Lycoming Leaning Techniques

[macdon221]

Good Day,

Ok, not to start the age old debate again, but I am interrested in hearing what the "collective" is doing out there for leaning aircraft engines. I fly an aircraft with an IO-360 A series fuel injected lycoming and curious as to the accepted real world procedure out there. I have read all of the info that Lycoming has to offer on their website. One of the aircraft that I fly recently had to replace the exhaust due to deformed baffles inside. Is leaning the cause?

Your Thoughts everyone...

Cheers


macdon221@yahoo.ca

[Bonanza Man]

First and foremost forget what you read about your engine from Lycoming. They are the last people you want to consult to run your engine properly. Go here and learn the proper way.


http://www.advancedpilot.com/

Under Tech, click Target EGT.

[bumper]

Pay a grand to have someone tell me how to lean my Lyc?? Not hardly.

I'll listen to the folks who built it and read on-line for free.

BTW on my Husky (carbureted), I lean to find which cylinder peaks first, then run 50F rich of that. At 2000 and 20", swinging an 80" MT, that results in less than 7 gph at about 105 knots with 26" tires.

I have an IO360 in my Mooney. I also run that 50 rich of peak, even though I'm aware I can run it LOP, I don't. 162 knots for 10 gph is just fine.

bumper

[crazyivan]

I'm all for entrepreneurship in the aviation industry (Orville and Wilbur, Rutan, Vans), but $1000 for a lecture on engines? Eh, no.

Anyway, I like bumper's method, but that requires an individual EGT for each cylinder. I have a Piper PA-22/20 with a carb O-320 and no EGT gauge. The Pacer manual says to lean until you lose RPM and then enrichen until you get the max RPMs back. The jury is still out for my plane, but 50 years of Pacers flying behind O-320s is enough proof for me that they are right.

The way I see it, if you like to tinker and squeeze every last joule of energy out of every last molecule of 100LL (like me 50% of the time), then keep tweaking and asking questions. If you are so busy that finding an hour per week to fly is difficult (like me the other 50% of the time), then follow the owner's manual. That will be the 99% solution and serve you well.

[n2485q]

I'll second what Scott said....check out the site....there is lots of FREE info there gathered from data that was not available when our engines were designed. there are lots of OWT out there and it is a chore to sort through them to sift out an understanding of what goes on inside our mills....advancedpilot has no vested interest in sharing their data....Lyc&Cont on the other hand may have a bit of CYA and admitting that the info they have put out for years might be wrong would open the floodgates of litigation.....to each his own...this topic is like arguing religion......and if you are into self flagulation, join Cessna Pilots Associatrion and search the forums for "LOP".....you could spend an entire weekend reading arguments for both sides of the issue..ad nauseum....including many posts from advancedpilot folks....

[Rob]

In simpler engined airplanes I use Ivans "pull it till it stumbles & touch it back in technique" I do this for two reasons.
A.) when I have done this in A/C with all the EGT/CHT goodies it typically yields bumpers temps... may not be ultra optimum, but safe and functional. and...
B.) I find it fascinating that no one trusts their fuel gauge beyond saying "ya...it might have gas", no one I know has a tach that reads within 50 RPM of what the real RPM is, oil pressure gauges are notorious for being a "in the green or not" instrument, and yet after all that, we are trusting EGT / CHT instruments down to the gnats ass ? The engine is going to stumble at a given condition every time, the instrument on the other hand could be giving you as much bogus information as the average internet wizzz kid
on the other hand I haven't ponied up the grand of "unvested interest" to find out what I've been missing on

[Bonanza Man]

The carb guys have it tough. Usually the best they can do is lean it until it's rough and add a little back. The injected guys have more options. The science has shown the worst place to run your engine is where Lyc and Continental say you should in the manual. Here's a chart that shows where to avoid operating your engine.


http://farm4.static.flickr.com/3400/3497470778_58390843a6_o.gif

[tcraft]

there are so many opinions on this topic. So I wasn't going to say anything, but looking at bonanzas graph unless I'm missing something or not looking at the graph correctly. It shows I would have to be 250° rich of peak or higher, in order to run safely,? Is that not right. According to the graph?

If I was to operate my plane that way, I would burn a whole bunch more gas, and I would definitely screw up my sparkplugs. Not to mention, I probably would not have the power to get off my runway.

I have an electronics international single probe EGT and usually dial it in to about 50° rich, the EGT is really nice, because once you figure out what temperature your engine runs at during the various times of the year at the different elevations you run at you can pretty much dial-in or out as you climb and descend and keep it perfect,

But, if you're not a gadget freak, running it rough. And then bumping in the mixture just past where it smooths out has always worked well . just remember to check it whenever you're flying conditions change,"altitude and/or temperature"

[mr scout]

Good Day,

Ok, not to start the age old debate again, but I am interrested in hearing what the "collective" is doing out there for leaning aircraft engines. I fly an aircraft with an IO-360 A series fuel injected lycoming and curious as to the accepted real world procedure out there. I have read all of the info that Lycoming has to offer on their website. One of the aircraft that I fly recently had to replace the exhaust due to deformed baffles inside. Is leaning the cause?

Your Thoughts everyone...

Cheers


macdon221@yahoo.ca

I have had many conversations with the folks at Dawley and Knisley about this very subject. I think the short version of there ideas has been its getting to hot....really...so working it hard and agressive leaning in climb seems to be the most logical culprit in Dawleys eyes.

I think that the use of egt/cht scanners has opened up pandora's box for running much higher temps. A hundred degrees can make a huge difference in the muffler.

[gbflyer]

So the chart that BM has there says wide open throttle. I am wondering what then the procedure might be without the balls to the wall. I never was in the habit of keeping it there.

gb

[Bonanza Man]

there are so many opinions on this topic. So I wasn't going to say anything, but looking at bonanzas graph unless I'm missing something or not looking at the graph correctly. It shows I would have to be 250° rich of peak or higher, in order to run safely,? Is that not right. According to the graph?

If I was to operate my plane that way, I would burn a whole bunch more gas, and I would definitely screw up my sparkplugs. Not to mention, I probably would not have the power to get off my runway.

I have an electronics international single probe EGT and usually dial it in to about 50° rich, the EGT is really nice, because once you figure out what temperature your engine runs at during the various times of the year at the different elevations you run at you can pretty much dial-in or out as you climb and descend and keep it perfect,

But, if you're not a gadget freak, running it rough. And then bumping in the mixture just past where it smooths out has always worked well . just remember to check it whenever you're flying conditions change,"altitude and/or temperature"

You are richer than 250 ROP on takeoff or you should be. For an IO-520 you are going to want to see a minimum 26-28 GPH at takeoff at sea level. Here at 3650 I normally see about 25 GPH. There 's nothing wrong with running ROP, as long as you do it correctly, other than to do it correctly you burn a lot more gas than you need to. The same applies to LOP, you ned to do it correctly. Another benefit to LOP is there is extremely little to no carbon monoxide so an exhaust leak into the cabin won't kill you. Also when LOP fuel flow is the sole determining factor for percent power making engine management easier. Remember 2 or 3 fuel flows and you can have several handy power settings ready to go.

[Bonanza Man]

So the chart that BM has there says wide open throttle. I am wondering what then the procedure might be without the balls to the wall. I never was in the habit of keeping it there.

gb

If you are running less manifold pressure then the red area gets smaller. The chart says basically the same thing. As you climb in altitude your manifold pressure goes down. The engine doesn't know how the manifold pressure went down, only that it did.

[tcraft]

totally agree. You definitely can't hurt an engine running rich, with the exception of maybe plugs. And of course I'm relating to an O235 so the amount of gallons burnt is different .
I have found from experience that being overly rich, may not hurt anything engine wise, I think it's good practice to adjust your mixture before every take off and not just assume full rich, and you're good to go. It's possible you could be throwing away many horses that you might need.
Also I would probably guess you could look at 50 airplanes of the same type , and it's possible their mixture controls can be in various locations when leaned out.

[nealkas]

...
B.) I find it fascinating that no one trusts their fuel gauge beyond saying "ya...it might have gas", no one I know has a tach that reads within 50 RPM of what the real RPM is, oil pressure gauges are notorious for being a "in the green or not" instrument, and yet after all that, we are trusting EGT / CHT instruments down to the gnats ass ?

That is an extraordinarily valid point!

While I don't have anything useful to add to the rest of the debate, trusting ANY gauge implicitly is sort of begging for a poke in the eye.

[hardrock]

I'm new to the forum but have been following it for some time. Having spent the 1K or whatever it was five years ago to attend the APS seminar I thought I'd chime in. Having spent lots replacing cylinders in a T210 over 10yr/1500hrs I went to APS looking for a better understanding of what my engine was doing and why. They put on a data driven seminar in a very effective way. Information that is decades old, reinforced by new data gathering technologies.

The graph referred to by BM is one of many used in the course. A more enlightening one graph's egt, cht, icp (internal cylinder pressure), hp, and bsfc, through a leaning cycle. They are all about avoiding operations in areas of high icp's which graph identical to cht's, ie high icp's/ high cht's. Refering to BM's graph, Bumper's 20" and 2000 rpm, 50 rop, you could opperate anywhere relative to peak and have what they term acceptable icp's/cht's. Change those setting to 30" and 2500 rpm's, 50 rop, and you have a very different story.

The engine in my Husky, given the altitudes and settings it normally operates at give a lot of latitude to operate with little wear and tear, the TSIO550 in my Columbia not so much.

In the quest to understand how to operate a high power engine, at high power, with an eye to minimal wear/ cost, the APS course is the best money I've ever spent in training.

[pacerflyer]

I have a O-320 B2A 160 hp in my 1957 PA 22/20. It was just overhauled with just about new everthing and I want to get as much life out of it as I can. The mechanic that did my rebuild told me to use the method Ivan discussed earlier. I am finding though that I lean on the ramp while I do my run up. The lead in the fuel gets built up in the plugs in the lower part of the cylinders and when I do mag checks it will run really rough. I lean till I lose rpm, then add till rpm comes back. EGT goes to around 1400. I let it sit like that for about 30 seconds and do a mag check again. While in the air, I lean the same way. I generally cruise at around 2200 rpm for about 110mph and around 6-7 gph.

[Ernie Tobin]

Your right pacerflyer. Leaning for all ground operations is a good idea to keep the plugs clean. In the air, the old method of lean to RPM loss then add some back, described by so many above works pretty darn good.

[jomac]

i find in my o-540 that it don't need or like to be wide open. short stuff, like lower loon and such, a breif 20-30
seconds or so of 27 " on the man press and 2400 on the rpm gauge, it will put up with. at these settings the big
lycoming builds heat real fast with the turbo running full tilt. never do i use these settings on the long/paved stuff. there really is no need as 60 % power will get the job done safely and with a lot less stress on the systems. as you guys have rightly said, the book will have u buying a new motor soon! they told me to fly it 23 sq, and i find this is a recipe for a lot of heat and about 5 or so knots more is all in speed. i fly slower nowadays, and spend most of my time making sure i don't cool it off too fast when descending, thanks to the edm-700. great engines when managed correctly. i've luckily been trained a lot in slow-flight and my bird and motor is quite happy at 60 and less on the speed, when in the tight stuff...