In rec.aviation.owning Stan Prevost wrote:
: If the mixture is set to spec, it is not necessary to lean for ground ops,
: since it is already lean enough to prevent plug fouling. Ground leaning is
: effective only if leaned back to the edge of idle cutoff, anyway.

: The Lycoming manual doesn't seem to have any tables for adjusting RPM rise
: for density altitude. If it is leaned to the 5RPM rise spec at a high
: altitude airport, I wonder if it might be too lean at a low-altitude
: airport, with no way to enrichen it.

Not to mention seasonal variation. With temperatures in Virginia in the 60s
(!) the past weeks it's difficult to even do it for winter/summer... not to mention
density altitude.

I ground lean mine... typically right on the edge of idle cutoff. It's enough
so that anything over 1200 RPM will cause the engine to stumble. That way it will be
periodically run extra-lean during the taxi and help reduce plug fouling. Can't hurt
the engine with leaning at such low power and it's impossible to runup or takeoff
without enrichening.

-Cory


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* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
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