Not Leaning on Ground

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woxof

Pre-takeoff checklist
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woxof
A lot of pilots lean the mixture during ground ops to prevent carbon fouling. Some don't or forget. Is it true that the plugs are more likely to foul on a warm day and/or higher density altitude. if so....why?
 
I learned this from direct experience during my first year of ownership. My mag checks were markedly rough after 20-25 hours on the new spark plugs before I learned to lean aggressively after engine start and until the runup check. Knock on wood, I haven't had a rough mag check since (now 2+ years later). Lycoming O-540-J3A5D
 
woxof said:
A lot of pilots lean the mixture during ground ops to prevent carbon fouling. Some don't or forget. Is it true that the plugs are more likely to foul on a warm day and/or higher density altitude. if so....why?
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It's absolutely true and if you operate out west or in the mountains you will quickly learn it is important. I remember the first time I landed a Diamond DA-20 at a mountain runway about 7000 feet up and went full rich because of habit and the checklist and promptly flooded the engine with no room for a restart! I made that landing deadstick, which is a good reason to be on a good approach with margins, too.
 
RyanShort1 said:
It's absolutely true and if you operate out west or in the mountains you will quickly learn it is important. I remember the first time I landed a Diamond DA-20 at a mountain runway about 7000 feet up and went full rich because of habit and the checklist and promptly flooded the engine with no room for a restart! I made that landing deadstick, which is a good reason to be on a good approach with margins, too.
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Seems like if things are set right, the engine shouldn’t quit at full rich even at 15,000 feet, no? Mine certainly doesn’t.
 
Salty said:
Seems like if things are set right, the engine shouldn’t quit at full rich even at 15,000 feet, no? Mine certainly doesn’t.
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I don't know. The plane I flew was a pretty well maintained plane from San Antonio up to the mountains of New Mexico and it was an eye-opening experience. It completely flooded it.
 
If you have an issue with fouling spark plugs on the ground. Consider replacing them with BY plugs. I have had no issue with fouling since I changed mine.
 
Many planes will have fuel flow settings for various manifold pressures

I doubt any of the naturally aspirated planes I have flown would have stayed alight at full rich and 15000 ft

The "full rich at first sign of trouble" is a good rule of thumb, but I think it's important that people understand the mechanics of what's happening when doing that

The atmospheric pressure at 15K feet is less than 1/4 what it is at sea level
 
Dana said:
Uh, no. It's a little over 1/2.
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It helps if I remember meters vs feet! lol

Still.. half-ish air density.. I imagine most engines would suffer at full sea level rich mixture setting.. there's enough variability though in how individual engines are tuned that I imagine some would still run when others would simply flood
 
Tantalum said:
It helps if I remember meters vs feet! lol

Still.. half-ish air density.. I imagine most engines would suffer at full sea level rich mixture setting.. there's enough variability though in how individual engines are tuned that I imagine some would still run when others would simply flood
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Guess I will never know, 13,000 ft is the highest I ever got the Sport. Almost ran out of fuel it took so long...just kidding..:rolleyes:
 
kshaw said:
If you have an issue with fouling spark plugs on the ground. Consider replacing them with BY plugs. I have had no issue with fouling since I changed mine.
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BY plugs? What part number did you use on your plane?
 
All pilots should lean for low power operations. What could go wrong? If you lean too much, the engine will quit: BFD...restart. Good article by Mike Busch in the latest AOPA magazine on sticking valves...in the article, he discusses leaning.

Bob
 
If you lean and the RPM goes up, this is a good thing.
 
woxof said:
A lot of pilots lean the mixture during ground ops to prevent carbon fouling. Some don't or forget. Is it true that the plugs are more likely to foul on a warm day and/or higher density altitude. if so....why?
Click to expand...

Lean aggressively on the ground. You can't cause damage to the engine at low power levels. If you forget to richen it during runup, it will either quit as you increase throttle, or show an increase in RPM with carb heat, which is opposite of what you normally expect. At high density altitudes, you must lean at full power prior to takeoff.
 
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