Adjusting Mixture

[Terry]

Hi All:

What is the proper procedure for the following scenario?

You leave Hays, Kansas and take off with a full rich mixture.

You climb to 10,000' and adjust mixture for the altitude.

Then you climb to the necessary altitudes for terrain.

You will be landing at Aspen, Colorado.

What do you set your mixture too? How do you set it?

In other words if you have to go miss you would not want full mixture because of the altitude.

I am thinking if you are full rich at that altitude you will not be able to develop full power for a go around.

Just curious.

I am referring to a 182.

Terry

 

[Ken Ibold]

What kind of engine monitoring equipment is installed? Single probe EGT gauge only? Full six-cylinder EGT/CHT engine monitoring?

 

[TMetzinger]

Tough question. If I had a fuel flow gauge, I would go full rich, back it off a couple of twists, and then, if I had to go around, I'd get the airplane properly pitched and climbing, and set the mixture using fuel flow according to the table that's placarded on later models for max FF vs altitude. Otherwise, you're guessing, and you have to just try to make a good guess. Too rich limits your power, too lean trashes your engine, so I'd err on the side of being too rich.

 

[Terry]

Hi all:

You got me stumped. I was just thinking of a plain old 182.

I thought there would be some "specific" setting for fuel mixture that you set to.

Shows my ignorance but also makes me very well aware that I need to "stay ahead of the airplane." I'll set it up on MS Flight simulator and see how I do.

Also next Saturday my son and I will be flying over and around Cripple Creek and I'll ask him how he does it.

This is one of the reasons I like this board. If I ask "stupid" questions I don't get blasted like on the other boards.

Terry Warner

P.S.> I finally got my little map up. I envy you pilots who have almost all the states colored. If my commercial license happens I'll get to color in some more states.

I am trying to figure out a way to tell the wife I need to fly to about 46 more states right away.

 

[wabower]

Density Altitude will be as important as actual altitude in your choices. During your flight planning, you should get a rough idea of ASE DA. During the climb, level and note power required at that DA, check mixture setting to determine SWAG setting if you need it. You may need to watch both power and mixture settings in the event of a Go-around at KASE. BTW, if you've been there you know that's not much fun.

Hi all:

You got me stumped. I was just thinking of a plain old 182.

I thought there would be some "specific" setting for fuel mixture that you set to.

Shows my ignorance but also makes me very well aware that I need to "stay ahead of the airplane." I'll set it up on MS Flight simulator and see how I do.

Also next Saturday my son and I will be flying over and around Cripple Creek and I'll ask him how he does it.

This is one of the reasons I like this board. If I ask "stupid" questions I don't get blasted like on the other boards.

Terry Warner

P.S.> I finally got my little map up. I envy you pilots who have almost all the states colored. If my commercial license happens I'll get to color in some more states.

I am trying to figure out a way to tell the wife I need to fly to about 46 more states right away.

 

[flyingcheesehead]

You got me stumped. I was just thinking of a plain old 182.

I'll assume that you mean a plain OLD 182.

The below is a GREAT start:

Density Altitude will be as important as actual altitude in your choices. During your flight planning, you should get a rough idea of ASE DA. During the climb, level and note power required at that DA, check mixture setting to determine SWAG setting if you need it. You may need to watch both power and mixture settings in the event of a Go-around at KASE. BTW, if you've been there you know that's not much fun.

I'd suggest that when you level out at that DA, go through the full leaning procedure for cruise, and then richen it up some (without fancy instrumentation - That is, a multi-cylinder engine monitor - this isn't an exact science by any means). Your 182 might be a bit different than the one I fly (1971), but I'd say that my setting for those up-high fields was about 3/4" out from the panel.

BTW, you take that mountain flying course yet? I overflew ASE on my trip, and I was weaving through the mountains at 13,000 feet. Peaks are in the high 14's. I flew over Loveland Pass, which is right at 12,000 on the ground. Make sure you know very well how both the plane and YOU perform that high as well.

 

[Tom-D]

During the down wind portion of your landing pattern, get the prop back to lowest pitch, (highest RPM) and go full throttle, set mixture to highest power setting (highest RPM) and leave it there for the landing.

 

[gprellwitz]

One thing I noted on the new G1000 Turbo 182 was that there was no placard for max performance fuel flow. I was rather surprised..

 

[KennyFlys]

One thing I noted on the new G1000 Turbo 182 was that there was no placard for max performance fuel flow. I was rather surprised..

What was on the cruise performance charts?

 

[sba55]

A few notes:

You cannot "trash" your engine at that altitude, no matter what you do with the mixture (assuming this isn't a turbo'd 182). Going full rich at that altitude is not only a complete waste of fuel, it might also kill your engine depending on how it is set up. I know it'd kill mine. In addition to all that, "shock cooling" happens when you force a large amount of really cold fuel into the cylinders, which, depending on the OAT, you will be doing by going full rich in the pattern.

Going full rich for landing is generally not an ideal practice anyways. At ASE, just don't mess with the mixture during descent and landing. There is no need to change the mixture that worked for you in cruise. If you're leaned at your cruising altitude, say 14,000' and you're rich of peak, you might be close to peak or even a little lean of peak. Again, the mixture doesn't matter in this situation because you won't harm your engine. If you feel some roughness, just enrich a tiny bit to get back to a point where the engine will run ok. You're very likely close to or at the best power setting at that point.

Don't make it too complicated. And in any case, setting some specific fuel flow in a go-around is way down my list of priorities.

My own approach to this issue goes something like this and it works at any altitude: Keep the mixture constant from cruise to landing (since I'm usually LOP, I'm not concerned about it much, even at lower altitudes, but if you're ROP and below 7000', I'd just enrich a little every 1000'), prop back to 2000 RPM, and land. If I have to go around, it's full prop and throttle, and the mixture is already set. If, after I get the airplane set up, I notice that I need more power, I might go ROP, but that's certainly not on my mind for the first few moments.

-Felix

 

[jesse]

Don't make this more complicated then it has to be. I'd likely set the mixture somewhere entering the pattern as Tom describes and then I'd let it be.

 

[Henning]

Hi All:

What is the proper procedure for the following scenario?

You leave Hays, Kansas and take off with a full rich mixture.

You climb to 10,000' and adjust mixture for the altitude.

Then you climb to the necessary altitudes for terrain.

You will be landing at Aspen, Colorado.

What do you set your mixture too? How do you set it?

In other words if you have to go miss you would not want full mixture because of the altitude.

I am thinking if you are full rich at that altitude you will not be able to develop full power for a go around.

Just curious.

I am referring to a 182.

Terry

Old 182 with O-470 or new with IO-540?

Either way, why would you wait to 10,000' to lean? You're not turboed are you? I start leaning with the first power reduction be it me or altitude reducing the power.

 

[bobmrg]

A few notes:

You cannot "trash" your engine at that altitude, no matter what you do with the mixture (assuming this isn't a turbo'd 182). Going full rich at that altitude is not only a complete waste of fuel, it might also kill your engine depending on how it is set up. I know it'd kill mine. In addition to all that, "shock cooling" happens when you force a large amount of really cold fuel into the cylinders, which, depending on the OAT, you will be doing by going full rich in the pattern.

Going full rich for landing is generally not an ideal practice anyways. At ASE, just don't mess with the mixture during descent and landing. There is no need to change the mixture that worked for you in cruise. If you're leaned at your cruising altitude, say 14,000' and you're rich of peak, you might be close to peak or even a little lean of peak. Again, the mixture doesn't matter in this situation because you won't harm your engine. If you feel some roughness, just enrich a tiny bit to get back to a point where the engine will run ok. You're very likely close to or at the best power setting at that point.

Don't make it too complicated. And in any case, setting some specific fuel flow in a go-around is way down my list of priorities.

My own approach to this issue goes something like this and it works at any altitude: Keep the mixture constant from cruise to landing (since I'm usually LOP, I'm not concerned about it much, even at lower altitudes, but if you're ROP and below 7000', I'd just enrich a little every 1000'), prop back to 2000 RPM, and land. If I have to go around, it's full prop and throttle, and the mixture is already set. If, after I get the airplane set up, I notice that I need more power, I might go ROP, but that's certainly not on my mind for the first few moments.

-Felix

Your approach is the same as mine...but on another board Ron Levy took me to task about it. The Lycoming Flyer does say (in it's summary on leaning) : "Some leaning on descent to traffic pattern altitude may be in order to prevent roughness or sudden engine cooling." I've never experienced roughness on descent (that I didn't cause myself by letting nature take its course) in either carbureted or injected engines. But Ron even cited some service bulletins, so I guess he must have a point.

Bob Gardner

 

[sba55]

Your approach is the same as mine...but on another board Ron Levy took me to task about it. The Lycoming Flyer does say (in it's summary on leaning) : "Some leaning on descent to traffic pattern altitude may be in order to prevent roughness or sudden engine cooling." I've never experienced roughness on descent (that I didn't cause myself by letting nature take its course) in either carbureted or injected engines. But Ron even cited some service bulletins, so I guess he must have a point.

Bob Gardner

Well, I can't say that I'm surprised. If there's one thing I learned, it's that Lyc's opinions on how to run their engines are usually wrong.

That aside, there's obviously no risk of "sudden engine cooling" if one doesn't lean (unless they mean to imply that the engine will stop and thus suddenly cool ). They're right that you might have to lean a little to prevent roughness if you're descending from ROP and high altitude and your engine won't run well LOP.

-Felix

 

[murphey]

Terry:

Even with a 182, if you're not familiar with mountain flying, stop off in the Front Range area (Denver, Ft Collins, Greeley, etc) and spend a couple hours on the ground with an instructor fluent in mountain flying. Then spend another couple hours in the air with the instructor. Until you have experimented with your aircraft (over flat land, not mountains!) dealing with altitudes, don't go to Aspen.

And don't even think about going full rich. You'll flood the engine.

Remember the POH is written for a brand new engine, a brand new aircraft, at sea level, with a test pilot in the aircraft and a lawyer on the ground.

 

[poadeleted20]

Tom Downey's advice is the most technically correct. However, going to full throttle on downwind is often impractical. The best answer is to know just about where your mixture will be when you set it for takeoff at that elevation, and that's a matter of experience. You would do as discussed - leave the mixture where it was in cruise at least until turning final and preferably applying power for go-around, and then advance it to the max-power position for that elevation. In a fuel-injected plane with a calibrated fuel flow gauge, that's easy -- just push it until the needle is pointing at the altitude. Otherwise, it's a matter of experience and guesswork. Err on the side of richness, and then fine-tune for max power once the houses are getting smaller.

 

[SkyHog]

Here's how I do (did, when I still flew) it:

Remember, there are no low DA takeoffs in New Mexico

Absent fancy gauges, when you takeoff, you lean to max RPM. The airplane doesn't care where the ground is, just what altitude its at. If you're flying from Hays to Leadville, at some point along the way, you're going to have to cross the airport elevation. Lean for max RPM at that altitude, and take note of where you set it.

When you come in, set the mixture back to that spot, and you'll be pretty damn close to perfectly leaned for max performance.

 

[Henning]

Tom Downey's advice is the most technically correct. However, going to full throttle on downwind is often impractical. The best answer is to know just about where your mixture will be when you set it for takeoff at that elevation, and that's a matter of experience. You would do as discussed - leave the mixture where it was in cruise at least until turning final and preferably applying power for go-around, and then advance it to the max-power position for that elevation. In a fuel-injected plane with a calibrated fuel flow gauge, that's easy -- just push it until the needle is pointing at the altitude. Otherwise, it's a matter of experience and guesswork. Err on the side of richness, and then fine-tune for max power once the houses are getting smaller.

Y'all know that you can just use the EGT to find peak at a reduced power setting as well. The mixture ratio will still be indexed to the altitude regardless the power setting.

 

[Tom-D]

Y'all know that you can just use the EGT to find peak at a reduced power setting as well. The mixture ratio will still be indexed to the altitude regardless the power setting.

In lots of old 182s there are no fancy gauges, do like I have been doing nearly 50 years, it requires about 10 seconds at full throttle to get it done, and retard the throttle to glide power settings.

I'm more inclind to be looking out the window and setting power by ear than looking at gauges in the pattern.

 

[Henning]

In lots of old 182s there are no fancy gauges, do like I have been doing nearly 50 years, it requires about 10 seconds at full throttle to get it done, and retard the throttle to glide power settings.

I'm more inclind to be looking out the window and setting power by ear than looking at gauges in the pattern.

As far as that goes, I can get it close enough by ear on descent and give it a final trim if I have to go around. If I have to fly a downwind, I can trim the mix there.

 

[poadeleted20]

Y'all know that you can just use the EGT to find peak at a reduced power setting as well. The mixture ratio will still be indexed to the altitude regardless the power setting.

It's a bit harder to find peak power (about 75F +/-25 rich of peak EGT) than peak EGT using the EGT gauge. For FP props, it's a lot easier to use the tach -- just lean to peak RPM and you're done.

 

[Henning]

It's a bit harder to find peak power (about 75F +/-25 rich of peak EGT) than peak EGT using the EGT gauge. For FP props, it's a lot easier to use the tach -- just lean to peak RPM and you're done.

That is a bit more difficult at reduced power, and pretty much impossible with a CS prop.

 

[poadeleted20]

That is a bit more difficult at reduced power

Since the mixture setting at reduced power is well off what it needs to be for peak power at full throttle, that's not relevant, although I don't think it's much more difficult to look for peak RPM at one throttle setting than another.

 

[flyingcheesehead]

Here's how I do (did, when I still flew) it:

Remember, there are no low DA takeoffs in New Mexico

Absent fancy gauges, when you takeoff, you lean to max RPM. The airplane doesn't care where the ground is, just what altitude its at. If you're flying from Hays to Leadville, at some point along the way, you're going to have to cross the airport elevation. Lean for max RPM at that altitude, and take note of where you set it.

When you come in, set the mixture back to that spot, and you'll be pretty damn close to perfectly leaned for max performance.

Nick,

That works great... On a fixed pitch prop.

 

[flyingcheesehead]

One thing I noted on the new G1000 Turbo 182 was that there was no placard for max performance fuel flow. I was rather surprised..

Huh? I have never seen an airplane that had max performance fuel flow on a placard.

 

[SkyHog]

Nick,

That works great... On a fixed pitch prop.

Should work with a variable too, lean properly at the airport elevation's altitude, and blammo, you're leaned properly for max performance should you have to go around later.

 

[poadeleted20]

Huh? I have never seen an airplane that had max performance fuel flow on a placard.

I've seen it in several. Also as markings on the fuel flow gauge.

 

[flyingcheesehead]

Should work with a variable too, lean properly at the airport elevation's altitude, and blammo, you're leaned properly for max performance should you have to go around later.

But if your engine is making enough power to get the prop off the low-pitch stop, the RPM will remain the same, so you can't lean to peak RPM.

 

[flyingcheesehead]

I've seen it in several. Also as markings on the fuel flow gauge.

IIRC the Arrow had % power markings on the fuel flow gauge, and I'm sure there are planes out there that have it on a placard, but I was mostly expressing my surprise that Grant has apparently flown enough planes with it on a placard, that he was surprised it *wasn't* on a placard.

Maybe A&M adds such things?

 

[Tom-D]

Since the mixture setting at reduced power is well off what it needs to be for peak power at full throttle, that's not relevant, although I don't think it's much more difficult to look for peak RPM at one throttle setting than another.

All you really need to know is, you have the right mixture for the go around.

 

[gprellwitz]

Huh? I have never seen an airplane that had max performance fuel flow on a placard.

Check out this picture of a 1999 182S behind the control lock (left picture). That's why I expected to see it on the T182T I was flying.
Though, since it isn't on this 2002 T182T, I guess I shouldn't be surprised.

 

[sba55]

Also, keep in mind that those charts or placards quite often show fuel flows that are too low, maybe significantly so. If you're going to use them as a reference, I'd make sure that they place you at least 150 degrees rich if you're operating anywhere near sea level and are concerned about setting the mixture properly for a possible go-around....you might only be 50 degreed rich, and that + full power will significantly shorten the life of your engine.

Better yet, if it's your plane, get at least a simple CHT/EGT monitor. Used ones are quite cheap, and will, within two or three years, pay for themselves. A friend of mine, who's flying a Bonanza, relied (somewhat) on the factory CHT gauge before he bought an engine monitor. It was reading about 40 degrees low, and his engine life was half of what it is now....

-Felix

 

[Terry]

Hi All:

Thought you might enjoy some photos of my Colorado trip.

We were at 11,500 for most of the shots. We came around the north side of the peak and then over by the Royal Gorge. Weather was beautiful and very smooth.

Terry

 

[coach]

Hi All:
What is the proper procedure for the following scenario?
You leave Hays, Kansas and take off with a full rich mixture.
You climb to 10,000' and adjust mixture for the altitude.
Then you climb to the necessary altitudes for terrain.
You will be landing at Aspen, Colorado.
What do you set your mixture too? How do you set it?
In other words if you have to go miss you would not want full mixture because of the altitude.
I am thinking if you are full rich at that altitude you will not be able to develop full power for a go around.
Just curious.
I am referring to a 182.
Terry

I fly an 182 with a home base of 6300', all I can tell you is what works for me. Often you land in the afternoon when the density altitude is 1 to 3 thousand feet higher. If you are leaned well at 10 thousand feet I would give it only a couple of twists rich. If you are full rich and have to do a go around you are asking for trouble. Be careful with carb heat, it can really change the mixture at altitude, and often with the low humidity in the mountains it is not necessary . (did I just say that?) When I put the new motor in the plane it became very difficult to lean the new carburetor precisely by ear, using the EGT is invaluable. The only down side of relying on the EGT is I have been getting mixed information on the best temperature. The mechanic tells me one thing and other pilots with 182's tell me others. The numbers vary from 1350 to 1450? Best wishes.

 

[Henning]

I fly an 182 with a home base of 6300', all I can tell you is what works for me. Often you land in the afternoon when the density altitude is 1 to 3 thousand feet higher. If you are leaned well at 10 thousand feet I would give it only a couple of twists rich. If you are full rich and have to do a go around you are asking for trouble. Be careful with carb heat, it can really change the mixture at altitude, and often with the low humidity in the mountains it is not necessary . (did I just say that?) When I put the new motor in the plane it became very difficult to lean the new carburetor precisely by ear, using the EGT is invaluable. The only down side of relying on the EGT is I have been getting mixed information on the best temperature. The mechanic tells me one thing and other pilots with 182's tell me others. The numbers vary from 1350 to 1450? Best wishes.

Actual temperature outside of max temp is irrelevant and constantly changing depending on how much power you're making. What you are looking for is peak, regardless of the number, and where you are leaning in regards to peak.

 

[poadeleted20]

One thing's for sure -- you can make leaning a lot more complicated than it has to be.

 

[TMetzinger]

Check out this picture of a 1999 182S behind the control lock (left picture). That's why I expected to see it on the T182T I was flying.
Though, since it isn't on this 2002 T182T, I guess I shouldn't be surprised.

If it's turbonormalized, you're essentially at sea level up to the turbo's critical altitude, so a placard may not be required. I've seen the placard on normally aspirated C182s and 206s.

 

[Terry]

My Pictures! My Pictures!

No one noticed I adjusted the mixture correctly and had a great flight and took pictures for everyone.

Terry

 

[gismo]

Actual temperature outside of max temp is irrelevant and constantly changing depending on how much power you're making. What you are looking for is peak, regardless of the number, and where you are leaning in regards to peak.

I'm not sure what you meant by that Henning, but the APS folks recommend adjusting the mixture at full power during the initial takeoff roll to achieve the same EGT you normally see at full power, full rich mixture at a relatively low DA. The range they recommend for that is 1250-1350F.

 

[sba55]

I'm not sure what you meant by that Henning, but the APS folks recommend adjusting the mixture at full power during the initial takeoff roll to achieve the same EGT you normally see at full power, full rich mixture at a relatively low DA. The range they recommend for that is 1250-1350F.

That's odd. I'm pretty sure that absolute EGT temps are not relevant to leaning (as long as one doesn't exceed engine/turbo specs, of course). I think that Henning was just pointing out that the ideal EGT for takeoff for a given plane will depend on that plane's setup, and setting one number for carb'ed 182 is not helpful.

I suspect that most engines will produce EGTs in the range you mentioned if sufficiently rich, though. With my IO520, I want to be 200dfROP on takeoff, which translates to 1250 or so.

-Felix