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Proper Leaning Technique

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dahugo

Member
We have about 60 hours on our 9A which has a brand new (well, 60 hours) IO-360. As we have a Dynon FlightDEK 180 with full engine monitors, we can safely run lean of peak, and of course we try to do so based on the "leading" cylinder.

There is a "guy" at our airport who tends to know lots of stuff, and he said leaning for LOP operation is easy--once in level flight just turn a full turn out, wait a few seconds, monitor the EGT's and CHT's, watch for LOP operation on the engine monitor, get to the back side of the curve and when you turn the knob and experiencerough operation, enrichen to smooth running. This process generally comports with running 50 degrees LOP on the leading cylinder, so its a good rule of thumb that we tend to follow.

As for descent, I generally run LOP until the last 3 or 4 minutes of flight when I just enrichen all the way for the approach. I do lean pretty aggresively on idle and during taxi.

These things have started bothering me, though, since I read an article this month in Aviation Consumer Magazine about spark plugs. While extolling the virtues of the more expensive thin wire plugs, the article quotes some engine shops which state that one of the best ways to promote detonation, and thus cause undue wear on an engine, is to lean slowly (like I do) or to just fully enrichen on descent (which I do.)

I don't want my $23,000 engine to weare unnecessarily, and everything that I read in Aviation Consumer I tend to believe. So, am I leaning incorrectly? In other words, how do you lean "quickly?" I can just picture leveling off at 6500 feet and yanking out the mixture knob and killing the engine.

And if I don't enrichen fully the last few minutes of flight, how am I supposed to enrichen upon descent, especially within a few minutes of landing?

dahugo
 
Eaa

There was a pretty good link on here recently to a EAA webinar on leaning. A little long in delivery but well worth the view. Look it up. Made sense to me and chatted about types of plugs, temps, fouling etc. Others talk of taking an online big $$ course. I found the EAA webinar was good enough and made sense to me. Seems those with good maintenance history follow similar protocols.

Cheers,
 
What I've taken away from a number of these types of seminars etc. is that when leaning (or enriching), one wants to stay away from the conditions between about 100 degrees rich of peak to slightly lean of peak. The reason for doing so is to avoid the conditions under which detonation is most likely. Therefore, the argument is to (relatively quickly) lean your mixture through this zone, going either way. Thus, pull the mixture to roughness (which should be lean of peak) and then enrichen slightly. Similarly, enriching the mixture should be relatively rapid through the critical zone.

My understanding is also that if you are relatively high and/or low-power (below 65% is what I've been told), then going through the critical zone is not an issue.

My two cents, and my understanding. Others with much more experience than I may chime in and tell me I'm full of it.

Greg
 
Not sure all of what you are hearing is sound advice. Leaning based on the "leading" cylinder? If that means the cylinder that's most lean, and you are are LOP on that cylinder, that leaves the other cylinders relatively more rich, hotter, and higher peak pressure and therefore closer to detonation. I would pay most attention the the cylinder at the other end of the spectrum, I.e., the "trailing" cylinder.

With respect to leaning quickly, one accepted technique is "the big pull" where you pretty much zip through all the intermediate stuff and go directly to LOP. Maybe a little scary the first time, but you can always richen up a bit if you over do it. Watch your fuel flows. For an io-360, 7-8 gph seems to be good, and at times I've gone even leaner. If you want to tinker, go up high, around 8K or better where your max power is 65% or less and lean as slowly as you like. There is no setting that will result in detonation at those power levels. Alternatively, you could pull your throttle back to lower power, but that seems to be sacreligous to the LOP brethren, who like to control power only with the mixture setting rather than the throttle (throttle wide open at all times when LOP).

Now, prepare to hear from RV10inOz who will try to shame you into attending the APS training. :)

Erich
 
Erich, your post is 99% accurate.

I am a firm believer in making sure what we see or hear is as accurate as possible, and from the few posts in this thread already, as you have pointed out quite easily, that understanding is the problem.

See the original poster knows some good stuff but is not showing the signs of true understanding, otherwise he would have worked out for himself what was BS and what was not, in fact he would not have started the post at all if he had good understanding.

So, while I take a small amount of offence at the slur I would want to shame you or somebody else into taking an APS course, I do thank you for the lead in. The point is, a little knowledge is what is shown in a thread, but a full education or at least to a significant level is far more powerful, and an't be gleaned from dozens of posts on a forum.

So yes I am seriously thinking the original poster could certainly benefit from some extra tuition. Heck we pay thousands for our planes, engines avionics, our licences, thousands more for an IR.....

.......... yet many folk want to cheapskate on engine management education. It is beyond belief! An APS course and an engine monitor will save you thousands of dollars over the life of your plane or flying career. Thousands in fuel, maintenance, unnecessary maintenance through good diagnostic skills, and maybe more importantly...save your life!

The original poster was concerned for the value of his $23,000 engine.

By the way.....John Deakin emailed me a few minutes ago and suggest I do offer the special deal he is sending to the Beech community. So take a look at this link.

http://www.vansairforce.com/community/showthread.php?p=717023#post717023
 
I agree on the value of the APS course.

Years ago I owned a Twin Cessna and was looking to reduce my operating and maintenance costs. I installed GAMI injectors and a JPI 760 EMS to supplement the stock EGT and CHT gauges but was not comfortable running LOP hearing all the horror stories about "frying" my engines.

At Oshkosh 2002, GAMI announced they were planning to offer a course that would teach the finer points of engine management so I attended the very first class presented by APS in Ada OK. the weekend of 13 Sep 2002.

Long story short was I enjoyed the APS experience and went on to run up nearly 1200 hours of trouble free LOP operation before I sold the aircraft.
 
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