Re: Ground leaning

Re: Re: Ground leaning

Yes, John.  ThetaPP is the point of crankshaft rotation(theta) in degrees at which the cylinder experiences the highest internal pressure (PP = peak pressure).  We know that the peak pressure occurs at the point where 50% of the gas charge has been burned.

The understanding of Theta PP is crucial in undestanding what stresses are being put on an engine.  For example, an engine with a ThetaPP of 16dATDC will produce MORE power and under less stress than the SAME engine at the SAME MP and RPM with a ThetaPP of 11dATDC.

We have come to appreciate that ThetaPP coupled with the peak internal cylinder pressure are the two most important things to know in any engine.  At this point, the only people who can measure these events in real time on a running engine are at the Carl Goulet Memorial Engine Test Facility oin Ada, OK.  We use this facility when we teach the Advanced Pilot Seminars.

Walter Atkinson
Advanced Pilot Seminars

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Re: Re: Ground leaning

*ThetaPP = theta prime*

Not in this instance.  See my previous post explaining the engineering term of ThetaPP.

Walter

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Re: Re: Ground leaning

OK, Glenn.  What YEAR was your engine built?

Walter

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Re: Re: Ground leaning

Well, I must say Walter, you don't give up your own opinions too easily!  But I feel that your own arguments are what help to prove your errors. 
Example: You wrote: "You know, this is so WRONG it's hard to respond to. It's very misleading. The above statement relates to takeoff power, not idle, low-power mixtures and the statement is really misleading. It is WRONG." 
Response: But Walter, it is YOU who is suggesting to lean aggressively to the point of LOP during run-ups, and in the previous post, to advocate aggressively lean mixtures for high-altitude takeoff power. 
  It is exactly the technique you espouse, ...namely that of leaning aggressively for takeoff ... that you've also agreed with the mfr's may CAUSE that detonation!  It is the very condition which TCM is advising AGAINST that you seem to be promoting.

You state ""Too lean" and "not rich enough" are NOT the same thing."   (Are we both speaking ENGLISH?)
  Walter, I am comfortable in “not rich enough” being equated to “too lean”.  You call it what you like,…the damn thing needs more fuel and the way to achieve that is push the mixture control forward.

You also wrote: "If one were to experience detonation, one of the quickest ways to STOP it is to turn one mag OFF. That causes the ThetaPP to be retarded, which retards the "effective ...blah blah blah..."
  Walter, that would be true IF the cause of detonation were inflight mag-failure such as if the plastic mag distribution/rotor gear were stripped and stopped turning.  (A common failure of mags, by the way.)  In such a case, a 6-cylinder mag dist/rotor would stop turning but the mag would still be generating 6 plug firings to whichever plug it was pointed at, when only ONE of those sparks were being delivered at the correct TIME for that cylinder.  In other words, that cylinder which received all 6 sparks would get ONE spark at the correct moment of firing, while the SAME cylinder would get FIVE MORE sparks at the WRONG moment, such as when the piston might be travelling upward, just BEGINNING a compression stroke, where such a spark might SERIOUSLY overstress that piston and connecting rod.  (Would you be willing to agree that would likely deliver the symptoms of detonation to the cockpit occupant?)
  Switching to the good mag would certainly kill the bad one and would instantly cause the engine to run smoothly again.  Switching to the bad mag would cause the engine to either quit completely or at the very least run so rough as to scare a deaf mule. 
  But that situation has NOTHING to do with mixture.
  Your recommendation to go running around at high power settings, already aggressively leaned near or beyond max EGT's, and then switch to one magneto just for the fun of doing so, endangers the public.  (Most mfr's would have a rough-running engine FIRST enrichened, THEN a magneto check.)

  In your own words, you agreed that a too-lean mixture,  ...er excuse me,...a "not rich enough" mixture... would cause detonation at takeoff power.  Exactly how do you define takeoff power?  Isn't that full throttle, max power available (at least in most recip engines)?  Now, correct me if I'm wrong, but the last time I flew a 172, 182, or 206, or ...go ahead, you name any normally aspirated reciprocating engined airplane, ...above about 7500 feet, the throttle WAS wide open!   That was exactly the same condition that one might encounter during the high-altitude takeoffs we discussed earlier in this thread! (The one you disagreed about.)

You can call it ThetaPP or any other thing you like, but the reason I asked you if you'd ever looked at your EGT while you (foolishly, in my opinion) did mag checks while running high power settings in cruise was to draw your attention to the fact that while you are advocating this LOP operation for RUN UPs, ...you are actually (and erroneously, in my opinion) performing that run up operation while in cruise flight! (Wrong time, wrong place.)  The REASON your EGT's increased when you switched to to one mag is (we agree) because some of those combustion mixtures are now being burned in your exhaust system, and NOT in your combustion chamber, and it is being noticed by your EGT probe.  Not only is that the wrong place for combustion to be occuring, it's hard on your exhaust, your exhaust turbocharger (which in turn influences your induction manifold pressure) encouraging detonation.  If you think your procedure doesn't place your exhaust system at risk you are mistaken.
 
  When I talk about  leaning to the point of backfire, I said exactly what I meant.  You say you have radial engine experience.  Have you never gotten rid of carburetor ice by leaning to the point of backfire?  Never heard of it?  You need to go talk to some old DC-3, Convair, and Martin pilots.  It was common knowlege among all the old-timers as a way to clear iced carbs in the early radial engined airliners.  The drawback to the procedure was the chance of causing damage to the induction system due to the backfire, but if a pilot had let carb ice develop to the point of losing power and available carb heat, and couldn't risk further loss by application of carb heat (perhaps due to carb temp indicator failure in the case of the Martin), leaning to the point of backfire was a well-known technique.  (I only used it colloquially in the previous posting, but the technique was valid and real.  I know.  The first multi-engine time in my logbooks is DC-3 time logged as copilot for Avion, an early competitor of Trans Texas Airways (predecessor to Continental Airlines.)

  Anyway, how 'bout we focus on what we DO agree upon.  Leaning during ground ops (not exactly a life-threatening place), in CERTAIN airplanes is good for keeping plugs operating cleanly.  Cruising LOP is OK and can save money in CERTAIN airplanes that have proper fuel distribution (fuel injection for example) and INSTRUMENTATION (such as a good quality, all-cylinder analyzer).
    Which brings me to the question Walter asked earlier, "What is the difference in the physics of combustion in carbureted vs injected engines? The cylinder, air, and spark don't know how the fuel got there."   Walter, this has got to be one of the defining moments of your misunderstanding of this subject.  The difference is this:  Fuel injected engines have fuel systems more sophisticated, more capable of careful fuel metering and more capable of delivering an accurate/consistent measure of fuel to each cylinder.  They deliver their fuel via calibrated injectors directly at the induction point of each cylinder from a local source of fuel pressure, the so-called "spider" or fuel manifold.  This gives each cylinder a nominally identical fuel charge.  They do it without having their mixtures varied by any chance of carb-ice build-up which might richen such mixture. (Even within fuel injected engines however, there are small differences between cylinders for induction reasons common with carbureted engines.)  Carbureted engines have a much cruder system.  The carburetor is located farther away from the cylinder intakes, where it more crudely sprays fuel into the moving induction air with longer pipe distances to traverse before it gets to the cylinder.  Some of those pipes deliver that fuel to the cylinder in such a short distance it may still contain raw fuel or overly rich mixtures, while other cylinders may get much leaner mixtures due to induction pipe/hose leakage, twisting/turning pipes, etc.   Such engines simply can't be run with cylinders receiving sufficiently accurate and homogenous mixtures to recommend LOP operations except perhaps on just a few cylinders.  If some cylinders are LOP, that means others are running richer, possibly IN THE VERY RANGE OF DANGER that proponents of LOP operations caution about. 
  Since cruder fuel delivery and cruder instrumentation is what most of these simple, carburetor-engined airplanes consist of, it seems irresponsible to me to  recommend such advanced operating techniques categorically to everyone who flys. 

  I'll give you a big gold star for being suspicious of some mfr-issued documents.  Many of them in recent years are written by the legal department.  (King Air takeoff checklists have the pilot arm both the autofeather (which is designed to feather the prop instantly in case of failure) and the auto-ignition system (which is designed to do an instant re-start in case of failure) simultaneously on each takeoff.  I can't think of anything I'd hate to do more while struggling to remain airborne and in directional control a few feet above the freeway traffic near the airport, than light off an engine that 1) has it's propeller feathered 2) has it's throttle wide open 3) and has it's combustion chambers and exhausts full of atomized fuel.  Talk about fire/explosion hazard!)  But those lawyers are doubtlessly convinced they've covered every emergency.
  But ...as Walter says, the gasoline, piston-engine development hasn't changed a whole lot in recent years, so the procedures that have worked for the last 60 years are also STILL VALID!


  Bottom line: (I'm pretty certain Walter and I will not see ourselves in agreement in an online discussion, as this is simply not the kind of media to discern the finer points of our differences.  He and I may simply be gnashing our teeth over minor misunderstandings, or we may truly have widely diverse opinions.)  I personally wish to caution everyone who has been following this discussion that not every advanced procedure is appropriate in all engines/airplanes just because it may work in some of them.  Moderation in all things.  (And don't try it with engines not properly instrumented.)  The fuel is cheaper than the engine, is only an OWT when the price of oil goes up a whole lot more than it is lately.

   
   (And Walter, It matters not who one works with.  If one learns it wrong, applies it wrong, or simply tells it wrong, it's still wrong.  Let's get together.  I'll buy the first round.)  ;Þ

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Re: Re: Ground leaning

George:

Well, isn't this going to be fun?  It's cut and paste time again. <vbg>

I don't give up on my opinions because they are so strongly backed by the laws of physics.

<it is YOU who is suggesting to lean aggressively to the point of LOP during run-ups, and in the previous post, to advocate aggressively lean mixtures for high-altitude takeoff power.  >

Yes I do recommend aggressive leaning for run-ups.  At the very low powers of run-up, nothing is at risk at ANY mixture setting.

I have NEVER recommended taking off at aggressively leaned mixtures.  If you got that out of anything I said it was a miscommunication.  I know that about 250dF ROP is a good, safe mixture for max power.  That certainly is not leaned for takeoff.  At a high altitude airport, one must lean to that mixture to not be overly rich and lose too much power.

<It is exactly the technique you espouse, ...namely that of leaning aggressively for takeoff ... that you've also agreed with the mfr's may CAUSE that detonation!>

I have NOT recommended that.  Period.

<You state ""Too lean" and "not rich enough" are NOT the same thing." >

They are simply NOT the same.  Don;t feel like the Lone Ranger.  This is a very common mistake and one which leads to a lOT of misunderstanding.  Being, say 100dF ROP for takeoff is waaaay not rich enough at sea level.  It is NOT too lean.  It is NOT a lean mixture at all and to reference it as too lean is misleading.  Rich mixtures are those in which there is more fuel than is burned by the available air--by definition, we call that a rich mixture.  A lean mixture is one in which there is more air than can be used by the available fuel.  I have taken off in what we call a FTLR engine (full time lean run) in which the mixture is never rich of peak EGT at any time.  It is LEAN.  Mixtures with extra fuel are RICH.  Mixtures with extra air are LEAN.  It is not possible, by proper defintion for ANY mixture rich of peak EGT to be too lean.  It is not rich enough.  That is a VERY important distinction and if you are not familiar with it, we cannot discuss these issues at all.  This is a very basic concept which we find many people do not understand.  Yes, we are both speaking English, but we clearly are not both using the same engineering defintion of terms.  To properly communicate, we must do that.

50dF ROP is not a lean mixure.  It is a RICH mixture. It is not too lean... it is not rich enough.  Lean MUST refer to mixtures LOP.  Otherwise we cannot discuss these issues with clarity.

<I am comfortable in “not rich enough” being equated to “too lean”.  You call it what you like,…the damn thing needs more fuel and the way to achieve that is push the mixture control forward.>

I hope I've set that issue to rest.

You spent a lot of time explaining some weird mag problem which cause detonation and it has nothing to do with this converstaion.

Here's an example.   You are applying takeoff power and as a result of a very high CHT and maybe inadequate fuel flow (not rich enough?), detonation starts.  You understand how to recongnize this on your engine monitor as detonation and you have a choice.  You can immediately reduce power and hit the trees at the end of the runway or you can turn one mag off and continue to fly at max power.  By turning one mag off, the flame front will be slower by 50%. This retards the effective timing.  This reduces the ThetaPP dramatically. This reduces the pressure inside the cylinder and STOPS the detonation event. However, the engine continues to produce power and the airplane fly.

With all due restect, if you are unfamilair with the terms, of ThetaPP or *effective* timing, we will have some difficulty in the discussion.

As a DC-3 guy myself I know about leaning to backfire ice out.  That was not what you said.  You said I would backfire the exhaust off the airplane by doing a lean of peak, high power mag check.  I stated that that would NOT be a backfire.  You are discussing true backfire now.  INTO the carburetor; not into the exhaust.  It is NOT POSSIBLE to have a backfire out the exhaust.  I have been doing in-flight mag checks for a long time.  You need to see one.

George, you went through some long explanation about how injected engines and carbed engines are different, then said, "Such engines [carbureted] simply can't be run with cylinders receiving sufficiently accurate and homogenous mixtures to recommend LOP operations except perhaps on just a few cylinders.  If some cylinders are LOP, that means others are running richer, possibly IN THE VERY RANGE OF DANGER that proponents of LOP operations caution about."

With your level of unsderstanding on this issue and the level of understanding I used to have, I would agree.  The problem here is that WE both were making a WRONG assumptin for 40 years.  I CAN and DO run carbureted engines LOP.  I have fiugured out how to do that by getting ALL of the cylinders to have the SAME F:A ratios--yes, in a carbureted engine also.  You would admit that IF one could get all of the cylinders to get the same F:A ratios that this would possible, right?  Well, contrary to what WE thought for a long, long time, I am doing that.  It turns ou that the carberetur is not as crude as we thought and that it CAN be a very nice way to get fuel evenly distributed.  I would think that fact that this has just recently been discovered (last Feb.) would peak your interest in learning how.

<<Since cruder fuel delivery and cruder instrumentation is what most of these simple, carburetor-engined airplanes consist of, it seems irresponsible to me to  recommend such advanced operating techniques categorically to everyone who flys. >>

It is important to have proper instrumentation.  It is not my position that "all of the pilots we're talking to on this forum are too stupid to do this for themselves and they should not be informed of what is possible because they might hurt themselves."  On the contrary, I think pilots are smart folks.

<But ...as Walter says, the gasoline, piston-engine development hasn't changed a whole lot in recent years, so the procedures that have worked for the last 60 years are also STILL VALID!>

Well, the PHYSICS hasn't changed, but our understanding of it sure has. And there is a lot of misunderstanding out there which has made 60 years worth of old wive's tales pretty hard to kill.
     
<Let's get together.  I'll buy the first round.>

Now there's a hell of a good idea.  I'll buy the second round.. but not before we go fly.  I want you to SEE some of these things you have not seen before.  Where are you based?  I'm in Baton Rouge. Let's do it.  Why not?

Walter Atkinson
Advanced Pilot Seminars

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Re: Re: Ground leaning

George:

Would you be so kind as to call me... or e-mail me a # where I can reach you?

Thanks.

Walter
< This e-mail address is being protected from spambots. You need JavaScript enabled to view it >
office (225) 925-2066
cell (225) 939-7508

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Re: Re: Ground leaning

I'm a Cessna owner that found this place just a few days ago, and I thought it might be a nice place to share and learn, then.....
Walter and George dukin it out on the internet.

Come on guys, people like me could care less how many degrees you hold, or how intelligent you can prove yourself to be.  And the posting of these book length messages is a real show of your intelligence.   It's like watching two bullies on the playground.  I'd be willing to bet one of you doesn't shower cause you don't stink.  Grow up.

I'll be moving on now, to a place more suited for ignorant people like me.

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Re: Re: Ground leaning

So then...Mr. Horn and Mr. Walters, what is your consensus about ground leaning...in as few word as possible? 

Give us a combined takeaway that is useful, relevant and consistent...to set straight the loudmouths and common fallacies!

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Re: Re: Ground leaning

     I find this to be a fascinating subject and have enjoyed the spirited cross-fire. So far I've been able to interpret some very key points....everything the manufacturers teach is bunk and, hey, for a price, I can learn the "Real and Only" method for keeping my engine alive. Well folks, I've been working on airplanes for a long time and whenever someone tries to sell me on the "Best" product or method I smile and continue to do what works for me and my customers.
   As far as ground leaning I'll have to agree with George....the idle mixture is metered ONLY by the idle mixture adjustment.....the mixture control acts only as a crude shut-off....and that's for carbureted or injected engines. Since our topic was ground leaning and not take-off, flying LOP vs. ROP in cruise etc. and the proper interpretation of graphic engine monitors in the quest for max power/best fuel flow I'll defer to the experts to start another topic covering that info.
   Now, I'll soak my feet in Marvel Mystery Oil and wait for more sparks to fly :^)

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Re: Re: Ground leaning

As I said in the very early messages on this topic:

Agressive ground leaning does several things. 

1) it keeps plugs from fouling.

2) it keeps the piston head and valve heads from picking up deposits.

3) A ground leaned mag check is MUCH more diagnositc of ignition problems than a Rich mag check.

4) a properly, aggressively leaned engine on the ground will have lower CHTs prior to takeoff power being applied.

There are NO known downsides to agressively leaning on the ground.  Leaning inadequately is not good.  Be very aggressive.  So much so that it won't take power without dying.  Since praticing this, I have not had a fouled plug (in ten years) and I have picked up weak plugs many times which passed the full rich mag check.

Walter Atkinson
Advanced Pilot Seminars

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Re: Re: Ground leaning

<As far as ground leaning I'll have to agree with George....the idle mixture is metered ONLY by the idle mixture adjustment.....the mixture control acts only as a crude shut-off....and that's for carbureted or injected engines.>

That statement is simply not in harmony with the known observations.  I would be more than happy to SHOW you and prove that you can ground lean carbureted engines as well as injected engines.  There are hundreds of people doing it as a matter of routine.  Below is a note from a Beech owner off of the Beechlist on some of what we have been discussing in this topic in which it was stated that running on one mag caused detonation:

*****

Shut off one mag in flight and watch the EGTs rise 80 degrees.  At the same time you'll see the CHTs fall and you'll lose some airspeed.  If you get a nice rise on all six cylinders on each magneto, you can be confident that your ignition system is working great,  and you'll realize that your EGTs are much cooler than you ever thought before.

You might want to consider signing up for the Advanced Pilot Seminar where you can get a thorough immersion in these topics.  I got a lot out of the course myself.

Jonathan Fuller

*****

There are hundreds of people aggressively ground leaning (I've been doing it for many years on both carbureted and injected engines) and if it isn't possible, how is it working?

Confusious say, "Don't tell man already doing something that it impossible."

As for selling knowledge...  I don't think I'll respond to that.  You certainly don't have to learn.  The FAA thinks enough of our course that it is authorized for 100% of the annual renewal of the IA Certificate.  The FAA engine directorate is paying attention.  Numerous overhauls shops' owners have attended. Many pilots are flying as we teach.  Anyone can be left behind.  Will you be one of them?  Ain't America great?  It's your choice.

Walter Atkinson

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Re: Re: Ground leaning

I am talking about operations at IDLE....no other power setting...if you have to compensate with aggressive mixture at idle you've got other problems....the least of which is a misadjusted idle mixture and possibly excessive idle fuel pressure on TCM fuel injection. In Arizona my customers get idle checks and adjustments twice a year at a minimum...on newer Cessnas that's mandatory.   I'm sure you are familiar with the idle circuit in the fuel system...so tell me what your RPM rise should be with mixture full rich at idle.
As for the FAA thinking enough about your program to give me credit for IA renewal......I can get that free here because I do this for a living...approximately 20 annuals per year and countless major repairs, conversions and mods. I'm not dismissing your program and I'm sure I would learn a bunch there...I learn at every school I attend. I'm just not on this list to troll for business.

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Re: Re: Ground leaning

Gregg:

While I'm not on this list to troll for business either, many people ask me how I know and where do I get my information and data.  I tell them.  I'm not embarrased about that.  I also am on this list to impart knowledge and gain some.

You asked me a question about rpm rise.  I assume you mean idle mixture rpm rise on shut down?  25-50 rpm is generally recommended.  That's where I generally set mine.  That is not at all what I'm taking about.  Here is another post from another Cessna Board from someone who is properly ground leaning.  I'm not the only one. Notice he's doing this in an injected AND a carbureted engine?  How is he doing this if it's impossible?

*****

I concur with the taxi leaning mentioned...lean until it stumbles, then richen enough to let you taxi...I do this on the 210 and 172 and never get fouled plugs...I even do this at sea level...plugs foul anywhere.  I believe the press that the power setting at taxi is too low to hurt the engine, and the mixture is too lean to let one start a takeoff without remembering to enrichen it...engine won't run at higher than taxi speed if it's leaned down far enough for a foul-free taxi.

I've found the position of the mixture knob seems to vary some every time it's worked on...so leaning to a particular length extending from the panel will vary from plane to plane, or repair to repair, it seems.

--Carl Gilbert

PS: Buy a multi-probe egt/cht, right away!  We've got an Insight on our 210, I hear the JPI's are really good too.  Buy it before you buy anything else.  Today.  Hang up the modem and run buy one.  Go!  Shoo!     

******

Data R Us.

Walter Atkinson
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Re: Re: Ground leaning

Another note from that *other* Cessna board. On a carbureted engine, no less.

Walter

*****

I try to lean out the engine as soon as possible after starting.  Like everyone else, I lean until it stumbles then richen just enough to keep it running. 

The interesting thing I discovered is that if I'm starting up the engine when it's cold (and by cold I don't mean 35 degrees out, I just mean not a hot start), once the engine warms up a bit, I can lean it further.  So for example, I might be able to lean it out 3" after start up, but by the time I taxi to the runup area on the other side of the airport, I can lean it out another inch or so.

Whoever came up with that ground leaning advice really did good.  I've never had a fouled plug in 900 hours of Skylane flying.

--Ron

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Re: Re: Ground leaning

Walter,
   If, at normal operating temps, the idle mixture is set correctly, the idle rpm is set correctly and boost pressures and altitude compensation are on the mark you don't need to pull the mixture to lean it...it should be set lean enough to prevent fouling. I will agree leaning is a good idea on a cold engine, above idle, to get it up to operating temps. And that includes the taxi out for take-off because the Moose won't taxi at idle...hah! My IO-520D never, I mean NEVER, fouls plugs and I've spent a lot of time keeping it tuned properly. I've found an engine that routinely fouls plugs has other issues that need investigation and compensating by agressive leaning is putting a bandaid on a cancer patient. I don't teach engine maintenance...I perform it...every day.
   To pass along some things I've learned I'll submit the following....the engine NEEDS an engine monitor...I think that one piece of electronics is essential to engine health. I put an index under the instrument to show the pilot what mag fires what plug (makes troubleshooting simple). Teach the pilot how to use the darn thing (now THAT you can help with) Vernier mixture...nuff said! Digital tach...awesome. Keep the engine CLEAN! Keep the air filter CLEAN! Avoid ground ops with alt air or carb heat (DUH!) Pressure test the induction and exhaust system every 100 hours or annual. Replace old plug wires and old plugs. Clean the injectors every 100 hours or annual (I DO like the GAMI's). Check the float level in the carb and make sure the primer isn't leaking....
   While I'm sure your seminars are informative and worth every penny I'll invite you out to my shop and teach you routine engine maintenance for free....just so YOU won't be left behind ;^)

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Re: Re: Ground leaning

While this thread has been going on, I have had my annual done on my 182E. I have been aggressively leaning for my ground operations, as I have described in this thread. With many things being said in this post, I got to wondering about my idle-rich mixture. After we put the plane back together, I asked my mechanic to look at the mixture rise at idle cutoff. With the throttle closed the rpm is 550. Then when the mixture is brought back to cutoff the rpm rose to 675-700 rpm. The tech then adjusted the mixture to get only a 50 rpm rise at cutoff. Maybe this will improve the ground operations to a point of not having plug fouling while warming up and taxiing. I still plan to lean for ground ops, though.
Glenn

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Re: Re: Ground leaning

Gregg:

WOW, an excellent set of maintenance recommendations which parallels our recommendaitons exactly (I'm an A&P also).  If all owners/pilots would copy that last message and do as you are recommending, we'd have a LOT safer fleet.  NO doubt about it.  Maintenance bills would be lower, too.

You also have something else right, the PILOT's ability to understand his engine monitor and use it for proper trouble shooting is waaaay behind the power curve. We spend a LOT of time teaching these things.

I sorta-agree on the idle mixture issue... it's just that the idle mixture should be set as you describe for ISA sea level.  What about in the summer?  Do you reset it summer and winter?  What about high altitude airports?  Do you reset it when you go somewhere else?  Of course not.  It has been my extensive experience that while what you say is technically correct (that we shouldn't have to ground lean) we find it is VERY beneficial to do so for many other reasons.  You are right in that if you must lean to get the engine to run right, something is wrong.  That is not what I'm advocating. 

Also, we really should get together.  Anyone as knowledgeable as you and who recommends engine monitors would really find agresively leaned mag checks and in-flight mag checks very interesting and educational.  I have no doubt that WE could teach EACH OTHER some stuff.

Where is your shop?

Walter Atkinson
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Re: Re: Ground leaning

A 50 rpm rise might be considered a tad on the rich side.   OTOH, those who set it below a 25 rise often find it tough to start and keep running at high altitude airports.

In any case, it's one heck of a lot better than it was. <g>

Walter Atkinson
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Re: Re: Ground leaning

Shop is in Tucson (KRYN) Ryan Airfield. And I do set the mixtures for Summer and Winter ops. Since our Summer DA's are typically over 5000' I've found little problem keeping them adjusted for our conditions. Adjusting for ISA Sea Level in the Arizona Summer would be a challenge :^)
This whole thread got skewed. I agree ground leaning is a good idea at anything above idle. Using the mixture at 600-800 RPM is'nt. I do leaned mag checks...take the engine to @ 2000 RPM, lean to peak for 20-30 seconds, leave the mixture where it is and reduce to 1800 for the checks (except on the Franklin 6A-350-C1R) Mag checks in flight....might be good for some...not me. I'm usually down around <100' AGL and shutting a mag off takes my eyes off other things...hehehe.
I install the EDM-700 in every customer plane I care for. It sells itself so my job is easy...I just install it and watch them geegosh after the first flight. Funny how that one instrument keeps their minds sharp on how every cylinder, every plug is performing. Teaching them to use it is the real trick...but once they learn and apply the basics I see a marked improvement in the oil color and plug condition.
RPM rise at shutdown is baselined down around 20-50 RPM but I also fly the plane and see how it accelerates from idle to full power (go around)....if it really stumbles I'll adjust it to where a smooth application of throttle results in a smooth increase in RPM....nuff said. Come on out to Tucson...but wait till Winter or you will regret the visit ;^)

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Re: Re: Ground leaning

I enjoyed this thread.  For a while.  But I lost interest when Mr. Atkinson dishonestly accused Mr. Horn of calling pilots here too  "stupid".  Mr. Horn never said that and he's never made me feel that way.  Only Mr. Atkinson implied that he did by putting his own sentence in quotation marks to make it appear that he was quoting Mr. Horn.  It was a telling moment as to what lengths Mr. Atkinson would go to sell his product.  No thanks. 
 
  As for plug fouling, I've flown professionally for 22 years, and I've never performed "ground leaning" and I've never experienced a fouled plug from not leaning an otherwise healthy engine.  Mr. Horrell and Mr. Horn are both correct.  A healthy well-adjusted engine doesn't foul plugs and doesn't need "ground leaning".   Atkinson should go sell pink-elephant guns.  He could prove their effectiveness by pointing out the lack of pink-elephants in the area.

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Re: Re: Ground leaning

Gregg:

Seems like we agree on a lot more than we disagree on.  I'll stop in Tuscon one of these days.  You do have an unusual situation compared to most with the radical change in summer and winter temps and DA.  As much as I travel, I'd find it irritating to be constantly altering the idle mixture.  I set it for ISA, and adjust at high temps and altitudes.  It works best over the wide range of places I regularly visit and that's what I think the OEMs had in mind.

You can always lean it a tad, but it's damned hard to richen it up to keep it running when you're already full rich. <g>

You're right, these threads do get twisted around some and I HATE trying to communicate details over a keyboard.  It's fraught with difficulty.

In the end, we agree to a very large degree and that makes me feel better--two A&Ps oughta have very few minor misalignments and NO major ones, wouldn't you agree?

I need to show you these in-flight mag checks.  They are great for trouble-shooting.  I do one on every flight right before beginning the descent.  That way early problems are identified and can be addressed before the next flight.  No delays at the run-up area. <g>  I recently found a plug that was misfiring on the LOP in-flight mag check on a friend's 206 yet it passed the rich mag check.  On inspection it had a small crack in the ceramic and was arcing and about to fail completely.  Saved me time and money.  Taxied up to the shop and said, "Please change the top plug on the #4 cylinder."  The mechanic said, "You've been watching that damned JPI again, haven't you?"

Yep.  Saved hours of trouble shooting because the plug showed good on a rich run-up and on the bomb test.  I've kept that plug to use as a demo.  It's impressive to see it fail on the high-stress test, but pass everything else.  Good plugs don't do that.

Walter Atkinson
Advanced Pilot Seminars

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Re: Re: Ground leaning

Mr. Tacket:

WOW!!!

<<But I lost interest when Mr. Atkinson dishonestly accused Mr. Horn of calling pilots here too  "stupid".  Mr. Horn never said that and he's never made me feel that way.  Only Mr. Atkinson implied that he did by putting his own sentence in quotation marks to make it appear that he was quoting Mr. Horn.>>

I think you may have misread this.

Here are the quotes:

From Mr. Horn:
<<Since cruder fuel delivery and cruder instrumentation is what most of these simple, carburetor-engined airplanes consist of, it seems irresponsible to me to  recommend such advanced operating techniques categorically to everyone who flys. >>

From me:
It is important to have proper instrumentation.  It is not my position that "all of the pilots we're talking to on this forum are too stupid to do this for themselves and they should not be informed of what is possible because they might hurt themselves."  On the contrary, I think pilots are smart folks.
 
*********

I said it was not MY position...  I did not say it was HIS position. If you feel the above exchange called anyone a liar, I'm missing something and I appologize to you, PERSONALLY.  I read his post as saying that there are people here who shouldn't hear of advanced techniques. I disagree with that.

My position is that the people here are smart enough to decide for themselves once they look at the data.  I certainly did not intend to call anyone a liar and I don't think I did.  I just tried to compliment the people on this forum.

As I said, you must have misread the post.  At the least, you misunderstood my position.  I certainly didn't intend to upset you so badly.

If you had read on, I had asked George to call me.  So far, I haven't heard from him.  Hope I do.

BTW, I don't sell pink elephant guns. <G>  My dog keeps the pink elephants away. Shes' good at it.  Haven't seen one since my sophomore year of college. <VBG>  Heck after this thread I might drink enough to see another one.

We're only talking about ground leaning fercryinoutloud.  What happens around here when a SERIOUS topic gets started?

Walter

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Re: Re: Ground leaning

You did fine - Walter. I think aviation professionals are proud of their profession and sometimes Ego's get a bit stepped on. (that goes for all of us) Can you imagine if this was a topic on the proper methods of doing a "Heart Transplant" by a bunch of Cessna flyin' Doctors??  That would really be scarey.. Enjoyed your points - as well as Mr.Horn's..   How about starting a new subject.  You pick!

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Re: Re: Ground leaning

Seriously, what is a serious topic?

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Re: Re: Ground leaning

Aluminum Corrosion inside the fuselage or wings is a serious topic.

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