Constant speed props

On Thu, 24 Jun 2004 20:16:30 GMT, Dave S
wrote:

It's possible that the POH's specify rich of peak operation because
that produces the highest cruise speeds, which is often what sells the
airplane.

Corky Scott



The POH (provided by the airframe manufacturer) is not the same as an
operating manual provided by the engine manufacturer.

In regards whether to lean past peak or not and people following
proper procedures, here's what the Cessna Pilot Center Training manual
says:

"In order to lean, you pull back the mixture control knob until the
EGT guage reaches its highest temperature reading (called peak EGT)
and then starts to decrease. At this point enrich the mixture until
it's 50 degrees cooler than peak EGT. You can also lean by pulling
back the mixture control until the RPM just starts to decrease, then
continue leaning until it drops 25-50 rpm." Both instructions are
describing how to adjust the mixture to below peak EGT.

I've seen in Deakin's columns a response from Lycoming (response to
his mixture control columns) to the effect that "we would not
recommend lean of peak to our worst enemy". In light of the Cessna
Training Manual's instructions, I wonder if the two entities (Cessna
and Lycoming) should communicate a bit better?

Corky Scott