Should you lean slightly when taxiing?

Why yes, you should lean forward if you want to go slower and lean back if you want to relax... Leaning right or left is not going to help you, but a lot of students do anyway.

Oh, nevermind.

Yeah, you should always lean when taxiing unless you have a hot running engine that needs the extra fuel to stay cool.
 
RyanShort1 said:
Yeah, you should always lean when taxiing unless you have a hot running engine that needs the extra fuel to stay cool.
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If it ever runs hot enough that it needs extra fuel at idle/taxi power, the baffles and everything else under the cowl made of anything but metal, are probably on fire or about to be.
 
Lean into a headwind and away from a tailwind. Oh, wait. You would always be leaning forward then. I might want to re-read my books. :)
 
From "Aircraft Powerplants, Fourth Edition by Bent Mckinley, page 80: "An increased amount of fuel (richer mixture) is used in the idle range because at idling speeds, the engine may not have enough airflow around it's cylinders to provide proper cooling." Take it for what it's worth.
 
I teach our students and rental pilots to lean our 172s as much as possible. Lean until it starts to quit, then just slightly enrichen so it doesn't quit. I'm a pretty big stickler about this.

We *do not* have problems with spark plugs being fouled ever. Our A&P comments how much better our spark plugs are than all the other airplanes he works on.

If people don't do this, the plugs will indeed foul, and someone will nix a flight because of a poor mag check which will cost us revenue and make them think our airplanes aren't being maintained.

Also we do not have problems with our engines period. We do not have cylinders that are cracking. I have more problems with Cessna flap systems then I do with engines.
 
GlennAB1 said:
In many carbretors, idle enrichment is automatic, there is no controlling it.
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If you teach your customers to run full rich on the ground in most any piston airplane you'll have a ton of very disappointed airplane owners fighting spark plug fouling issues. Please research and educate yourself because it sounds like an instructor at A&P school has something backwards or there was a misunderstanding on the principals they were teaching.


Engines couldn't care less about running lean at ridiculously low power settings (idle/taxi). Correct fuel flows at high power settings (takeoff) are very important.
 
GlennAB1 said:
From "Aircraft Powerplants, Fourth Edition by Bent Mckinley, page 80: "An increased amount of fuel (richer mixture) is used in the idle range because at idling speeds, the engine may not have enough airflow around it's cylinders to provide proper cooling." Take it for what it's worth.
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Generalities which are very unspecific. That may have come from round multi row WWII piston engines installed in bombers and has very little to do with small GA piston airplanes.
 
I have a Rotax 912. No mixture control, it has altitude compensating carbs.

Makes things very simple, but I wish I had at least some mixture control. It can be added with a HACman kit, but IMO it's kind of a kludge, and the engine seems to work great as-is.
 
GlennAB1 said:
From "Aircraft Powerplants, Fourth Edition by Bent Mckinley, page 80: "An increased amount of fuel (richer mixture) is used in the idle range because at idling speeds, the engine may not have enough airflow around it's cylinders to provide proper cooling." Take it for what it's worth.
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book learning is great, learning how to apply the book to the real world is priceless

Who controls the information in a book? What makes that information correct? What is the context of the information?
 
GlennAB1 said:
From "Aircraft Powerplants, Fourth Edition by Bent Mckinley, page 80: "An increased amount of fuel (richer mixture) is used in the idle range because at idling speeds, the engine may not have enough airflow around it's cylinders to provide proper cooling." Take it for what it's worth.
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Citing authorities would settle the argument if the authorities agreed with each other.
 
GlennAB1 said:
From "Aircraft Powerplants, Fourth Edition by Bent Mckinley, page 80: "An increased amount of fuel (richer mixture) is used in the idle range because at idling speeds, the engine may not have enough airflow around it's cylinders to provide proper cooling." Take it for what it's worth.
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Keep an eye on the CHT, over cooling is just as bad as getting too hot as it washes out the rings and promotes cylinder glazing.
 
I attended one of those WINGS seminars (called "Pilot Excuses" or "Pilot Decisions" something like that) at JFK a few months ago where the presenter (Frank) asked who leans during taxi and most people raised their hands. When he asked why, some said because that's what they were trained to do. He then asked if anybody had read the Lycoming manual, nobody had. He claims that in there it specifically states NOT to lean on the ground because it will do the exact thing you are trying to avoid, foul the plugs. He said this applies to Lycoming only.

Has anybody actually seen the manual state to lean on the ground?
 
orange said:
I attended one of those WINGS seminars (called "Pilot Excuses" or "Pilot Decisions" something like that) at JFK a few months ago where the presenter (Frank) asked who leans during taxi and most people raised their hands. When he asked why, some said because that's what they were trained to do. He then asked if anybody had read the Lycoming manual, nobody had. He claims that in there it specifically states NOT to lean on the ground because it will do the exact thing you are trying to avoid, foul the plugs. He said this applies to Lycoming only.

Has anybody actually seen the manual state to lean on the ground?
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Millions of cumulative hours of operating experience says differently. Remember, Lycoming is in business to sell cylinders, not save you money.
 
orange said:
I attended one of those WINGS seminars (called "Pilot Excuses" or "Pilot Decisions" something like that) at JFK a few months ago where the presenter (Frank) asked who leans during taxi and most people raised their hands. When he asked why, some said because that's what they were trained to do. He then asked if anybody had read the Lycoming manual, nobody had. He claims that in there it specifically states NOT to lean on the ground because it will do the exact thing you are trying to avoid, foul the plugs. He said this applies to Lycoming only.

Has anybody actually seen the manual state to lean on the ground?
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lol, our fleet of lycoming engines that are heavily leaned indicate otherwise. I'll base my decisions off that versus what some guy says.

I've flown behind lycomings that aren't leaned on the ground and have spent plenty of time trying to clear spark plugs after failed mag checks on them.
 
But he didn't actually show you the Lycoming citation that said that, did he?

Also, this idea that common carburetors ignore the lean knob is easily disprooven (or proven if there actually IS a carb that does that). Just idle and gradually pull the lean knob and see what happens. (in Lycomings and Continentals, the ones Ive flown, the rpms start dropping)
 
jesse said:
lol, our fleet of lycoming engines that are heavily leaned indicate otherwise. I'll base my decisions off that versus what some guy says.
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I'm with you on this one, Jesse. I'd love to see the Lyc doc that recommends taxiing full rich. Does that include while at high altitude airports? :hairraise:

-Skip
 
Skip Miller said:
I'm with you on this one, Jesse. I'd love to see the Lyc doc that recommends taxiing full rich. Does that include while at high altitude airports? :hairraise:
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Here's the page from the O-360 manual. For the record, I lean my O-360-A4M aggressively on the ground and have no temperature or plug fouling problems.
 

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Pilawt said:
Here's the page from the O-360 manual. For the record, I lean my O-360-A4M aggressively on the ground and have no temperature or plug fouling problems.
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I would guess they put that there because they could give a crap less if you have to clean your spark plugs every 50 hours or so. Instead they're worried about people leaning not enough, forgetting about it, then taking off while still leaned leading to either an issue with partial power or an issue with cylinders overheating.

Hence why I make sure people lean so much that if they tried to takeoff that way they wouldn't make it 10 feet.
 
Turningfinal said:
Lycoming also released this, stating you should run 50° ROP for optimum service life, at the same time showing a graph correlating 50° ROP with near peak CHT (and ICP) :lol: :lol:

http://users.kymp.net/kotkanik/documents/SSP700A.pdf
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I never understood taking operating advice contradictory to evidence (and physics) from someone that makes their biggest margin off selling you replacement parts.:dunno: Lycoming and Continental's operating advice has always appeared to me to maximize cylinder sales. Most people who operate "by the book" top mid time. Most people who are aggressive LOP go TBO. This is especially true with high HP big engines like a 421 or Cheiftain.
 
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jesse said:
I would guess they put that there because they could give a crap less if you have to clean your spark plugs every 50 hours or so. Instead they're worried about people leaning not enough, forgetting about it, then taking off while still leaned leading to either an issue with partial power or an issue with cylinders overheating.

Hence why I make sure people lean so much that if they tried to takeoff that way they wouldn't make it 10 feet.
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When they (Lycoming) do talk about keeping plugs clean (in the operating manual and a later SB), they focus on running the engine at 1800 rpm for 15-20 seconds right before shutdown. I'll admit I don't do this.
 
Sam D said:
When they (Lycoming) do talk about keeping plugs clean (in the operating manual and a later SB), they focus on running the engine at 1800 rpm for 15-20 seconds right before shutdown. I'll admit I don't do this.
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It's a nice idea, but not feasible in many parking areas. The neighbors in my hangar row would not appreciate the wind, dust and noise from an 1800 rpm runup. But if I did it, I'd lean aggressively then, too.
 
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Henning said:
I never understood taking operating advice contradictory to evidence (and physics) from someone that makes their biggest margin off selling you replacement parts.:dunno: Lycoming and Continental's operating advice has always appeared to me to maximize cylinder sales. Most people who operate "by the book" top mid time. Most people who are aggressive LOP go TBO. This is especially true with high HP big engines like a 421 or Cheiftain.
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Funny how people pick and choose what they want to follow in the manual.

In certain cases, they say follow the manual (when it suits them or matches their idea of what is right), and always seem to have a reason why the manufacturer suggests otherwise.


FWIT- Companies don't usually advise customers to run their equipment incorrectly, so they can sell them parts or completely new one when they break. I have never had Dell tell me to run my CPU at max output all day so it will burn out and they can sell me a new one.
 
orange said:
Funny how people pick and choose what they want to follow in the manual.

In certain cases, they say follow the manual (when it suits them or matches their idea of what is right), and always seem to have a reason why the manufacturer suggests otherwise.


FWIT- Companies don't usually advise customers to run their equipment incorrectly, so they can sell them parts or completely new one when they break. I have never had Dell tell me to run my CPU at max output all day so it will burn out and they can sell me a new one.
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Yes, business will never lie to you to increase their sales. As for the manual, yes, you put something in there that is obviously stupid, I will ignore your stupidity and get on with my life. If it's your equipment and you want me to burn it up, no worries, I'll do just that. If I'm footing the bill, I will do what my experience tells me works best.
 
GlennAB1 said:
Bent and McKinley seem to be authorities that agree.
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I have idled the engine while leaned for an over half an hour on a hot summer day at a ground elevation of about 5,500' and not have a cylinder overheat.

Why on earth would I idle it rich because some guy who wrote a book said that a cylinder may overheat?

I have also learned that if I forget to lean while idling that the plugs will foul.

What is the correct thing to do, go by what some guy wrote in a book or trust my experience?

Books are great. I've got stacks of them. They don't have all the answers.
 
I defy someone to idle a 152 full rich for 1/2 and hour after run up, then go take off. You'll have at least 3 fouled plugs, and that's a Lycoming.
 
Pilawt said:
Here's the page from the O-360 manual. For the record, I lean my O-360-A4M aggressively on the ground and have no temperature or plug fouling problems.
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I guess Lycoming has never heard of doing a full power run up at LXV. They can shove that page right where the sun doesn't shine before I wont do a "above 2200 on the ground" run up at that airport.

orange said:
FWIT- Companies don't usually advise customers to run their equipment incorrectly, so they can sell them parts or completely new one when they break. I have never had Dell tell me to run my CPU at max output all day so it will burn out and they can sell me a new one.
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I run multiple Dells at 100% CPU+ all day long. If the bastards broke because of that, Dell would be replacing them under warranty or not have me as a customer anymore. Poor analogy makes me think you're just trolling and looking for a poor example. At least pick something not designed to do what you're claiming will harm it.

Henning said:
I defy someone to idle a 152 full rich for 1/2 and hour after run up, then go take off. You'll have at least 3 fouled plugs, and that's a Lycoming.
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Amen. Pass the Tylenol.
 
denverpilot said:
I guess Lycoming has never heard of doing a full power run up at LXV. They can shove that page right where the sun doesn't shine before I wont do a "above 2200 on the ground" run up at that airport.




I run multiple Dells at 100% CPU+ all day long. If the bastards broke because of that, Dell would be replacing them under warranty or not have me as a customer anymore. Poor analogy makes me think you're just trolling and looking for a poor example. At least pick something not designed to do what you're claiming will harm it.




Amen. Pass the Tylenol.
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What makes it interesting is two are usually in on cylinder, and the other is bottom on the same side to make the much rougher.:lol:
 
Operating statistics tell the truth, not what someone thinks should work because it does on paper or on an engine stand.
 
The checklist in the POH for my Archer III says to lean for taxi, so I do so, aggressively.

I tried not leaning, and my mag checks got bad within 10 hours. When I lean on the ground, my mag checks are always spot on.

Anyone who simply does what someone tells them, or what some book or operating manual tells them, despite clear evidence to the contrary, is a fool. Life is all about experimenting to find what works best. Start with what advice you can find, learn to understand why, and then experiment to figure out what works for you. That formula is called progress.
 
I'm definitely in the lean while taxi group. Based on experience. I live at 5000' so its more important up here.
 
Leaning has not been emphasized in my training.

I was just looking in a 172R POH and instructions there for 'fuel savings procedures for flight training' states to lean at 1200RPM for max RPM and leave the mixture there till runup, then do that again till takeoff. It states that this procedure can save 5% on fuel and reduce spark plug fouling.

Would this max RPM method be considered aggressive leaning, or slight?
 
jimbilly said:
Leaning has not been emphasized in my training.

I was just looking in a 172R POH and instructions there for 'fuel savings procedures for flight training' states to lean at 1200RPM for max RPM and leave the mixture there till runup, then do that again till takeoff. It states that this procedure can save 5% on fuel and reduce spark plug fouling.

Would this max RPM method be considered aggressive leaning, or slight?
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I have the same question; I've always leaned for ground ops using this procedure of slightly revving to 1200 RPM, leaning for max RPM (which is quite aggressive, usually halfway out on the mixture control in a 172), and taxiing like that.
 
orange said:
He claims that in there it specifically states NOT to lean on the ground because it will do the exact thing you are trying to avoid, foul the plugs. He said this applies to Lycoming only.
?
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That seems odd, any engine run rich or lean exhibit the same thing, funny how it can only apply to one manufacturer...
 
tehmightypirate said:
I have the same question; I've always leaned for ground ops using this procedure of slightly revving to 1200 RPM, leaning for max RPM (which is quite aggressive, usually halfway out on the mixture control in a 172), and taxiing like that.
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I'm getting the feeling that the setting for max RPM at 1200 won't have any effect on the idler flow.
 
Rykymus said:
The checklist in the POH for my Archer III says to lean for taxi, so I do so, aggressively.

I tried not leaning, and my mag checks got bad within 10 hours. When I lean on the ground, my mag checks are always spot on.

Anyone who simply does what someone tells them, or what some book or operating manual tells them, despite clear evidence to the contrary, is a fool. Life is all about experimenting to find what works best. Start with what advice you can find, learn to understand why, and then experiment to figure out what works for you. That formula is called progress.
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Imagine that, conflicting advice in manuals for operating a Lycoming.:rofl:
 
1RTK1 said:
That seems odd, any engine run rich or lean exhibit the same thing, funny how it can only apply to one manufacturer...
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It can vary depending on exactly how you design the metering system, but in this case the point is invalid because the metering system is not deigned that way.
 
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