More leaning questions!

cocolos

cocolos

Pre-takeoff checklist
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cocolos
Hi,

So I only have one EGT and one CHT, which from what I've read is not really enough to accurately use them for leaning. So I basically just lean until rough the richen a bit.

Question 1: Do you have a harder time leaning when you have noise canceling headphones on? if so do you turn off the noise canceling?

Question 2: When at altitude say 10k and airport is at 7k do you wait until PTA to lean to max power(assuming you're leaned LOP or ROP)? Do you simply just enrichen until it's at max power at PTA? or do you enrichen at 10k then lean to max power at 7k? If this is confusing please let me know so I can clarify.

As always thanks!
 
great question. as far as the noise cancelling headphones the advice I get is to have your feet on the floor and feel for vibrations. Lean till you get vibrations and richen the mixture again till the vibrations disappear.
 
Maybe TPA (traffic pattern altitude)?
 
Geico266 said:
Okay, I'm not awake yet... what is PTA?
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When I was a kid it was a group of teachers and parents who discussed things once a month and smoke cigarettes in the school cafeteria. What that has to do with aviation, I do not know, unless those were not real cigarettes they were smoking, it being the 60's and 70's and everything.

I think he meant TPA as ScottK pointed out.
 
cocolos said:
So I only have one E.GT and one CHT, which from what I've read is not really enough to accurately use them for leaning. So I basically just lean until rough the richen a bit.
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Good technique

Question 1: Do you have a harder time leaning when you have noise canceling headphones on? if so do you turn off the noise canceling?
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No.

Question 2: When at altitude say 10k and airport is at 7k do you wait until PTA to lean to max power(assuming you're leaned LOP or ROP)? Do you simply just enrichen until it's at max power at PTA? or do you enrichen at 10k then lean to max power at 7k? If this is confusing please let me know so I can clarify.
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None of the above. I leave it where it is, and enrich only if I have to go around.
 
cocolos said:
Question 2: When at altitude say 10k and airport is at 7k do you wait until PTA to lean to max power(assuming you're leaned LOP or ROP)? Do you simply just enrichen until it's at max power at PTA? or do you enrichen at 10k then lean to max power at 7k? If this is confusing please let me know so I can clarify.

As always thanks!
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Landing, like Ron says, leave mixture set. Don't go full rich in the pattern. Try it for a second and you'll know why. ;)

Take off at that altitude you should lean to Max power while rolling on the runway. That's what I do anyway. Above 7,500 you can't lean too much in a non trubo engine. Don't wait until reaching PTA, and certainly do no take off full rich. :no:
 
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douglas393 said:
When I was a kid it was a group of teachers and parents who discussed things once a month and smoke cigarettes in the school cafeteria. What that has to do with aviation, I do not know, unless those were not real cigarettes they were smoking, it being the 60's and 70's and everything.

I think he meant TPA as ScottK pointed out.
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:rofl:

I knew I was in trouble asking. ;)

I'm awake now, kinda. Only had 2 cups of coffee. I should just start an IV. :lol:
 
Geico266 said:
Landing, like Ron says, leave mixture set. Don't go full rich in the pattern. Try it for a second and you'll know why. ;)

Take off at that altitude you should lean to Max power while rolling on the runway. That's what I do anyway. Above 7,500 you can't lean too much in a non trubo engine. Don't wait until reaching PTA, and certainly do no take off full rich. :no:
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Please try it well above TPA.

You can't lean so much as to cause detonation at high altitude, but you certainly can lean too much to get off the ground.

Leaning while rolling is only necessary on a soft or loose surface. On pavement, you can do a full-power run-up while stopped, and reduce you variables.

Avoid the temptation to find best mixture at low power (especially with a CS prop), or you'll flood the engine, particularly if it's injected. Don't ask how I know that....
 
cocolos said:
Hi,

So I only have one EGT and one CHT, which from what I've read is not really enough to accurately use them for leaning. So I basically just lean until rough the richen a bit.

Question 1: Do you have a harder time leaning when you have noise canceling headphones on? if so do you turn off the noise canceling?

Question 2: When at altitude say 10k and airport is at 7k do you wait until PTA to lean to max power(assuming you're leaned LOP or ROP)? Do you simply just enrichen until it's at max power at PTA? or do you enrichen at 10k then lean to max power at 7k? If this is confusing please let me know so I can clarify.
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Question 1: Noise canceling headphones help me hear the important engine noises. Leaning is by feel as in feel the vibration.

Question 2: The high density altitude operations gurus around here say to lean for max power while approaching the airport. That said, three thousand feet isn't going to make a lot of difference in the example you gave. Here in Denver we lean for max power prior to departure and then generally don't touch it again as long as we don't go above eight or nine thousand feet (or fly to the lowlands somewhere).

As for my own leaning? I go max rich prior to landing. Of course the Frankenkota is turbocharged so that's the correct thing to do.
 
cocolos said:
Question 1: Do you have a harder time leaning when you have noise canceling headphones on? if so do you turn off the noise canceling?
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No. Not even a little.

Question 2: When at altitude say 10k and airport is at 7k do you wait until PTA to lean to max power(assuming you're leaned LOP or ROP)? Do you simply just enrichen until it's at max power at PTA?
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There are two problems with "real" leaning on the way down: (1) you are at a reduced power level; (2) whether on the descent or at TPA, there are other tasks that should be taking your attention.

Assuming you are at least at run-up power, #1 can be resolved, in theory, by re-leaning at that power level on the way down and estimate the additional enrichening it by an estmated figure for the needs of full power in the case of a go-around in the same way as you would on the ground for takeoff (assuming you're using the method for leaning for takeoff at run-up power rather than full power).

I've done it but found it more of a hassle than it's worth; a higher distraction cost than the estimated benefit it provides. Instead, I guestimate the enrichening on the way down and guestimate the setting I will need for a potential go-around, being prepared to tweak that setting as necessary in the case of a real go-around. The advantages are that, with very little experience, you will typically be close enough (in the course of 20 years in Colorado I never had to tweak the mixture for a go-around) and the distraction factor is about nil.
 
if there is ever a question, Lean Forward
 
Sounds like for question simply enrich it a bit(couple twist) at 10k then proceed to land. correct?
 
midlifeflyer said:
Pretty much. It will generally get you close enough.
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I flooded an engine following that procedure.

It quit on touchdown on a high altitude runway with no taxiways and wouldn't restart until it had cooled for an hour.

Adjust mixture at high power, and you'll avoid that problem.
 
MAKG1 said:
I flooded an engine following that procedure.

It quit on touchdown on a high altitude runway with no taxiways and wouldn't restart until it had cooled for an hour.

Adjust mixture at high power, and you'll avoid that problem.
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Yes I meant to add that as well. So adjust mixture at high power by just enriching it a bit.
 
Now lets say your at 10k coming down to sea level would you just enrich a couple twist every 1000 ft if you're descending at 500ft/min? what about desceding at 1000ft/min would you just enrich an 1inch at a time or something? (assuming you're in low power setting for descent)
 
At sea level, you'll likely cruise at high power during descent, so lean normally. Go to full rich at 3000 feet, or prior to landing.
 
MAKG1 said:
At sea level, you'll likely cruise at high power during descent, so lean normally. Go to full rich at 3000 feet, or prior to landing.
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ok so same thing as 10k to 7k scenario but full rich at 3k or so. Cool thanks!
 
Field elevation of 7k feet, mixture should be leaned prior to takeoff, at startup, then after warmup, and run-up it should be set for best power, and then enrichened just a tad. and left alone untill climbing past TPA.
At that altitude, you don't really want to go to full rich. Even when doing the "GUMP" check in preparation to land.
Flying out of MVI in July, at 8am local, DA is usually around 10k feet. Do you really want full rich for takeoff at that altitude?

That said, I usually lean for best power when descending to TPA as part of the GUMP check.
 
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MAKG1 said:
At sea level, you'll likely cruise at high power during descent, so lean normally. Go to full rich at 3000 feet, or prior to landing.
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I'm never full rich except for start up. (and now as I'm breaking in cylinders - grrrrrr.)

Disclosure - I have CHT and EGT on all 6 cylinders, and a functioning brain.
 
bluerooster said:
Field elevation of 7k feet, mixture should be leaned prior to takeoff, at startup, then after warmup, and run-up it should be set for best power, and then enrichened just a tad. and left alone untill climbing past TPA.
At that altitude, you don't really want to go to full rich. Even when doing the "GUMP" check in preparation to land.
Flying out of MVI in July, at 8am local, DA is usually around 10k feet. Do you really want full rich for takeoff at that altitude?

That said, I usually lean for best power when descending to TPA as part of the GUMP check.
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I had a scenario where you would be going from sea level to an airport at 7k not taking off from one.
 
cocolos said:
ok so same thing as 10k to 7k scenario but full rich at 3k or so. Cool thanks!
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Cool is right -- EGT's will go way down. But that means you're likely to load up the plugs big time, and if you then need power to go around, it may not be there. Keep the EGT's up to prevent that, and that means leaving the engine leaned until you need more power.
 
Ron Levy said:
Cool is right -- EGT's will go way down. But that means you're likely to load up the plugs big time, and if you then need power to go around, it may not be there. Keep the EGT's up to prevent that, and that means leaving the engine leaned until you need more power.
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hmm okay so instead just leave it leaned and until it start running rough enrichen?
 
Ron Levy said:
Yup..
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The one issue with that, is depending how much you've reduced the throttle, and descended, it will still run and smooth, but when you go to put in the power it can get REAL quiet. I gradually enrichen as I descend, but I also know where my mixture knob is supposed to be at, at varying altitudes.
 
cocolos said:
hmm okay so instead just leave it leaned and until it start running rough enrichen?
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That's fine below 75% power. If you descend at constant throttle, the power will go up as you lose altitude. Full throttle leaned is fine at 7000 feet, but it's a problem at 1000.

Manage the throttle to below 75% power and you can do that. But in a go-around, you must firewall the red knob first. Then the blue knob if you have one, then black. Below 3000 only.

You will get a lot of conflicting advice here. The POH differs from up to date engine manufacturers' recommendations in some respects. Do not try to run lean of peak without an engine analyzer. You need EGT and CHT on every cylinder.
 
MAKG1 said:
That's fine below 75% power. If you descend at constant throttle, the power will go up as you lose altitude. Full throttle leaned is fine at 7000 feet, but it's a problem at 1000.

Manage the throttle to below 75% power and you can do that. But in a go-around, you must firewall the red knob first. Then the blue knob if you have one, then black. Below 3000 only.

You will get a lot of conflicting advice here. The POH differs from up to date engine manufacturers' recommendations in some respects. Do not try to run lean of peak without an engine analyzer. You need EGT and CHT on every cylinder.
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Ok. Yes I am having trouble deciphering all the different methods of doing this, so let me recap:

1. taking off from high altitude airport full power and lean to max RPM (fixed-pitch)

2. landing at a high altitude at cruise power enrich it a couple of twist.

3. don't lean at low rpm.


that sound about right? anything I miss?
 
#2 has given me some trouble with flooding on injected engines. I've gotten away with it on carbureted engines, but it's still not clear to me that it's better than leaving it lean unless a go-around is necessary.
 
cocolos said:
So I only have one EGT and one CHT, which from what I've read is not really enough to accurately use them for leaning. So I basically just lean until rough the richen a bit.
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Okay, have you bothered to watch the EGT while you do that? What have you read that makes you assume it's not enough instrumentation to use for that purpose. I mean, that's basically why the instrument was installed in the first place and there's a real good chance that it's going to give you more information than turning off your noise cancelling headset and placing your feet on the floor.
 
Silvaire said:
Okay, have you bothered to watch the EGT while you do that? What have you read that makes you assume it's not enough instrumentation to use for that purpose. I mean, that's basically why the instrument was installed in the first place and there's a real good chance that it's going to give you more information than turning off your noise cancelling headset and placing your feet on the floor.
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I have not paid too much attention mostly because of what I read that it just wasn't enough to know where all the cylinders were at. So would you suggest looking at it until I reach ROP or LOP or peak on EGT?
 
MAKG1 said:
I flooded an engine following that procedure.
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OTOH, I didn't in the 20 years I flew in Colorado and, as I said, haven't even needed a tweak ona go-around.

But your point is well-taken and it's why I added the caution,
The advantages are that, with very little experience, you will typically be close enough
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to my original comment on the subject.

Sounds like you enrichened way too much and didn't guestimate even close. Chances are if you used the same procedure the next time, you'd be much, much closer.

Obviously it helps when you have taken off from high-altitude airports. Then you at least have a knowledge basis for a target for landing. And, of course, the more you do it, the easier and more accurate it gets.
 
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cocolos said:
I have not paid too much attention mostly because of what I read that it just wasn't enough to know where all the cylinders were at. So would you suggest looking at it until I reach ROP or LOP or peak on EGT?
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Yes, that's what it's there for. What you are reading is probably in regards to operating LOP which is not what you are doing or attempting to do. It's true that not all cylinders are going to peak at the exact same setting but even with a carbureted engine they are not going to be so far off as to make a single EGT worthless for the purpose of setting ROP operation.

I'm not sure what you're flying but if it's fixed pitch then just slowly lean the mixture while watching the EGT and RPM and see how closely together they peak and if the roughness starts after the EGT peak. It's going to give you a much finer indication than just using your ear.
 
midlifeflyer said:
Sounds like you enrichened way too much and didn't guestimate even close. Chances are if you used the same procedure the next time, you'd be much, much closer.
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It could be....it was the first time with an injected engine and a flow meter at high density altitude. I have very little experience with injected engines, and IO-360s are notorious for poor fuel flow management at low throttle.

The next time, I'll try it at an airport with taxiways and maybe a mechanic just in case I drain the battery screwing up hot/flooded starts. And maybe it might be a good idea to grab an instructor at sea level and intentionally flood (perhaps, overprime) a 172SP or the 177RG to practice those hot starts.

Obviously, I enriched it way too much if I flooded it....it didn't seem like I added that much fuel; just a few turns descending from 13,000 feet over the Sierra to 7,000 at Lee Vining.
 
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cocolos said:
Now lets say your at 10k coming down to sea level would you just enrich a couple twist every 1000 ft if you're descending at 500ft/min? what about desceding at 1000ft/min would you just enrich an 1inch at a time or something? (assuming you're in low power setting for descent)
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The method I taught (and used) was to descend until the engine told me that I was running too lean by beginning to run rough. Enrich until it smoothed out, continued descent until engine said "Hey, dummy" again, rinse and repeat until I reached approach altitude.

Bob Gardner
 
bobmrg said:
The method I taught (and used) was to descend until the engine told me that I was running too lean by beginning to run rough. Enrich until it smoothed out, continued descent until engine said "Hey, dummy" again, rinse and repeat until I reached approach altitude.

Bob Gardner
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Very similar to Davids method of leaning

Descend till the engine scares you and push the red knob forward till your not scared anymore.
 
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