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View Poll Results: When do you Lean?
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I start thinking about leaning before I leave the house
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94 |
62.25% |
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I lean above 3K feet or in a cruise altitude
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53 |
35.10% |
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I only lean above 3K feet
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4 |
2.65% |
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I'm rich in every sense of the word, I never lean!
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0 |
0% |

10-08-2012, 08:01 PM
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Join Date: Jul 2011
Location: Dallas, TX
Posts: 321
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Engine Leaning - Service Instruction 1497A
Found video on Letters from flyover Country:
I was also taught this wrong. Read it all but pay special attention to page 2 section B #2. I was always taught don't lean below 3K. This says if you're flying in cruise at 1000 then lean it to max RPM no exceptions.
http://www.lycoming.com/support/publ...fs/SI1497A.pdf
This instruction sheet and the video below was commissioned by Emery Riddle from Lycoming and Cessna on why their engines were giving them so much headache in the training environment. Worth a look.
http://www.eaavideo.org/video.aspx?v=1678859198001
Now how many of you were taught to NOT lean below 3000?
__________________
Bob
RV-10 QB Here 8-25-19
RV-7
My brain shows a remarkable capacity to not willingly accept information that it considered useless.
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10-08-2012, 09:05 PM
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Join Date: Dec 2009
Location: Boulder, CO
Posts: 4,435
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My experience may be an outlier. I've found that it's nearly always possible to lean effectively, even at sea level.
I suspect that carburetors (all my experience leaning is with carbs) have sufficient rich margin to handle cold weather at sea level. That means that there's room to lean for standard day conditions.
But I recognize that this might apply to my engine and airframe alone, and caveat, it's not an RV.
Dave
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10-08-2012, 10:18 PM
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Join Date: May 2008
Location: Brisbane Qld. Aust.
Posts: 2,271
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Yet another poorly written document from Lycoming.
In an attempt to create a one size fits all "cookbook" they have once again failed.
Interesting to not however they have finally addressed the issues of agressive leaning on the ground. About time!
Quote:
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This says if you're flying in cruise at 1000 then lean it to max RPM no exceptions.
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No that is not what it says however what it does say is a bit of a shambles.
It talks about <3000' to leave it full rich, well I would counter that with why cruise below 3000 at full rich when a proper assesment of the power setting required would determine what is appropriate, but at 1000' and full bore, I use about 80LOP, and this is the most appropriate, unless I want the extra 4 knots, in which case 200-250ROP ( Full Rich) is the go but geez the fuel burn is horrendous.
Now what REALLY concerns me is this garbage.
Quote:
2. Cruise
Make the fuel mixture Lean to maximum RPM (all altitudes). Leaning Technique
a. Slowly make the fuel mixture Lean until the RPM decreases.
b. Make the fuel mixture Rich until the engine operates smoothly.
c. Make the fuel mixture Rich by turning the mixture knob an additional 1/2 turn (approximately 180 degrees rotation).
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So lets do that mental flight again....remember all altitudes. Now assuming the engine is not like mine, and many VAF'ers who have tuned their injectors, the point at which the roughness goes away may well be 60-80F LOP, however a factory C172 with a stock Lycoming may not be that good, most likley not, so where do you think this bit of leaning advice is going to get you? Maybe 20F LOP, 50F ROP? Who knows?????
Now of course the average C172 student may well pull the throttle back to 2300 RPM and in doing so the MP and RPM are such that the max possible power is around 65-70% anyway, but it does not specify anything, so full bore down the beach at 500' is possible!

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David Brown
DYNON Authorised Dealer and Installer
The two best investments you can make, by any financial test, an EMS and APS!
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10-08-2012, 10:19 PM
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Join Date: May 2008
Location: Brisbane Qld. Aust.
Posts: 2,271
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__________________
______________________________
David Brown
DYNON Authorised Dealer and Installer
The two best investments you can make, by any financial test, an EMS and APS!
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10-09-2012, 01:09 AM
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Join Date: Jan 2005
Location: NC25
Posts: 3,507
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Quote:
Originally Posted by David Paule
My experience may be an outlier. I've found that it's nearly always possible to lean effectively, even at sea level.
I suspect that carburetors (all my experience leaning is with carbs) have sufficient rich margin to handle cold weather at sea level. That means that there's room to lean for standard day conditions.
But I recognize that this might apply to my engine and airframe alone, and caveat, it's not an RV.
Dave
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I lean all the time at all altitudes including on the ground and my RV has been flying healthy for the last 15-years and over 2,600 hours. I got 2,200 hours on the first set of cylinders and if I had not leaned aggressively all the time, I would never had made it.
On climb out, I do watch EGT to make sure that it stays on the rich side of peak.
Total engine hours are over 5,500 hours.
__________________
Gary A. Sobek
NC25 RV-6 Flying
3,400+ hours
Where is N157GS
Building RV-8 S/N: 80012
To most people, the sky is the limit.
To those who love aviation, the sky is home.
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10-09-2012, 04:31 AM
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Join Date: Feb 2005
Location: Huskerland, USA
Posts: 5,862
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Quote:
Originally Posted by RV6_flyer
I lean all the time at all altitudes including on the ground and my RV has been flying healthy for the last 15-years and over 2,600 hours. I got 2,200 hours on the first set of cylinders and if I had not leaned aggressively all the time, I would never had made it.
On climb out, I do watch EGT to make sure that it stays on the rich side of peak.
Total engine hours are over 5,500 hours.
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Now that is a testimonial. Well done. 
__________________
RV-7 : In the hangar
RV-10 : In the hangar
RV-12 : Built and sold
RV-44 : 4 place helicopter on order.
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10-09-2012, 05:11 AM
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Join Date: Apr 2009
Location: USA
Posts: 1,499
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Easier to say when I don't lean...
Near SL start up and takeoff to 1000' agl. Any other time I am leaning.
I have stock IO-540. Max LOP with massive electrode plugs was 30F. Now with fine wire plugs on the bottom I am getting 40F before it gets rough. I still need to balance injectors but 10.3 gph is much better than 13.5 gph.
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Good judgment comes from experience, and a lot of that comes from bad judgment.
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10-09-2012, 05:21 AM
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Join Date: May 2008
Location: Brisbane Qld. Aust.
Posts: 2,271
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Wayne,
Just remember at lower powers, in the 8-12,000 feet range around 10-20F LOP is where you are efficient, otherwise speed loss starts hurting you.
Down low you will probably get 80F LOP at say WOT, 2400 and at 1000', give it a try, you might be surprised how the relationships work, 
__________________
______________________________
David Brown
DYNON Authorised Dealer and Installer
The two best investments you can make, by any financial test, an EMS and APS!
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10-09-2012, 06:11 AM
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Join Date: Mar 2011
Location: Tulsa, Ok
Posts: 98
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Leaning
I think "Garbage" is pretty over the top. We fly aerial detection at 2500 'if we're lucky, sometimes 1500'. I teach the commercial pilots to pull the mixture back as soon as the oil pressure comes up, and aggressively lean when we're level. We get 3000 hours out of our 320 E2d's. Promise, not going to change.
Don
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10-09-2012, 07:01 AM
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Join Date: Jan 2005
Location: St. Paul, MN.
Posts: 4,792
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Quote:
Originally Posted by Subwaybob
Now how many of you were taught to NOT lean below 3000?
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Yep, and it makes sense why we were taught that. As Mike Busch said, the CFI didn't want to give us too much to think about.
I've been working very hard to get into the leaning game the last few months and I loved the video. As I mentioned on my night flight the other night, I was at 3,000 MSL and could easily lean it out to 5.6-6 GPH (IO-360) which would be about 90-100 LOP and I'm still motoring along at 140 knots. But I'm just not sure how lean is too lean. Mike says just above engine roughness. Dare I? Just not sure. More experimenting needed. And haven't flown enough long cross country -- yet -- to do a lot of experimenting.
However, as I might've indicated on the original LFFC post (I can't recall, I might've only mentioned it on Facebook), I'm confused about WOT and leaning.
Busch said the ONLY time he pulls the throttle back is on landing; that he uses mixture to set power from takeoff all the way down. I'm just a fixed pitch grunt, and I'm not at all sure how that would work.
Also, I thought it was really interesting that he does not go full rich on landing. That, he says, is only in case you have to go-around and he says if you're confident enough in your ability to quickly do what you have to do in the event of a go-around, keep it lean.
I'm still thinking about whether I want to do that. 
Last edited by LettersFromFlyoverCountry : 10-09-2012 at 07:04 AM.
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