What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Contradictory advice regarding leaning on the ground

erich weaver

erich weaver

Well Known Member
I spoke with Don at Airflow Performance this morning and questioned him about the need for the commonly advised practice of leaning while on the ground. According to Don, if your AFP fuel injection system is set up properly, there is no need for leaning on the ground. To test if you have it set up right, lean at idle and if you get more than a 0.2 inch decrease in manifold pressure, your idle mixture is set too rich. The exception to his "no ground leaning" rule is if you are away from your home base and the airport where you are located is at a significantly higher elevation than home.

I brought this up in another thread awhile back, but thought it was worthy of its own thread after confirming Don's position. His advice makes sense to me, but I am unsure if applies to all fuel injection systems or not. I also did not think to ask him about the reverse situation, where your home base airport is at a high elevation and you fly to a sea level airport; there would seem to be no way to enrichen other than to remove the cowling and adjust the idle mixture screw. Perhaps in that situation, one would want to have the idle mixture set slightly rich at your home base and lean manually as necessary

I am not sure why there is this apparent contradiction to what is commonly preached by Mike Busch and other knowledgable folks. Any thoughts?

erich
 
It's not so much contradictory as it's a good advice from Don to get your fuel system tuned properly... and all Don's say is that with a properly set up system you don't have to mess with it much.

Considering that the adjustment is done at the throttle body, obviously if you're based at a high elevation you'd want it set up rich... it's not an easy adjustment you wanna make on each flight.. You can always lean it, but you can't enrich it if you're full rich on the red knob already.
 
If you lean on the ground, then lean aggressively so that you don't take off with a lean mixture. I often lean on the ground to stop the plugs fouling, by pulling the red knob until the engine nearly stops I'm sure that it won't go beyond around 1800rpm in that condition, so no-way I can take-off without going rich. Taking off half lean risks detonation :(

Pete
 
Does Don have a no ground leaning "rule"? Or is it his guidance to set it up properly to begin with? I'd like to hear of any circumstance where leaning agressively on the ground (red knob) does anything but good. Many airplanes are set up way too fat at idle, and that leads to plenty of problems.

Having said that, I'm sure he indicated the idle mixture (at the servo) should be set at sea level rather than "home base". I can see someone setting their mixture at home in Denver and then try fly into a sea level airport and go way lean in the pattern. Remember, you can always go leaner than the servo setting with the red knob, but you cant go richer.
 
The point of my original post was that while most everyone recommends leaning aggressively on the ground, Don says that this is unnecessary if your idle mixture screw is set properly (see original post regarding the exception to this). And yes, I see those two positions as contradictory. I wouldnt think the "lean on the ground" crowd would just be assuming that everyones idle mixture screw is set too rich when handing out their leaning advice.

I do understand the point made below that leaning on the ground cant hurt; worst case is the engine shuts down or no there is no power when advancing the throttle, so no harm while on the ground other than a slight delay.

Perhaps this is just a matter of a slight disagreement regarding the appropriate idle mixture screw setting, with Don advising to set it so that it is "perfect" for your home base airport, and others preferring a setting that is "a little rich of perfect" so that you will still be good for lower elevation airports and then just relying on manual leaning with the mixture knob as standard practice at the home airport to reach mixture nirvana.

erich
 
Toobuilder said:
I'm sure he indicated the idle mixture (at the servo) should be set at sea level rather than "home base". I can see someone setting their mixture at home in Denver and then try fly into a sea level airport and go way lean in the pattern. Remember, you can always go leaner than the servo setting with the red knob, but you cant go richer.
Click to expand...

Good point, but Don made no mention to me that the idle mixture screw setting had to be adjusted at sea level. I think I will send him an email to get clarification on this.

erich
 
I can see where the term "agressive leaning" could use some context. While it is true that many engines are way too fat at idle, one can still lean "aggressively" on a well tuned example. The goal of a proper idle mixture is to allow the engine to operate from through the complete range of weather conditions, altitude and possible rapid throttle movement... In other words, it has to take whatever you throw at it. Since the goal of leaning "on the ground" is only to make the engine run smoothly, there is margin to lean without any fear. The worst thing that can happen is you lean too much and the engine quits. Not a big deal on the taxiway.
 
Setting your idle mixture on Airflow FI

I can only speak for Airflow Performance Fuel Injection systems since we are the designer and manufacture of these systems. We encourage customers to set the idle mixture with the mixture control in the full rich position. Setting the idle mixture with the idle mixture adjustment to get the engine to run the smoothest and or using the MAP to indicate the correct mixture will get the engine idling at it?s most efficient fuel mixture setting. Therefore additional leaning with the manual mixture control makes the engine run with the idle mixture not at the ideal point. What people have to remember here is that there is no feedback in the idle circuit so if it changes a bit from time to time it?s not a big deal. The important thing here is that the engine takes the throttle (like in a go around situation) and the engine doesn?t quit on a deceleration. If you find the engine runs a little rough after landing on the taxi back, run the engine up a bit and clear it out. If it continues to run rough hot then you have issues with possibly boiling fuel in the nozzle lines. There are ways to address that and that will be left to our FI 101 classes, as there are too many factors that effect idle performance to be discussed here.

So don?t get to rapped around the axel with this idle mixture stuff. Set it with the engine warmed up to operating temperature, mixture full rich. Set idle to be 750 RPM and the mixture to give the smoothest idle which will be the lowest MAP. Make sure the engine takes the throttle and doesn?t want to quit on the deceleration. This isn?t like you BMW or KIA for that matter. For those of you like me, you had to mess around with the carbs back in the 60?s to get your engine to idle well; it was a ?feel? thing. Sometimes you had to be patient on cold days and on hot days the engine was a bit cantankerous to start, especially if you had a hot cam in the engine. This is the same way. Set it and go fly. If it changes a bit form day to day that?s your baby talking to you. It has personality.

Don
 
My stock Van's -D4A5 came out of the box starting and idling perfect. No adjustments were needed. After startup and landing I pull the red knob out approx 1", which is about where it is at 12,500' running LOP. I notice a drop in fuel flow which seems to be a good thing along with nice clean plugs. I do ensure it is out far enough that it stumbles if throttle is moved forward more than 1/2". I hope this is an acceptable procedure that I am doing.
 
Last edited:
erich weaver said:
I spoke with Don at Airflow Performance this morning and questioned him about the need for the commonly advised practice of leaning while on the ground. According to Don, if your AFP fuel injection system is set up properly, there is no need for leaning on the ground. To test if you have it set up right, lean at idle and if you get more than a 0.2 inch decrease in manifold pressure, your idle mixture is set too rich. The exception to his "no ground leaning" rule is if you are away from your home base and the airport where you are located is at a significantly higher elevation than home.

I brought this up in another thread awhile back, but thought it was worthy of its own thread after confirming Don's position. His advice makes sense to me, but I am unsure if applies to all fuel injection systems or not. I also did not think to ask him about the reverse situation, where your home base airport is at a high elevation and you fly to a sea level airport; there would seem to be no way to enrichen other than to remove the cowling and adjust the idle mixture screw. Perhaps in that situation, one would want to have the idle mixture set slightly rich at your home base and lean manually as necessary

I am not sure why there is this apparent contradiction to what is commonly preached by Mike Busch and other knowledgable folks. Any thoughts?

erich
Click to expand...

You can not harm an engine by leaning it on the ground. Figure out what works best for you an do it.

I lean aggressively from start to stop because it helps keep the plugs clean and it saves fuel.
(this is not expert opinion - just my opinion)
 
Don at Airflow said:
I can only speak for Airflow Performance Fuel Injection systems since we are the designer and manufacture of these systems. We encourage customers to set the idle mixture with the mixture control in the full rich position. Setting the idle mixture with the idle mixture adjustment to get the engine to run the smoothest and or using the MAP to indicate the correct mixture will get the engine idling at it?s most efficient fuel mixture setting. Therefore additional leaning with the manual mixture control makes the engine run with the idle mixture not at the ideal point. What people have to remember here is that there is no feedback in the idle circuit so if it changes a bit from time to time it?s not a big deal. The important thing here is that the engine takes the throttle (like in a go around situation) and the engine doesn?t quit on a deceleration. If you find the engine runs a little rough after landing on the taxi back, run the engine up a bit and clear it out. If it continues to run rough hot then you have issues with possibly boiling fuel in the nozzle lines. There are ways to address that and that will be left to our FI 101 classes, as there are too many factors that effect idle performance to be discussed here.

So don?t get to rapped around the axel with this idle mixture stuff. Set it with the engine warmed up to operating temperature, mixture full rich. Set idle to be 750 RPM and the mixture to give the smoothest idle which will be the lowest MAP. Make sure the engine takes the throttle and doesn?t want to quit on the deceleration. This isn?t like you BMW or KIA for that matter. For those of you like me, you had to mess around with the carbs back in the 60?s to get your engine to idle well; it was a ?feel? thing. Sometimes you had to be patient on cold days and on hot days the engine was a bit cantankerous to start, especially if you had a hot cam in the engine. This is the same way. Set it and go fly. If it changes a bit form day to day that?s your baby talking to you. It has personality.

Don
Click to expand...

Good stuff, Don, but there is no compensation for temperature change.

The difference from 30F to 104F in fuel air ratio with a mechanical setting is considerable. Probably best technique is to set idle mixture at about 60F OAT and forget about it.
 
Ron Lee said:
My goal is to reduce the chance of plug lead fouling.
Click to expand...

Exactly. My point is that even a "correct" idle mixture is fatter than needed "just" to keep the prop turning... When on the ground, we are not worried about throttle transients of any kind, so we can lean to within a hairs breadth of killing the engine without any downside.

To Don's point, this is not something to be worried about - set the mixture correctly and forget it will be just fine for the engine.

BUT! to take this a bit off topic, those of us who get in the habit of "fiddling" with the mixture on the ground do so by ear (yes, I grew up with big cams and carburetors in my cars too). And IMHO, we are more aware of altitude and temperature differences and are therefore less likely to attempt a takeoff from a high altitude airport with the mixture full rich. IIRC, that recent Stinson crash into the trees had the mixture knob full forward. I would opine that this was the result of rote process rather than reacting to conditions.

So in the end, aggressive leaning may not buy you much, but it certainly does not hurt.
 
Don at Airflow said:
I can only speak for Airflow Performance Fuel Injection systems since we are the designer and manufacture of these systems. We encourage customers to set the idle mixture with the mixture control in the full rich position. Setting the idle mixture with the idle mixture adjustment to get the engine to run the smoothest and or using the MAP to indicate the correct mixture will get the engine idling at it?s most efficient fuel mixture setting. Therefore additional leaning with the manual mixture control makes the engine run with the idle mixture not at the ideal point. What people have to remember here is that there is no feedback in the idle circuit so if it changes a bit from time to time it?s not a big deal. The important thing here is that the engine takes the throttle (like in a go around situation) and the engine doesn?t quit on a deceleration. If you find the engine runs a little rough after landing on the taxi back, run the engine up a bit and clear it out. If it continues to run rough hot then you have issues with possibly boiling fuel in the nozzle lines. There are ways to address that and that will be left to our FI 101 classes, as there are too many factors that effect idle performance to be discussed here.

So don?t get to rapped around the axel with this idle mixture stuff. Set it with the engine warmed up to operating temperature, mixture full rich. Set idle to be 750 RPM and the mixture to give the smoothest idle which will be the lowest MAP. Make sure the engine takes the throttle and doesn?t want to quit on the deceleration. This isn?t like you BMW or KIA for that matter. For those of you like me, you had to mess around with the carbs back in the 60?s to get your engine to idle well; it was a ?feel? thing. Sometimes you had to be patient on cold days and on hot days the engine was a bit cantankerous to start, especially if you had a hot cam in the engine. This is the same way. Set it and go fly. If it changes a bit form day to day that?s your baby talking to you. It has personality.

Don
Click to expand...

Don,

Does any of this get modified for those of us at high elevation home fields(5800 in my case) who fly to sea level fields?

Jim Berry
RV-10
 
So in the end, aggressive leaning may not buy you much, but it certainly does not hurt.
Click to expand...
I had always been of this view, and even felt that with a "lean" setting, the engine would warm up quicker.

But now throw another thought in the ring ;) See the thread (somewhere) about pre-heating engines and a link to how/where the real harm comes from during cold starts. It is in essence not only the different materials of the pistons and cylinders, but the rate of heating (and hence expansion) of them after start. The "light" piston heats quicker, expands, and can contact the cylinders whilst thye are still warming. Warming up "lean" would seem to only make this process worse?

I am now tending to consider warming the engine after start full rich, especially in the early stages, to slow the warm up rate. No idea if there's any truth / validity in the above, so open to thoughts?
 
Seems to me that if your fuel metering device has the capability to have the correct mixture at seal level on a very cold day, then at standard conditions, even at sea level, there's sufficient margin there to justify leaning.

If it doesn't have that capability, then how would it prevent an excessively lean mixture in very cold weather, even at full rich?

Dave
 
Idle mixture re-visit

Like I said before, there?s no feedback in the idle circuit. So the fuel flow is fixed wherever it is set. The fuel flow is the same hot, cold, high altitude or below sea level. I guess if you were being really scientific about it you would have to know the optimal fuel flow with all these parameters including the pumping change of the engine with temperature and air density. In reality we have seen that you need around a 50 degree change in temperature or a 5000 foot change in altitude to actually have to readjust the idle mixture to make the engine run adequate. So for those that have home fields above 5000 feet and then fly to sea level, you would have to set your idle mixture a bit on the rich side. Again I didn?t reset the idle mixture screws on my fuel injected 64? Corvair (that?s right I put a RSA-5 on it) when I drove from Glendale to Mammoth Lake. Yea it ran a little richer up there, but no big deal. Some of you guys weren?t around then but cars had carburetors on them with no feed back circuits to compensate for temperature and altitude. Did the engines run like the cars today? No. Did we get by with it? Yes. Was it dead simple and give good service? Yes. I guess that now with all the EFI in cars most pilots expect the operation to be the same as in their daily driver. But the present aircraft FI technology is not EFI. I really don?t think it?s necessary either. Can some of these idle issues be addressed with the present FI systems? Yes. Would it be cost effective and give better value to the customer? Probably not.

So getting back to leaning on the ground. If it makes you feel good, do it. If the idle mixture is rich all the time and you lean the mixture on the ground to compensate for it, why not set the idle mixture correctly so the engine runs correctly at idle. Then when your in the air at a reduced power the engine will run correctly with the mixture full rich.
 
Very dangerous advice (Carburator)

My home field KAEJ is at 8,000 ft, and can see density altitudes over 12,000 ft in the summer. Set your idle mixture to run correctly with no leaning at this field, and fly to sea level. Hope you like the sound of silence!

We see people taking off without leaning properly, and fortunately they usually don't get high enough to hurt themselves. This does give the locals a good supply of spare parts.

Roger

ps. Don't know much about Airflow Performance- maybe it can compensate.
 
I start my carbureted O-360 with the mixture out about an inch. Basically where it should be when I verify the mixture during the runup.

No problems going to sea level or below (Death Valley).

I had a very competent mechanic set the idle mixture/RPM.
 
Hi Ron,

I'm talking about setting the idle mixture at a high field with the knob all the way in. Now you will be way too lean at sea level with no way to enrich the mixture.

You are right, your mechanic is the best!

Roger
 
Very dangerous advice (Carburetor)
Click to expand...

Roger, who is giving dangerous advice?
No one advises to set the idle mixture at high altitude with the red knob all the way in.

So for those that have home fields above 5000 feet and then fly to sea level, you would have to set your idle mixture a bit on the rich side.
Click to expand...
 
Ernst,
I did see that response after I had written my reply, But I would still believe that there is no reason to set up the idle for anything other than sea level. The plane might be sold or lent to someone who doesn't discover the problem until at lower altitude.

Roger
 
OK, I do not believe I have asked an ignorant question today so I have one free one allowed.

Assumption: Carburetor. Field elevation well above sea level.

Does one pull the mixture out X amount and then set everything or some other process?

I really cannot recall how it was dome with my engine.
 
Roger,
one of us is confused, probably me.

My point is that no one is advocating to set the idle mixture for anything other than sea level. As Don pointed out if you are over 5000 set the
idle mixture a bit on the rich side.
Click to expand...
Click to expand...
So my question to you: who is giving dangerous advice?
 
Ron Lee said:
OK, I do not believe I have asked an ignorant question today so I have one free one allowed.

Assumption: Carburetor. Field elevation well above sea level.

Does one pull the mixture out X amount and then set everything or some other process?

I really cannot recall how it was dome with my engine.
Click to expand...

I seems that most do the same around here 4600'. Start the engine with knob full in..............then pull out about 3/4" right after start. If you don't you can tell the difference, especially once you start taxiing.
 
Ron, here is the procedure from Lycoming.

e. Idle Speed and Mixture Adjustment.
(1) Start the engine and warm up in the usual manner until oil and cylinder head temperatures are
normal.
(2) Checkmagnetos. If the ?mag-drop?is normal, proceed with idle adjustment.
(3) Set throttle stop screw so that the engine idles at the airframe manufacturer?s recommended
idling RPM. If the RPM changes appreciably after making idle mixture adjustment during the
succeeding steps, readjust the idle speed to the desired RPM.
(4) When the idling speed has been stabilized, move the cockpit mixture control lever with a smooth,
steady pull toward the ?Idle Cut-Off?position and observe the tachometer for any change during
the leaning process. Caution must be exercised to return the mixture control to the ?Full Rich?
position before the RPM can drop to a point where the engine cuts out. An increase of more than
50 RPM while ?leaning out?indicates an excessively rich idle mixture. An immediate decrease in
RPM (if not preceded by a momentary increase) indicates the idle mixture is too lean.

If this is done at a high elevation airport, the mixture will be too lean at sea level, so we intentionally set richer than this recommendation and use that red knob for taxi and takeoff.

Roger
 
N427EF said:
...My point is that no one is advocating to set the idle mixture for anything other than sea level....
Click to expand...

That's exactly what I advocate.

I feel it should be set to allow for a cold day at sea level during a high pressure period. That is, significantly more fuel flow than what standard day conditions would call for. If it's not, then when those unusual conditions exist, it'll be too lean with no capability available to adjust the mixture richer and prevent damage.

At high altitudes with a carb - this is what I do here in Colorado with my Cessna 180 - start at full rich, once it's stable, lean about an inch. During run up, lean to best power. I check it during climb out and frequently will lean it further as I go.

Dave
 
Agreed

I fully agree with what has been said by everyone.

I would still like to know why mntclimber put dangerous advice in the heading of his post or who he was referring to?
 
There are TWO topics beings discussed for carbed engines.

1) How do you start the engine at high altitude?

2) How do you set it up at high altitude so it works fine at sea level?

I am not sure that there is a good answer for #2 other than make it a bit rich.

For #1, I start with the engine mixture knob out to where it normally should be for a proper mixture at my altitude. I do not understand starting full rich since that will not be the ideal combustion mixture. It may lead to plug lead fouling.
 
For #1, I start with the engine mixture knob out to where it normally should be for a proper mixture at my altitude. I do not understand starting full rich since that will not be the ideal combustion mixture. It may lead to plug lead fouling.
Click to expand...

It must be like a "choke". I just know it works well..........and it's only for a few seconds. When I first started flying the RV, I was having to clear the plugs once and a while during the mag check. I soon got use using my EHT (cylinder#3 only) gauge, and in-flight adjusting of the mixture, to completely eliminate any plug fouling.

L.Adamson
 
Lets make this simple:

1. Set the mixture on the servo or carb to produce the correct idle behavior AT SEA LEVEL per mfg.

2. "If required" lean to suit higher DA conditions with the red knob.
 
I am in complete agreement that the mixture must be set for sea level, and leaned at higher altitudes. I also believe that advising to adjusting to "a bit lean if adjusting at higher altitudes is ambiguous, at best. Is that 1/4 turn at 5000, 2 turns if density altitude is 12,000?

I've learned a bit from this post, and will never use words like "dangerous" again. Too inflammatory. I think spending the last 30 years flying at really high density altitudes I've seen too many accidents from leaning and mixture issues.

And to be honest, early on I was a slow learner, and gave the local laundry my share of business!

Roger
 
Toobuilder said:
Lets make this simple:

1. Set the mixture on the servo or carb to produce the correct idle behavior AT SEA LEVEL per mfg.

2. "If required" lean to suit higher DA conditions with the red knob.
Click to expand...

Makes perfect sense to me. However, referring back to Don's post (#18), he seems to indicate that there would be no significant change in the idle mixture screw setting unless you had around 5,000 feet or more of elevation change or a 50 degree or more temperature swing. Probably no reason to adjust things for most of us as long as it was set correctly before and we reside at an airport between 0 to 5,000 feet elevation and were not experiencing extreme temperatures at the time the idle mixture screw was set. In other words, the system has some flexibility.

I think we have succesfully beaten this subject death. As you were...

erich
 
erich weaver said:
Makes perfect sense to me. However, referring back to Don's post (#18)...
Click to expand...

Agreed. As long as people out west (like us) are aware that we may have a huge DA change from airport to airport. Also, the next time we fly to a near sea level airport for breakfast, it may not hurt to "spot check" the idle mixture by slowly pulling the mixture at shutdown and see what kind of an RPM rise you get before it quits. If you get zero, you're likely too lean; if its significant, you may be fat. Simple stuff.
 
Idle mixture change with altitude

OK here are some facts. This is how our fuel injection system works. Lets say at sea level it is 70 degrees F. At 7000 ft it?s 80 degrees F. Using the standard day pressures for sea level and for 7000 feet our fuel injection system will have an error of about 13% in the fuel air ratio. At idle, most 360?s run 1.2 to 1.5 GPH. That means that if you traveled from the sea level location to the 7000 ft location you would have to lean the mixture at idle 0.15 to 0.19 GPH. You can?t see this accurately on the flow meter in the airplane. Also the engine will run with a +/- 2% change in fuel air ratio, so if you took the 4% out of the flow the change in flow would be 0.1 to 0.13 GPH. That?s a tenth of a GPH. The reality of this is, I just don?t see how the engine will quit as some have stated. This is not saying that there are other factors affecting the engine performance with the altitude change like fuel vapor and under cowl temperature.

Carburetors and other types fuel injection systems may act completely different so I cannot comment on their operation with altitude change.


Don
 
Don, I don't think anyone is suggesting that the engine will "quit" because it is too fat at higher DA, rather, it is probably not a good idea to set the mixture (at the servo/carb) for a hot summer day in Flagstaff, then expect it to perform correctly six months later at Death Valley in the dead of winter. This is especially true if the mechanic in Flagstaff sets it on the "lean" side of the range to begin with.

Just to be clear, are you suggesting that the Airflow servo can be set at any (realistic) altitude and DA and still function properly at sea level without readjustment?
 
Idle Mixture Adjustment

No, I?m saying that the idle mixture (full rich mixture also) will change with the square root of the change in air density. Therefore some idle mixture adjustment may be necessary from summer operation to winter operation. When flying from sea level to a field at 7000 feet as in the above example, the amount of air density change is not enough to make a significant change in the fuel air ratio that one would have to readjust the idle mixture. OK there are some of you that fly from 12000 feet to sea level. In that case you should set your idle mixture richer than best idle performance at 12000 ft and lean with the mixture control in the cockpit to allow the engine to run correctly at 12000 ft so that when the flight lands at sea level the engine should run reasonably well with the mixture full rich.

Getting back to the original post, it was said that there was contradiction in leaning idle mixture on the ground with the mixture control in the cockpit. Our consensus is that there is an idle mixture adjustment on the fuel control unit for a reason. Except for the certain instances of unusual operation at high DA, our suggestion and instructions in our Installation and Service Manual is that the idle mixture should be set correctly with the idle mixture adjustment, not with the mixture control in the cockpit. This allows the fuel control to operate correctly under all loads and the pilot does not have to remember to put the mixture back full rich for take-off. We see many fuel injection servos in our shop set excessively rich at idle and the pilot uses the mixture control in the cockpit to compensate for the overly rich mixture. If anyone here on the VAF that is running Airflow Performance fuel injection has additional questions on this subject, please feel free to call me directly for clarification. Any of you that are interested in learning more on the operation of this type of mechanical fuel injection systems (Precision included) please inquire about our Fuel Injection 101 class scheduled for March 1-3, 2013.


Don
 
OK Don, thanks for that. What you are saying is consistent with my understanding.

That said, and re reading post number 1 again, I think we may be hung up on the word "need". No, there is no "need" to augment a properly set servo/carb mixture with the red knob at "normal" DA. The engine will respond properly to all transients just as it is supposed to do.

However, you will likely agree that the engine can be leaned further (with the red knob) if the pilot "wishes" to do so for ground ops, and this additional leaning will not hurt the engine. True statement?
 
Toobuilder said:
OK Don, thanks for that. What you are saying is consistent with my understanding.

That said, and re reading post number 1 again, I think we may be hung up on the word "need". No, there is no "need" to augment a properly set servo/carb mixture with the red knob at "normal" DA. The engine will respond properly to all transients just as it is supposed to do.

However, you will likely agree that the engine can be leaned further (with the red knob) if the pilot "wishes" to do so for ground ops, and this additional leaning will not hurt the engine. True statement?
Click to expand...



True.


Don
 
You must log in or register to reply here.
Back
Top