Leaning the mixture???

[Pilot124]

I have been taught one way to lean (#1) but been recently told that it is not correct. That (#2) is the right way to lean. I want to pass the right procedure to my students without any confussion. What were you taught and what do you use????????? Thanks 124

1. Lean for RPM drop then enrichen

2. Lean to peak (slight rise) Then enrichen slightly


Assuming no EGT guage...................................................................................

 

[minitour]

hmm...I always listened and watched while I leaned.

Lean until the RPM maxes out (right before the pbbbbbb sound that makes first time pax go "wtf?"). I'm usually pretty good with fuel burn calculations, so I can't be too far off....on the other hand, I could be the luckiest bastage on Earth too...

-mini

....man...that didn't help at all...sorry

 

[SSDD]

Its been a while, but if I remember correctly, Continental and Lycoming had different procedures for leaning. My advise is to follow the manufacturer's recommendations.

 

[USMCmech]

1. Lean for RPM drop then enrichen

2. Lean to peak (slight rise) Then enrichen slightly

Both #1 and #2 are the same thing.

As you pass peak EGT, the power drops off dramaticly. There is not enough gas for the amount of air. This causes the RPM drop.

Stay about 50 deg from peak EGT on either side (lean or rich) this will keep the chance of detonation down.

 

[midlifeflyer]

How do you know where the peak is until you see the drop?

If you lean with an EGT, you will see the temperature rise as the rpm rises and then the temperature drop as you go past peak and the rpm drops. Although the EGT is more accurate, the idea in either case is the same: find the leanest point at which the airplane will operate.

But if you look at the POH it will usually recommend something like 50 degrees rich of peak. So, how do you approximate that without an EGT? You find the peak and enrichen slightly for engine cooling.

I really don't think #1 and #2 are saying anything different. Both result in an approximation. Maybe it's just two different people saying the same thing in different ways, each convinced that his is the only right one.

"It's a dozen donuts!"
"No! You're absolutely wrong, It's =twelve= donuts!"

 

[Pilot124]

I think you are right midlife....Same thing said 2 different ways. Thanks

 

[Vector4fun]

But if you look at the POH it will usually recommend something like 50 degrees rich of peak. So, how do you approximate that without an EGT? You find the peak and enrichen slightly for engine cooling.

I know a lot of POHs say something similar to that, but all the stuff I've read recently on AvWeb, Cessna Pilot's association, etc. say that's not a good practice. They say if you're going to run ROP, then run at least 100 deg. ROP. Supposedly, 50 deg ROP is about the worst condition for the exhaust valves and for heat/pressures.

That said, without an EGT, I just lean till it stumbles a bit, and then push it back in about 1/4". Can't say that it make a lot of difference on a low-powered, carburated engine.

 

[GravityHater]

It all depends on the ambient conditions, phase of flight, instrumentation, and engine.