Anyone with an O-540 "NOT" lean on the ground?

kenjr

kenjr

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KenJr
I've read a **** ton on this subject. Our group doesn't want anyone to lean the O-540 in our Cherokee 235 on the ground. They had a partner a while back who burnt up 3 cylinders with aggressive leaning. I contend based on what I've read and people I've talked to, including my own CFI who is also an A&P and works on several Warriors/Archers at the school...that there's pretty much no way to damage a non-aspirated Lycoming with aggressive leaning on the ground.

I found this a while back on the interwebs and shared with the group, including the actual Lycoming document they reference here - but the club's A&P seemed to sum it up referring to the scavenging agent in LL fuel that needs heat to activate. A combo of leaning + running at ~1200 or so RPM at idle is what you need to make sure that you aren't lead fouling the plugs.

http://www.flying20club.org/documents/Leaning_Lycomings.pdf

We recently did some troubleshooting to figure out why our left mag was dropping out of tolerance. Turned out our A&P ending up re-timing to get them within 50 RPM of each other. However, we pulled the plugs and several on the bottom were lead fouled.

So, what say you - especially the A&P types who work on these planes and perhaps have even talked to folks at Lycoming. I haven't read anything directly from them that flat out says, pull the mixture - lean aggressive - idle at no less than 1000RPM, etc... Most of their guidance is on what to do leaning at various power settings for takeoff, cruise, etc...

Thanks in advance!
 
kenjr said:
I've read a **** ton on this subject. Our group doesn't want anyone to lean the O-540 in our Cherokee 235 on the ground. They had a partner a while back who burnt up 3 cylinders with aggressive leaning. I contend based on what I've read and people I've talked to, including my own CFI who is also an A&P and works on several Warriors/Archers at the school...that there's pretty much no way to damage a non-aspirated Lycoming with aggressive leaning on the ground.

I found this a while back on the interwebs and shared with the group, including the actual Lycoming document they reference here - but the club's A&P seemed to sum it up referring to the scavenging agent in LL fuel that needs heat to activate. A combo of leaning + running at ~1200 or so RPM at idle is what you need to make sure that you aren't lead fouling the plugs.

http://www.flying20club.org/documents/Leaning_Lycomings.pdf

We recently did some troubleshooting to figure out why our left mag was dropping out of tolerance. Turned out our A&P ending up re-timing to get them within 50 RPM of each other. However, we pulled the plugs and several on the bottom were lead fouled.

So, what say you - especially the A&P types who work on these planes and perhaps have even talked to folks at Lycoming. I haven't read anything directly from them that flat out says, pull the mixture - lean aggressive - idle at no less than 1000RPM, etc... Most of their guidance is on what to do leaning at various power settings for takeoff, cruise, etc...

Thanks in advance!
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My limited experience would suggest that those three cylinders were NOT burned out as a result of aggressive leaning on the ground, the engine simply isn't producing enough power on the ground. Airborne may be a different story. They're tough engines but improper leaning over an extended period of time, I would find those conditions more conducive to cooking some jugs. I'll hand this off to someone who can expand on all of that.
 
To be clear, I don't think anyone thinks that the cylinders were burned up on the ground. The guy was trying to save $$ on gas in the air and was leaning way to aggressively and that's what caused the problems (or he was leaning at full power, etc...). Although, I have heard a couple of the guys mention that it's not safe to lean it out aggressively on the ground as the engine could get to hot, etc... I just don't buy that...I don't see how that's even remotely possible. The EGT isn't going to lie to you when you're on the ground.

I contend they are being overly cautious and because Lycoming doesn't seem to check the box by saying anywhere that I can find that you should lean aggressively on the ground that they are playing it safe and saying leave it full rich...all the time except for the obvious situations like takeoffs at high DA and of course leaning at altitude.

I also see folks pull the mixture knob out an inch or so leaning on the ground. From what I've read, that basically does nothing. You have to pull the knob out to a spot where if you were to apply significant throttle the engine would stumble or die.
 
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kenjr said:
...They had a partner a while back who burnt up 3 cylinders with aggressive leaning....
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...and they've drawn this conclusion based on what? I think what you are faced with here is someone talking out their a$$. As a professional A&P mechanic I've learned over the years that the less I say the less chance people will discover that I don't know WTF I'm talking about. :wink2:
 
I think they're going to be paying a lot of money soon on other problems if no one is leaning on the ground. Especially if anyone is traveling to high DA airports on a regular basis. Not good. The A&P will make more money this year than last and just the fouled plugs alone will lower the dispatch rate significantly.
 
Well, honestly I think the guy just told them what he was doing and kinda fought them on what EGT's were acceptable, etc... It wasn't just a SWAG.

The other guys in the plane aren't idiots - far from it - and they've been pilots longer than me. I am not a professionaly trained mechanic but I've been working on my own cars for many years - so I'm not stranger to an engine. Yes, aviation engines are unique, I understand that what I know about automobile engines doesn't always translate.

That said, I'm just trying to learn - not rock the boat. But, I want our engine to perform optimally and just trying to get the best and right answers.
 
denverpilot said:
...the fouled plugs alone will lower the dispatch rate significantly.
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no dispatch rate here. I'm 1/4 partner in this plane - we own it. We're the only one's that fly it. One of the guys has been in the plane over 15 years.

My home airport is 800'. DA's even on really hot summer days are no higher than 4000'. None of us regularly travel to any airports higher than that.
 
kenjr said:
no dispatch rate here. I'm 1/4 partner in this plane - we own it. We're the only one's that fly it. One of the guys has been in the plane over 15 years.
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Everything has a dispatch rate. Put in different terms, "You'll be failing more run-ups and taxiing back not having gone flying that day, wasting your time, as you go spend it pulling spark plugs to clean them or paying the mechanic to do so."
 
I lean ALL my engines very aggressively on the ground! At the very low power settings during taxi it is impossible to hurt an engine. The benefit is a near total elimination of fouled spark plugs. To give you an idea how far I lean, the engine must be richened to do a run up before take off. Mixture rich becomes a mandatory take off check.
 
Computerjim said:
I lean ALL my engines very aggressively on the ground! At the very low power settings during taxi it is impossible to hurt an engine. The benefit is a near total elimination of fouled spark plugs. To give you an idea how far I lean, the engine must be richened to do a run up before take off. Mixture rich becomes a mandatory take off check.
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:yeahthat:
 
Pretty hard to damage them if you're below 65% power so leaning during taxi is no factor. My guess, and I can't confirm it without seeing an engine monitor trace, is that one individual is leaning it right into what George Braly's crew terms "the red box" creating both high CHT's and EGT's. That's guaranteed to toast cylinders.

Running it full rich at idle just keeps your A&P employed.
 
He didn't burn up three cylinders by leaning too aggressively. If anything, he burned them up by not leaning enough on that engine. I'd also guess that the cylinders were old, overhauled a time or two, and/or not factory Lycomings. I see some people on carbureted engines who will not lean enough because they don't like the hair of roughness they may get.

I don't lean on the ground because it's never caused me an issue. My plugs haven't fouled, the extra fuel consumption is irrelevant, etc. I have flown planes where it matters, and it seems carbureted engines usually benefit more from it, probably due to poorly balanced fuel distribution. I haven't flown a carb'd engine in years.
 
While this is a Lycoming, Continental pretty much says you can set the mixture anywhere from full rich to so lean the engine is misfiring as long as you're below the max recommended cruise setting. On a carb'd engine at (near) idle, I doubt you can do anything. The mixture control really isn't having any effect on the idle loop until you get near cutoff anyhow.

The number one killer on engines is HEAT. That's more and more coming out while the experts fight the ECI AD that's proposed. Over leaning at high power settings in low speed (climb) procedures is more detrimental than cruise LOP or even shock cooling on approach.
 
I flew behind an O-540 for 11 years. The only time I didn't have to lean aggressively on the ground was when I was running that sweet unleaded mogas. Man, I miss those days -- that engine LOVED car gas.

If I didn't lean when running avgas, I fouled the bottom plugs, every time.

This problem was greatly reduced by installing fine wire spark plugs, but those things cost a freaking fortune. It's far cheaper to simply lean aggressively on the ground.
 
kenjr said:
The other guys in the plane aren't idiots - far from it - and they've been pilots longer than me.
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There are lots of pilots that have no idea how the combustion cycle works. I would continue your effort in assembling literature about the subject to educate them.

As others have said, the engine can be leaned to the point where it barely runs during ground ops and that will not harm it.
 
3393RP said:
There are lots of pilots that have no idea how the combustion cycle works. I would continue your effort in assembling literature about the subject to educate them.

As others have said, the engine can be leaned to the point where it barely runs during ground ops and that will not harm it.
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I've seen this before. Sad outcome is that the OWTs are entrenched and nothing short of expert v expert will sway them to at least give a few brain cell's worth of consideration.
 
Computerjim said:
I lean ALL my engines very aggressively on the ground! At the very low power settings during taxi it is impossible to hurt an engine. The benefit is a near total elimination of fouled spark plugs. To give you an idea how far I lean, the engine must be richened to do a run up before take off. Mixture rich becomes a mandatory take off check.
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That's my understanding too and I run my IO540 accordingly.

Perhaps damage might stem from leaners forgetting to go full rich before takeoff.
 
I lean everything on the ground as aggressively as I can. It's habit. I start, verify oil pressure, and lean.
 
Bill Watson said:
That's my understanding too and I run my IO540 accordingly.

Perhaps damage might stem from leaners forgetting to go full rich before takeoff.
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If you lean the engine enough to actually do something useful for at idle in most planes (especially the carb'd engines), it will stumble badly when you cram the throttle full in for takeoff (or even to the point of the power setting most of us use for run ups).

The problem occurs with the guy who pulls the thing out a inch (or a few turns on the vernier) thinking that does something. It turns out to not do anything to really lean the setting at idle and the engine will appear to happily run at full power with that setting if he forgets to put it back to full rich on takeoff. Couple this with the further believe that he shouldn't climb out at full power (but above a sane continuous rate) then you defeat the lycoming economizer setting on the carb that enrichens the mixture at WOT. You end up with the WORST situation, lean situation at high power, very high cyinder and exhaust temps and minimal engine cooling from airflow (high AOA). Everything he's done is exactly the WRONG thing to do for the engine.
 
If you don't lean aggressively on the ground you will go through spark plugs like nobody's business and you'll have poor mag checks almost every runup. I lean extremely aggressively on the ground, if I cram in full power it's not going to stay running so takeoff enriching is no issue.
 
flyingron said:
If you lean the engine enough to actually do something useful for at idle in most planes (especially the carb'd engines), it will stumble badly when you cram the throttle full in for takeoff (or even to the point of the power setting most of us use for run ups).

The problem occurs with the guy who pulls the thing out a inch (or a few turns on the vernier) thinking that does something. It turns out to not do anything to really lean the setting at idle and the engine will appear to happily run at full power with that setting if he forgets to put it back to full rich on takeoff. Couple this with the further believe that he shouldn't climb out at full power (but above a sane continuous rate) then you defeat the lycoming economizer setting on the carb that enrichens the mixture at WOT. You end up with the WORST situation, lean situation at high power, very high cyinder and exhaust temps and minimal engine cooling from airflow (high AOA). Everything he's done is exactly the WRONG thing to do for the engine.
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:yesnod: :yeahthat:
 
flyingron said:
If you lean the engine enough to actually do something useful for at idle in most planes (especially the carb'd engines), it will stumble badly when you cram the throttle full in for takeoff (or even to the point of the power setting most of us use for run ups).

The problem occurs with the guy who pulls the thing out a inch (or a few turns on the vernier) thinking that does something. It turns out to not do anything to really lean the setting at idle and the engine will appear to happily run at full power with that setting if he forgets to put it back to full rich on takeoff. Couple this with the further believe that he shouldn't climb out at full power (but above a sane continuous rate) then you defeat the lycoming economizer setting on the carb that enrichens the mixture at WOT. You end up with the WORST situation, lean situation at high power, very high cyinder and exhaust temps and minimal engine cooling from airflow (high AOA). Everything he's done is exactly the WRONG thing to do for the engine.
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Good point. People need to understand how to lean and lean aggressively for ground ops. Being cautious can create problems.
 
Do 0-540's run that much different than 0-360 concerning leaning on the ground?
I have flown my Cherokee with 0-360 almost 500 hrs and have never leaned on the ground. I have never fouled a plug, not once. I use REM-38E;s for plugs
I don't start leaning in the air till about 5,000 ft.
Other than maybe burning some extra fuel what am I doing wrong?:dunno:
 
The O-540 in the 235 seems to be among the worst at fouling plugs on ground. I have an engine monitor and mine has fouled both plugs in a cylinder more than once (no temp). As others have said...if you don't lean it soon after starting you will never get a good mag check.
 
So, what are folks - once again with the O-540 - doing on the ground to warm up the engine prior to the runup now that it's cold? I live in Austin, TX so we're not talking 'THAT' cold - worst will be at or above freezing and our plane is hangared so it won't get the worst of it. When I had just started my PPL this time last year my CFI (also the school's A&P) would idle us around 1200RPM and we'd lean aggressively on the ground to get the temps up in the cylinders. Once the temp gauge needle would start to move we'd do the runup. These were in Warriors and Archers which probably have the 360 or something similar. We did basically the same thing once I bought into the 235 and we were flying that.

I had a few out of tolerance mag drops but we were able to burn it off at runup.

I know the other guys don't lean at all on the ground - not even after a low power or power off approach when they are taxiing in. It makes total sense to me to lean on the ground - can't figure out why you WOULDN'T do it? I'm sure the fuel savings isn't all that significant but I can't imagine you can get the engine near hot enough to cause any problems on the ground.
 
el con said:
Do 0-540's run that much different than 0-360 concerning leaning on the ground?
I have flown my Cherokee with 0-360 almost 500 hrs and have never leaned on the ground. I have never fouled a plug, not once. I use REM-38E;s for plugs
I don't start leaning in the air till about 5,000 ft.
Other than maybe burning some extra fuel what am I doing wrong?:dunno:
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Depends on the engine, some are quite happy to run rich on the ground some won't make it to the runway on the first run after a plug cleaning full rich. The 360-C1C on our arrow has never fouled a plug to my knowledge but the L2A in our 172R MUST be leaned during the summer months or it will fail the mag check almost every time.

That said, ground leaning won't hurt (just take off rich) so I just do it.
 
Lycoming says that once you can advance the throttle without the engine stabling, you've warmed it up all that it needs.
 
flyingron said:
Lycoming says that once you can advance the throttle without the engine stabling, you've warmed it up all that it needs.
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They also publish max cht temperatures that are scary hot. At the end of the day, limits are not goals, and a good engine preheater is going to go a long ways towards getting things heated up in a way that will extend engine life.
 
jesse said:
They also publish max cht temperatures that are scary hot. At the end of the day, limits are not goals, and a good engine preheater is going to go a long ways towards getting things heated up in a way that will extend engine life.
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I didn't say preheat didn't help. I was arguing that extended "warm up" periods on the ground do no good and the manufacturer doesn't recommend them.
 
jesse said:
They also publish max cht temperatures that are scary hot. At the end of the day, limits are not goals, and a good engine preheater is going to go a long ways towards getting things heated up in a way that will extend engine life.
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:yes:

flyingron said:
I didn't say preheat didn't help. I was arguing that extended "warm up" periods on the ground do no good and the manufacturer doesn't recommend them.
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The oil temp is also supposed to be in the green before takeoff, which is important. Sometimes, that does require sitting a bit. My experience is that the engine almost never stumbles upon throttle advance, no matter how cold.

Most of the time, a standard start-up, avionics on, weather, taxi, run-up, etc. will be enough time to get the engine warmed up enough.
 
el con said:
Do 0-540's run that much different than 0-360 concerning leaning on the ground?
I have flown my Cherokee with 0-360 almost 500 hrs and have never leaned on the ground. I have never fouled a plug, not once. I use REM-38E;s for plugs
I don't start leaning in the air till about 5,000 ft.
Other than maybe burning some extra fuel what am I doing wrong?:dunno:
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I did 1500 hours on an O-360 in a Maule. When I didn't lean aggressively and consistently on the ground, my oil would turn black in <5 hours after a change. It only occasionally (once or twice a year) fouled during taxi resulting in a 'failed' mag check and requiring 'clearing' before takeoff.

Once I began aggressively and consistently leaning for ground ops, my oil stayed clear much longer (not sure whether that is significant or not) and I never experienced fouling or a failed mag check.

With the IO-540, I lean aggressively and all is well so far at 350 hours.
 
Just a point: When you have a fuel monitor you can see that thje difference in fuel consumption at idle is noise. Oh. Maybe 2.5GPH-1.75GPH.

But I do lean with the Levy/Lycoming method as soon as the engine is running smoothly. I've never managed to take off with the engine leaned. The coughing is too distracting.

I had chronic problems with plugs fouling but that went away once I got the engine topOH'd. It was oil fouling to a large extent.
 
flyingron said:
The problem occurs with the guy who pulls the thing out a inch (or a few turns on the vernier) thinking that does something. It turns out to not do anything to really lean the setting at idle and the engine will appear to happily run at full power with that setting if he forgets to put it back to full rich on takeoff. Couple this with the further believe that he shouldn't climb out at full power (but above a sane continuous rate) then you defeat the lycoming economizer setting on the carb that enrichens the mixture at WOT. You end up with the WORST situation, lean situation at high power, very high cyinder and exhaust temps and minimal engine cooling from airflow (high AOA). Everything he's done is exactly the WRONG thing to do for the engine.
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:idea:
Why do many C/S prop airplanes' climb procedure include throttle reduction immediately after liftoff?
Perhaps this thinking is part of the problem?
 
Jaybird180 said:
:idea:
Why do many C/S prop airplanes' climb procedure include throttle reduction immediately after liftoff?
Perhaps this thinking is part of the problem?
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Mine doesn't. You pull the power for noise abatement and in my case not to bust right through pattern altitude on pattern work and later keeping under the Bravo.

You can't spend a lot of time climbing at 2000FPM and not hit the Bravo. :rolleyes: :D
 
mikea said:
Mine doesn't. You pull the power for noise abatement and in my case not to bust right through pattern altitude on pattern work and later keeping under the Bravo.

You can't spend a lot of time climbing at 2000FPM and not hit the Bravo. :rolleyes: :D
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The 3 I've flown do: C182, DA40, M20 all ask that you reduce throttle and reduce RPM in the climb. IIRC Arrow does too.
 
Jaybird180 said:
The 3 I've flown do: C182, DA40, M20 all ask that you reduce throttle and reduce RPM in the climb. IIRC Arrow does too.
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Yeah, they do to generally reduce power output and be kinder to the engine. Is it truly necessary? Not usually. And I've not always done it, it depends on the needs of the moment. When climbing through ice or in high terrain areas I've been known to climb at max continuous as long as I feel like it. In the Aztec my general procedure was firewall for takeoff and leave it there. Throttles didn't come back until it was time to land.
 
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