Leaning out the mixture on the ground Op's

[gege21]

Hi fellow flyers,

After reading all the posts about how to lean, I just wanted some advices to properly lean out the mixture for ground operations.

1- In the manual it is said "set the RPM at 1200 rpm then lean out the mixture to get maximum RPM". What this means ?
Is there, after setting 1200 RPM with the throttle, to lean out to get lower RPM (i.e. just a bit above 1000 RPM) just enough to have the engine running smooth ? Or is there to lean out the mixture just to see the RPM decrease a little when at 1200 RPM and lean in to stay at 1200 RPM then pulling the throttle to get a reasonable RPM (i.e. 850/900 rpm) to be able to move the plane with slow speed.
2- When the engine is cold, is there risky to set the RPM at 1200 rpm to make the leaning process, then pulling the throttle back under 1000 RPM ? As all the leaning process take less 1 minute.

Any advices well appreciated.

Cheers
Gerard

[flapman]

Set 1200 RPM with mixture full rich. After the RPM is set, do not move throttle lever. Lean engine by very slowly pulling mixture lever away from full rich towards idle cutoff. As you move mixture towards lean, RPM will increase very slightly (perhaps 50 RPM). When RPM has reached it's highest value for the given throttle lever position, you have "leaned for maximum RPM."

At this point, do not change the position of the mixture lever, and use throttle to set power as desired.

[Piper_EEWL]

What I usually do on the ground is just pull the mixture lever out till the engine starts running rough. Then add some mixture till smooth running is achieved. This will probably lead to the engine having a hard time gaining rpm when you try to taxi but then just add some more mixture. I know this is not exactly following the procedure but during warmup you will not harm the engine if you do that. And it's usually rather effective prohibiting the spark plugs from fouling.

One more more thought to consider is that if you do it that way the engine will for sure give you a warning in noise and rough running when adding full throttle so you don't accidentally take of with the mixture leaned out.

Happy flying

[gege21]

Set 1200 RPM with mixture full rich. After the RPM is set, do not move throttle lever. Lean engine by very slowly pulling mixture lever away from full rich towards idle cutoff. As you move mixture towards lean, RPM will increase very slightly (perhaps 50 RPM). When RPM has reached it's highest value for the given throttle lever position, you have "leaned for maximum RPM."

At this point, do not change the position of the mixture lever, and use throttle to set power as desired.

Thank you very much for your procedure advice. but for me it is very hard to see the rpm to raise for 50 rpm even when I take the look close to the rpm gauge... I believe I never saw the rpm increased when at 1200 and leaning towards idle cut off just to see an increased rpm even a little bit.

I'm going again to take a look more accurately.

Anyway I just hope your advice is not as real world I whished just to know how to do with virtual sim on the A2A C172.
Thank you very much

Cheers
Gerard

[gege21]

What I usually do on the ground is just pull the mixture lever out till the engine starts running rough. Then add some mixture till smooth running is achieved. This will probably lead to the engine having a hard time gaining rpm when you try to taxi but then just add some more mixture. I know this is not exactly following the procedure but during warmup you will not harm the engine if you do that. And it's usually rather effective prohibiting the spark plugs from fouling.

One more more thought to consider is that if you do it that way the engine will for sure give you a warning in noise and rough running when adding full throttle so you don't accidentally take of with the mixture leaned out.

Happy flying

Ok, that's what I was doing to lean out. I settled the rpm at 1200 rpm then lean towards idle cut off just to lower the RPM at 1050/1100 before the engine become rough then pull back the throttle below 1000 rpm. Doing so I got rarely fouled spark plugs even if sometimes the park plugs are a little fouled, during the mag test I could clear easily this issue.

Thank you very much to both for your advice process leaning.

Have a nice and happy day
Cheers
Gerard

[Piper_EEWL]

You're welcome! Just remember that at idle you will not hurt the engine by leaning out because the power setting is very low and the temperatures are very low too. We do this in real life to to prevent spark plug fouling.

Happy flying

[flapman]

My advice is real world, and works in the sim too. The sim is designed to behave as close as possible to the real thing. I have time flying the real aircraft, as an instructor too. In the sim, you can expect to pull the mixture as far back as about 50% to start seeing the RPM rise. I remember... as a student.. and later watching other students... as an instructor, the fear that we develop of the big red knob.

While what we're talking about is procedure, in practice I follow Piper's advice, and lean aggressively past max RPM (lean of peak) while on the ground. I find the A2A spark plugs like to get fouled very easily.

[Piper_EEWL]

I remember... as a student.. and later watching other students... as an instructor, the fear that we develop of the big red knob.

I agree! And a lot of times I feel like it's because pilots don't understand correctly what happens in the engine when you lean.

I find the A2A spark plugs like to get fouled very easily.

I agree. In the real world they don't get fouled that easily in my experience. But it doesn't bother me a bit since it makes flying the sim a bit more challenging

[gege21]

My advice is real world, and works in the sim too. The sim is designed to behave as close as possible to the real thing. I have time flying the real aircraft, as an instructor too. In the sim, you can expect to pull the mixture as far back as about 50% to start seeing the RPM rise. I remember... as a student.. and later watching other students... as an instructor, the fear that we develop of the big red knob.

While what we're talking about is procedure, in practice I follow Piper's advice, and lean aggressively past max RPM (lean of peak) while on the ground. I find the A2A spark plugs like to get fouled very easily.

You have all my respect for your experience and skill. Yes me too I'm going to follow an agressive lean to avoid fouled spark plugs and as you said the A2A C172 is prone to do so with massive wire spark plugs. I wont use the other spark plug fine wire... It is just for the fun and feeling as in RL.

All the best for you and yours for the next coming new Year.

Cheers
Gerard

[gege21]

You're welcome! Just remember that at idle you will not hurt the engine by leaning out because the power setting is very low and the temperatures are very low too. We do this in real life to to prevent spark plug fouling.

Happy flying

Ok so setting the rpm at 1200 don't hurt the cold engine even if the oil is cold and thick (I use 20W50) as 1200 rpm is considered as low rpm...

So I will continue with all your advices ans make as I was already doing.

Thank you very much to both Piper's and flapman for your advices and experience.

have a nice and happy day.

Cheers
Gerard

[Piper_EEWL]

Ok so setting the rpm at 1200 don't hurt the cold engine even if the oil is cold and thick (I use 20W50) as 1200 rpm is considered as low rpm...

I don't think that 1200rpm would harm the engine as long as it's not super cold (I'd say below 0C). But if it's that cold I would preheat the engine anyways.

But I was actually referring to the temperatures in the cylinders (or the EGT) when I'm talking about leaning aggressively.

Anyways happy flying

[gege21]

Oh OK...

So you advice below 0° C you wait for the engine warm up a bit and only when the EGT display a sufficient hot temperature or looking at the oil temperature gauge as soon as the needle begin to raise (say's positive temperature in celsius) above 0° C you engage the leaning process at 1200 RPM ? Making so you don't hurt the engine. It's similar with car's engine in the mind and in average all engine similar motors.

I understand warming up an engine is adviced by cold temperature to avoid brutal shock differential temperature. that's obvious.

Thank you for sharing your experience and advice.

Have a nice evening.
Cheers
Gerard

[Piper_EEWL]

No you can lean out if the engine is below 0C. I personally just wouldn't rev the engine to 1200rpm. You can lean the mixture at 1000rpm as well. Just lean the mixture till rpm starts dropping and then add some more. You will not see an EGT at those low rpm. And since the C172 doesn't have a cylinder head temperature gauge you have to rely on the oiltemperature.

But if it's below 0C I would recommend the electric engine heater. You can install it in the maintenance hangar and then turn it on via the shift+3 menu. It will take a while for it to heat the engine but it can stay plugged in over night. So if you're flying in cold weather just plug it in when you park the aircraft and the engine will be nice and warm the next time you start it up!

[gege21]

Lol sorry Piper I missunderstood what you explained... My English and me that's the worst thing XD.

Now all is very clear : at startup when the engine is cold when outdoor the temp is 0° C or close to this temp, I let the RPM at 1000 maxi or below and make the leaning process at 1000 RPM maxi. As soon as the engine looks warm looking at the oil temperature gauge the needle is at the beginning green arc range, I can rev to 1200 RPM and lean again agressively.

For the heater engine I have the magic stick to heat the oil box. I will test without it and peek the electric engine wired one as you only if the outdoor temp is close to 0° or below.... Just for the fun.

Thank you for the tip when leaving the plane to plug the electric heater to the engine waiting for the next startup...

I will start a new experience with your nice infos.

Have a nice evening
Cheers
Gerard

[Piper_EEWL]

Lol sorry Piper I missunderstood what you explained... My English and me that's the worst thing XD.

Don't worry about that. Your English is just fine! You should hear my French

I will start a new experience with your nice infos.

Yes those A2A planes bring so many hours of enjoyment!

Happy flying