Do you lean for take off ?

Oh by the way for the full power mixture check you're watching MP and listening for roughness and the EGT needle if you've got one. I do. It's more a confirmation something's not way out of whack in the carb system after the partial power setting is set, and you mentally note where you were set and adjust to either side making sure you don't notice a big power change that's unexpected. RPM is limited out at full throttle so it's useless.
 
My POH says ...

Mixture -- Full Rich (unless engine is rough)

Crazy huh?
 
txflyer said:
Departing KHRX this morning, I did my runup and leaned it to clear the right mag because it was running a little rough. The engine sounded so good I just left it leaned out and took off. Keep in mind, I normally operate from 300 ASL.

Elevation there is ~4000. It was cold so DA wasn't much a factor, but the engine liked it better leaned out.

Did I commit a no-no? :dunno:
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No, not really, but unless you had an engine monitor you may have put yourself at a bit of a risk if you didn't know where you were leaned to. For takeoff if leaning is indicated I lean 200°-250° ROP. I have full power and a good margin on detonation.
 
txflyer said:
My POH says ...

Mixture -- Full Rich (unless engine is rough)

Crazy huh?
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In the amplified description section, under "Climb", it probably tells you to lean above 5,000' (and although it doesn't specify, I interpret that to mean density altitude) for engine smoothness and max power.

Those Cessna owners manuals of the '50s and '60s were notoriously skimpy and superficial, especially on the issue of power management.
 
It is interesting that a Rotax, by bing 64 carb design takes off at full rich at high DA and unlike a Conti or a Lyc there seem to be no issues.

92% throttle or above for the bings there is no leaning by design and same for the new injected 912, yet the power seems good.

Some argue that at high DA the pressure differential is not great enough to fully raise the needle and give full control to the main circuit so it is possible that I am not really full rich. The injected model needs to retard the throttle below 92% got go to econo mode where leaning occurs.

As I climb through 12,000' for 14,000' WOT and full rich are required yet the Rotax remains happy.
 
Ron Levy said:
Then I'd go to the Operator's Manual on the engine from Continental. As far as I can tell, that's not on their web site, so you have to contact TCM to get that.

Continental Motors, Inc. - 2039 Broad Street Mobile, AL 36615
Phone: 251-438-3411 | 800-718-3411 | Mailing Address: PO Box 90 Mobile, AL 36601
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That reminds me: I have seen POHs that say to consult the engine manual for leaning instructions, but I have NEVER seen an engine manual in a rental plane.

Like they say, "We live in an imperfect world."
 
Palmpilot said:
That reminds me: I have seen POHs that say to consult the engine manual for leaning instructions, but I have NEVER seen an engine manual in a rental plane.

Like they say, "We live in an imperfect world."
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Lots of pilots who rent get their own copy of the Information Manual on what they rent. No reason not to do the same for the engine on the plane they rent.
 
If the owner doesn't care enough about their engine to provide the manual, I'm sure as hell not buying it. I'm a renter, why should I care more than they?:dunno:
 
This is what I found in my O/IO/HIO-540 manual:

On engines with manual mixture control, maintain mixture control in "Full Rich" position for rated take-off, climb and maximum cruise powers (above approximately 75%). However, during take-off from high elevation airport or during climb, roughness or loss of power may result from over-richness. In such a case adjust mixture control only enough to obtain smooth operation - not for economy. Observe instruments for temperature rise. Rough operation due to over-rich fuel/air mixture is most likely to be encountered in carbureted engines at altitude above 5,000 feet.
Click to expand...
 
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BGF_Yankee said:
This is what I found in my O/IO/HIO-540 manual:
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Verbatim the same in my O-360 manual.

Of course, this is the same manual that says mixture should be left "full rich" for ground running and warm-up, so ...

salt_zpsmqnyqogh.jpg
 
That photo speaks volumes!
 
On a hot summer day in Denver, density altitudes are typically 8000' or even higher. If you don't lean, you aren't going to have the power you need to operate safely. So even if your POH doesn't address leaning, you need to lean.

In case you don't know how (and this is for a normally aspirated engine), what you have to do is "find peak". You can find peak at full throttle rpm or runup rpm. Full throttle runups are a hassle so we usually do it at runup rpm. Set the throttle and pull the lean knob out until the rpms begin to drop. Now increase rpm to the point where it is back to maximum (for that throttle setting of course). That is peak. Now, enrichen "a bit". Not much if you are at 8000' density, but if you want to be cautious the 'standard amount' is three half turns. That will work ok and you wont be too lean, nor so rich as to lose much power. Works for both constant speed and fixed pitch props.

If you don't believe you can do it at runup rpm, do it at full throttle rpm and compare the results. They usually result in the lean knob being in the same place (which is why we do it at runup RPM).

If you go up to Leadville on a hot summer day, the density altitude is over 12000', and you don't want to enrichen a bit, just take off at the "find peak" setting. You need the engine to be running at its maximum possible power (which isn't much). Up that high, full power is going to be at peak. No need to richen.

Hope that helps!
 
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If you have an engine monitor you can just lean till your EGTs are 150 degrees rich of peak....
 
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