal computer, and later graphed in Excel 97 (one of Microsoft's finest efforts). To reduce clutter, I have graphed only the hottest EGT and CHT (#2 on my engine, by a very small margin) and fuel flow. In order to get everything nicely placed on the graph for clarity, I have simply multiplied the very low fuel flow by 100, so both fuel flow (times 100) and CHT can be read on the right scale, with EGT on the left scale. All data points are captured at six-second intervals, which doesn't miss much.
Note the long, slow, even rise of CHT. This is very typical of all changes in CHT, for the engine is a massive heat sink, and it takes a long time to change its temperature in either direction. This CHT probe is buried deep in the cylinder casting, and is an excellent measure of internal engine temperature. Watching these CHT traces also gives the lie to some of the "shock cooling" theories, but that's for another time.
By contrast, note how quickly the EGT changes. It's instantaneous, and this is very useful in flight. It is possible see a CHT that is too hot, or increasing, and just tweak the mixture enough to get a 20F or 50F change in EGT, then wait for a minute or three, and the CHT will gradually follow.
Finally, look at the fuel flow trace. Before turning the engine, I prime it with the boost pump for a few seconds, throttle cracked, mixture full rich, and that runs about 8 gph into the engine. Boost off, and immediately hit the starter.
You see the EGT rise rapidly as the engine starts, and the fuel flow stabilizes at about 4 gph, in full rich. As soon as the engine is running smoothly I lean it right out until the engine falters, then enrich just barely enough to get it to smooth out. This is so very lean, I cannot get much more than about 1200 RPM, and it's about 2.7 GPH.
I’m Not Being Cheap
Now, airline captains are cheap, but even I am not cheap enough to worry about wasting that 1.3 GPH for a few minutes on the ground. But if you've ever wondered why spark plugs foul during ground operations, I think you're looking at the reason.
For runup, just a touch of extra mixture will allow 1500 to 1700 RPM for the prop check, and a quick mag check, then back to about 1,000 RPM, and a quick twist back on the mixture again. This is important, remember, to prevent taking off with that mixture not in full rich. In my opinion, if you will not lean it right out, almost to the point of roughness, then never mind leaning at all on the ground, just leave it in full rich at all times on the ground. I'd rather see you with fouled plugs, than a ruined engine, or worse!
You will note that EGT always rises during the time you operate on one mag, during the mag check. This is because with only one plug firing, more of the mixture is still burning as it exits through the opening exhaust valve, and since the EGT probe is just outside that valve, it "sees" the still-burning mixture, and shows a higher value. This is just one of many things that will cause a misleading EGT indication. Additionally, if you check the mags while leaned out, the mixture is burning much more slowly, so even more burning mixture escapes. Since this burning is not taking place within the combustion chamber, even more power is lost, so you'll see a greater mag drop during a check. If this makes you uncomfortable, go full rich for the check, and then just leave it there for the takeoff.
A side note on the big radials, which have "Auto Rich," "Auto Lean" and "Idle Cutoff" positions. There is a small, but noisy group of people who insist on operating them on the ground in Auto Lean, thinking they are accomplishing some of the above "good things." Not true, on those engines, at and below about 1200 or 1400 RPM, on the ground, there is no difference at all between Auto Rich and Auto Lean. If there was a difference, you'd see a slight RPM change. In order to enjoy the above benefits, those engines must be manually leaned, almost back to the Idle Cutoff position, to do any good. They are also generally set up to idle much leaner than flat engines, so unless they are maladjusted, it's better to just operate in Auto Rich on the ground. The danger with the Auto Lean position on a big radial is that it will allow takeoff power to be set, with potentially catastrophic results from detonation.
Pelican's Perch
Leaning on the Ground
I believe this is a "a very good thing" to do. Most of these engines are set up with a very rich idle mixture, to facilitate starting when cold. This mixture adjustment applies only to the very low power settings used for taxi. In most engines, somewhere at and above about 1200 RPM, the idle mixture setting is overridden by the normal functioning of the carburetor or fuel injection control, and other factors come into play.
How rich is your idle mixture? There's a very easy way to check. You want a nice warm engine for this check, so doing it at shutdown after landing is one good time to do it. Just set an RPM around the usual RPM you use for normal taxiing (I use 900 to 1,000) and start leaning, while watching the RPM very closely. Just before the engine quits, you should see a slight rise in RPM, then a quick fall. (This is very easy with the vernier type mixture controls, a bit more difficult with the push-pull knobs.)
(Note: This is not the way mechanics set the idle mixture! They use minimum idle RPM, or as called for by the book. I'm more interested in the mixture at the engine speed I use most of the time, on the ground.)
Note the amount of rise. You may see "almost nothing" on the big radials, to 50 RPM, or a bit more on some of the flat engines. If the engine was adjusted for sea level, and you do the test at Creede, Colorado (elevation 9,000 ft.), you'll see a very large increase, indeed! The mixture jet is a fixed size, so about the same volume of fuel will pass at all altitudes, but at altitude there is much less air, so the proportion changes to the rich side, and you really need to lean for all ground operations!
OK, why bother leaning on the ground? Most of these engines run ok on the ground at full rich, right? Well, not really. The unburned fuel is very dirty, and tends to foul spark plugs.
Also, over time, these unburned products work their way into the valve guides, causing them to stick, especially when cold (aka "Morning Sickness," from the first start of the day). Eventually this may lead to a valve sticking open enough that the piston will start beating on it, and that's not a good thing!
I've faithfully leaned on the ground for the past 800 hours or so, and have never once had a fouled plug, or a problem with an exhaust guide.
Be Brutal
The only downside I know of to leaning on the ground is that it creates the possibility of forgetting to go full rich, and taking off that way. But there is an excellent method for preventing this—simply lean so brutally that taking off is impossible. As soon as the engine has stabilized after starting, lean it out until you get that RPM rise, then an RPM fall, or until the engine begins to run rough, then enrich it just slightly, just barely enough to make it run smooth. No, you cannot hurt the engine by doing this since you're pulling virtually no power.
Look at this simple chart, which is actual data from my IO-550 for an engine start, runup, and beginning of the takeoff roll. There are several interesting things here. There will be additional charts, all in this same format, and all recorded from a JPI EDM-700 Engine Monitor, connected to a personal computer, and later graphed in Excel 97 (one of Microsoft's finest efforts). To reduce clutter, I have graphed only the hottest EGT and CHT (#2 on my engine, by a very small margin) and fuel flow. In order to get everything nicely placed on the graph for clarity, I have simply multiplied the very low fuel flow by 100, so both fuel flow (times 100) and CHT can be read on the right scale, with EGT on the left scale. All data points are captured at six-second intervals, which doesn't miss much.
Note the long, slow, even rise of CHT. This is very typical of all changes in CHT, for the engine is a massive heat sink, and it takes a long time to change its temperature in either direction. This CHT probe is buried deep in the cylinder casting, and is an excellent measure of internal engine temperature. Watching these CHT traces also gives the lie to some of the "shock cooling" theories, but that's for another time.
By contrast, note how quickly the EGT changes. It's instantaneous, and this is very useful in flight. It is possible see a CHT that is too hot, or increasing, and just tweak the mixture enough to get a 20F or 50F change in EGT, then wait for a minute or three, and the CHT will gradually follow.
Finally, look at the fuel flow trace. Before turning the engine, I prime it with the boost pump for a few seconds, throttle cracked, mixture full rich, and that runs about 8 gph into the engine. Boost off, and immediately hit the starter.
You see the EGT rise rapidly as the engine starts, and the fuel flow stabilizes at about 4 gph, in full rich. As soon as the engine is running smoothly I lean it right out until the engine falters, then enrich just barely enough to get it to smooth out. This is so very lean, I cannot get much more than about 1200 RPM, and it's about 2.7 GPH.
I’m Not Being Cheap
Now, airline captains are cheap, but even I am not cheap enough to worry about wasting that 1.3 GPH for a few minutes on the ground. But if you've ever wondered why spark plugs foul during ground operations, I think you're looking at the reason.
For runup, just a touch of extra mixture will allow 1500 to 1700 RPM for the prop check, and a quick mag check, then back to about 1,000 RPM, and a quick twist back on the mixture again. This is important, remember, to prevent taking off with that mixture not in full rich. In my opinion, if you will not lean it right out, almost to the point of roughness, then never mind leaning at all on the ground, just leave it in full rich at all times on the ground. I'd rather see you with fouled plugs, than a ruined engine, or worse!
You will note that EGT always rises during the time you operate on one mag, during the mag check. This is because with only one plug firing, more of the mixture is still burning as it exits through the opening exhaust valve, and since the EGT probe is just outside that valve, it "sees" the still-burning mixture, and shows a higher value. This is just one of many things that will cause a misleading EGT indication. Additionally, if you check the mags while leaned out, the mixture is burning much more slowly, so even more burning mixture escapes. Since this burning is not taking place within the combustion chamber, even more power is lost, so you'll see a greater mag drop during a check. If this makes you uncomfortable, go full rich for the check, and then just leave it there for the takeoff.
A side note on the big radials, which have "Auto Rich," "Auto Lean" and "Idle Cutoff" positions. There is a small, but noisy group of people who insist on operating them on the ground in Auto Lean, thinking they are accomplishing some of the above "good things." Not true, on those engines, at and below about 1200 or 1400 RPM, on the ground, there is no difference at all between Auto Rich and Auto Lean. If there was a difference, you'd see a slight RPM change. In order to enjoy the above benefits, those engines must be manually leaned, almost back to the Idle Cutoff position, to do any good. They are also generally set up to idle much leaner than flat engines, so unless they are maladjusted, it's better to just operate in Auto Rich on the ground. The danger with the Auto Lean position on a big radial is that it will allow takeoff power to be set, with potentially catastrophic results from detonation.
Last edited by OZBUSDRIVER; 29th Oct 2006 at 00:13. Reason: spacing for paragraphs
What are flying schools teaching people these days?????? It probably comes down to the fact that the majority of instructors these days are fresh CPL's who are too scared to lean the thing themselves, so they don't teach others properly!!
If I were to keep a Baron at full rich at our cruise power setting we use, at say 8,000ft, it'd be up around the 135L/hr mark, just in the cruise!! Compare that to a properly leaned setting of around 110L/hr. That's a big difference, and a lot of money!
Worse still, try doing that in a Chieftain! A typical cruise fuel flow (31" MAP and 2,200Rpm) is around the 137L/hr mark. Keep it full rich and you'll burn around the 180-190L/hr mark,
.
Get some of these suckers into things like charter etc., where you run around near on fuel critical all the time, and they'd be running out of fuel,
.
For your own sake, change flying schools mate, and learn how to lean it properly.
morno
If I were to keep a Baron at full rich at our cruise power setting we use, at say 8,000ft, it'd be up around the 135L/hr mark, just in the cruise!! Compare that to a properly leaned setting of around 110L/hr. That's a big difference, and a lot of money!
Worse still, try doing that in a Chieftain! A typical cruise fuel flow (31" MAP and 2,200Rpm) is around the 137L/hr mark. Keep it full rich and you'll burn around the 180-190L/hr mark,
.Get some of these suckers into things like charter etc., where you run around near on fuel critical all the time, and they'd be running out of fuel,
.For your own sake, change flying schools mate, and learn how to lean it properly.
morno
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Off topic (again), but wouldn't that 500TT/9 mths commercial experience rule for Cheif Pilots be a great one for instructors!!! 200hrs teaching others to fly is just crazy!!!!
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I have an HIO-360 in my 1946 Swift and IF I don't lean it for taxi, by the time I am at the runway, the plugs are usually fouled and the mag drop is considerable.
On takeoff, I push the throttle up and never move it until I pull it back in the pattern for landing. At cruise altitude, I lean the engine to the lean side of peak.
It seems most are now taught to be very careful with leaning to the point that few lean the engines out. Deakin and others have researched how the old big recips increased their life cycles and it was NOT by running rich of peak.
On takeoff, I push the throttle up and never move it until I pull it back in the pattern for landing. At cruise altitude, I lean the engine to the lean side of peak.
It seems most are now taught to be very careful with leaning to the point that few lean the engines out. Deakin and others have researched how the old big recips increased their life cycles and it was NOT by running rich of peak.
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This in turn will give an over, over supply of pilots "up north", thus making it even harder for Joe Bloggs to get his first gig....
I think its up to the students to educate themselves and say that they only want to be taught, by a grade 1, or a lessor grade, but with charter expereince....
Thats my point of view on the matter anyway
CMN
There's a regulation somewhere which says that even PPL's must follow the Flight Manual. I'm sure that JF would tell you to fly it per the book.
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I am simply stunned by this thread
OZBUSDRIVER - you beat me to it. Johns articles should be required reading in their entirety as you say.
As an aside, the GA training in my day (late 50's, early 60's) taught no leaning below 5,000 and to make sure on the Gypsy engines even removed the mixture control.
At no time was any instruction given on leaning, either theory or practical. Come to think of it my instructors were greenhorns in aviation as well but went on to better things - one chief pilot MD-11 ops, other left seat 747 - retired now tho.
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Well for starters the instructor wage will need to go up, to encourage charter guys/gals to have a go at instructing.
This in turn will give an over, over supply of pilots "up north", thus making it even harder for Joe Bloggs to get his first gig....
I think its up to the students to educate themselves and say that they only want to be taught, by a grade 1, or a lessor grade, but with charter expereince....
Thats my point of view on the matter anyway
CMN
This in turn will give an over, over supply of pilots "up north", thus making it even harder for Joe Bloggs to get his first gig....
I think its up to the students to educate themselves and say that they only want to be taught, by a grade 1, or a lessor grade, but with charter expereince....
Thats my point of view on the matter anyway
CMN
Guess i'm just dreamin'. I still think it's a bad idea letting 200TTers teach others how to fly. Now to do something creative and try to come up with a workable solution.
Don't hold your breath!
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G'day guys,
Generally in the aircraft i fly i will use the following procedures:
- Taxi at 1000rpm so not to foul plugs - without riding the brakes.. so if i speed up too much, then i'll reduce pwr and lean slightly
- Always lean in cruise
- Lean for climbs above 5000'
Carro
Generally in the aircraft i fly i will use the following procedures:
- Taxi at 1000rpm so not to foul plugs - without riding the brakes.. so if i speed up too much, then i'll reduce pwr and lean slightly
- Always lean in cruise
- Lean for climbs above 5000'
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and if there is no joy there: "What does the engineer say?" and THEN asking a wise instructor.
So, what is the thought on leaning in the climb without a fuel flow guage in a normally aspirated fuel injected pistom engine?
Last edited by Atlas Shrugged; 29th Oct 2006 at 23:31.
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Like Chimbu, this thread leaves me gob-smacked.
Why would you Not lean your engine(s)??? Any 260hp Islander will foul if left full-rich -those Lycomings run excessively rich (on the ground especially) in all flight conditions. My habit is always lean aggressively. On the ground and in-flight. Usual departure is from an airfield at an elevation of 1200', operating to a sea-level airfield, with operation up to FL120. After take-off, when the airframe is cleaned-up with a positive and sustainable rate-of-climb established (usually around 50' - 100'), the engines are leaned to the 'top of the R' on the mixtuRe quadrant -and there its stays throughout the flight. On approach the mixture is enriched to about 1/2-quadrant. I don't want it full-rich: in case of a go-around I need my engines to respond immediately, not after they have chewed on and cleared the massive over-rich condition of a full-rich mixture.
My engines are in the habit of going TBO (2000 hrs + 200 on-condition) without issue. No fouled plugs, no blown cylinder heads, no detonation. They run sweet and willingly, give me great block-times and low fuel consumption (usually around 52 - 55 lph).
Flame on...
Can anyone explain to me (with appropriate supporting evidence) why you would not lean an engine below 5000'?
Why would you Not lean your engine(s)??? Any 260hp Islander will foul if left full-rich -those Lycomings run excessively rich (on the ground especially) in all flight conditions. My habit is always lean aggressively. On the ground and in-flight. Usual departure is from an airfield at an elevation of 1200', operating to a sea-level airfield, with operation up to FL120. After take-off, when the airframe is cleaned-up with a positive and sustainable rate-of-climb established (usually around 50' - 100'), the engines are leaned to the 'top of the R' on the mixtuRe quadrant -and there its stays throughout the flight. On approach the mixture is enriched to about 1/2-quadrant. I don't want it full-rich: in case of a go-around I need my engines to respond immediately, not after they have chewed on and cleared the massive over-rich condition of a full-rich mixture.
My engines are in the habit of going TBO (2000 hrs + 200 on-condition) without issue. No fouled plugs, no blown cylinder heads, no detonation. They run sweet and willingly, give me great block-times and low fuel consumption (usually around 52 - 55 lph).
Flame on...
Can anyone explain to me (with appropriate supporting evidence) why you would not lean an engine below 5000'?
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Sadly, it isn't.
Golden rule with all internal combustion engines: give them what they want. That would be a correct fuel/air ratio, and the only way to get that is by moving the lever with the big red knob. There is a reason why they give you that knob to play with!
The clever bit is in understanding what that knob does, and what the carb/throttle body does.
Bear in mind that cars that use modern EFI systems (maybe light aircraft will have those in 100 years or so), are constantly adjusting the fuel/air ratio at ALL engine operating phases (idle, under load, over-run, hot, cold, etc). In your light aircraft with it's ancient systems, YOU are the EFI computer! So learn how to use the red knob, and once you know how to use it, use it all the time. Your engine will love you for it.
I'm not so concerned about the cost of fuel, but knowing that the (single) engine in front of me is having to put up with an incorrect fuel/air ratio just bugs the heck out of me! 'Cos I need it to keep running...
Life is so much simpler in the jet I normally fly, but when I get back in a piston aircraft, you can bet that I want to operate it correctly, and there is a TON of info out there on how to do so.
The trick is in sorting the urban myths from the good info.
Golden rule with all internal combustion engines: give them what they want. That would be a correct fuel/air ratio, and the only way to get that is by moving the lever with the big red knob. There is a reason why they give you that knob to play with!
The clever bit is in understanding what that knob does, and what the carb/throttle body does.
Bear in mind that cars that use modern EFI systems (maybe light aircraft will have those in 100 years or so), are constantly adjusting the fuel/air ratio at ALL engine operating phases (idle, under load, over-run, hot, cold, etc). In your light aircraft with it's ancient systems, YOU are the EFI computer! So learn how to use the red knob, and once you know how to use it, use it all the time. Your engine will love you for it.
I'm not so concerned about the cost of fuel, but knowing that the (single) engine in front of me is having to put up with an incorrect fuel/air ratio just bugs the heck out of me! 'Cos I need it to keep running...
Life is so much simpler in the jet I normally fly, but when I get back in a piston aircraft, you can bet that I want to operate it correctly, and there is a TON of info out there on how to do so.
The trick is in sorting the urban myths from the good info.
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At my club(I am CFI) we teach ALL students, ppl and cpl all about fuel systems and leaning. Modern lycoming engines should operate at a chemically correct mixture, bearing in mind that fuel is also used as a cooling device in certain conditions(eg, glider towing , paradropping etc, using full power with larger aircraft-and they still need leaning as they climb higher)
Experience with particular aircraft will show that some liked being leaned for taxiing, to aviod plug fouling, others, never seem to foul plugs!
As has been mentioned earlier, consult the aircraft flight manual and a good engineer first!
I place importance on fuel systems and management, some organisations seem scared to lean below 3000 or 5000 ft, even in hot summer conditions.
That is asking for fuel starvation problems(ie: running out of fuel!) and excessive fuel in the cyinders, playing havock with lubrication within, etc etc., not to mention severe plug fouling, which has caused emergency landings in the past- I know of two in the last ten years!
I teach fuel/mixture use from an early stage in training, ppls become confident for cross country's, and any who continue to bigger aircraft as cpls have had a good grounding in fuel/mixture management.
Plug fouling is minimized, fuel use is maximized, engines are looked after(engineers comment). Even a 152 on a cross country at 3,000 ft will use 3 litres per hr less when correctly leaned,achieving cost savings as well.
Thats my thoughts anyway..........I was taught by a WW2 Corsair pilot.
cheers!
Experience with particular aircraft will show that some liked being leaned for taxiing, to aviod plug fouling, others, never seem to foul plugs!
As has been mentioned earlier, consult the aircraft flight manual and a good engineer first!
I place importance on fuel systems and management, some organisations seem scared to lean below 3000 or 5000 ft, even in hot summer conditions.
That is asking for fuel starvation problems(ie: running out of fuel!) and excessive fuel in the cyinders, playing havock with lubrication within, etc etc., not to mention severe plug fouling, which has caused emergency landings in the past- I know of two in the last ten years!
I teach fuel/mixture use from an early stage in training, ppls become confident for cross country's, and any who continue to bigger aircraft as cpls have had a good grounding in fuel/mixture management.
Plug fouling is minimized, fuel use is maximized, engines are looked after(engineers comment). Even a 152 on a cross country at 3,000 ft will use 3 litres per hr less when correctly leaned,achieving cost savings as well.
Thats my thoughts anyway..........I was taught by a WW2 Corsair pilot.
cheers!