I have never, ever heard of LOP discussions talk about peak RPM. Why
would that ever even enter the conversation?


Some trainers, I can not recall whether it was the Cessna 150M or the 152
and can not immediately find the POH, authorized slightly lean of peak RPM
operation at 60 percent power or less. Both aircraft have fixed pitch
props, and only a tachometer--no EGT or analyzer.

Interestingly, the statement was in an area pertaining to training
operations (Chapter 6 or 7 IIRC) rather than in the pace where it would have
been expected. I seem to recall 25 RPM lean of peak, although it could have
been slightly more, and I certainly would not go out and try it without
further reference to the manual. In fact, even though a number of
contributors have pointed out that engines are quite tolerant when operating
at low power, it has been many years and it would be a good idea to verfiy
that the POH is still current.

BTW, when the lean operation was used where applicable, the aircraft became
VERY economical to operate--and the plugs probably lasted much longer as
well.

Peter