Matt wrote:
: Hi everyone. I have a leaning question. The POH for my 152 says that the
: mixture should be leaned to best power after passing 3000 feet in the climb.
: However in other places in the POH (and the Lycoming site) they say not to
: lean when at 75% power or higher in cruise. My question: Is the engine
: developing less than 75% power during the climb; and is this why leaning in
: the climb is OK? Does this guidance in the POH seem contradictory to anyone
: except me?

: Thanks for all your help.

Few things have has much disinformation (DI) and old-wives-tales (OWT) as
aviation. Few things in aviation have as much DI and OWT as engine leaning. I
suggest you read through some of Deakin's articles on www.avweb.com to clarify.

My personal climb-leaning is to lean to a constant EGT. Hold whatever takeoff
EGT is until through 8000'. At that point it's impossible to go over 75% on a
normally aspirated plane.

Even though with the RPM low in a climb, it's probably not possible to exceed
75% power, it's the worst kind of "75% power"... low RPM max MP. Given the low speed
and high angle of attack in a climb, I wouldn't lean to best power until a bit higher
than 3000'. Of course, if it's in the POH is must be gospel.... always driven by the
goals of long engine life, low fuel burn, minimum maintenance, and least money
expended... never by marketing, performance numbers, or band-aid workaround covering
other problems. Nope... never. ;-)

-Cory



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