[M_LIEBERMAN]

I have had my liscence for about 1 year. I tend to like to understand what is going on with things I use. I have asked several experience pilots, read in several books, read in several magazines, and asked a mechanic, what is the proper method to lean an engine. I have a 1976 Cessna 150 (2745J).

For general info, the plane is often flown at 2800 to stay above class D airspace and below class B airspace.

The POH states that at or below 55% power, you lean to peak and lean 50 RPM additional.
(The plane is most often flown at 2800 feet at 2400 RPM, which fits this profile.)

Most pilots do this, or lean to 50 RPM rich of peak to keep EGT down. Many pilots do not lean at all until 5000 feet. I have an EGT guage and the temp does rise a small amount when leaned as I do.

The mechanic says that leaning at all at these altitudes will ruin the engine. This directly contradicts the POH.

I am very familiar with the damage that can be caused by running TOO lean for TOO long, however, if I am running richer than the POH says is proper, I am confused by the mechanics statement that I may be ruining the engine.

I would like to hear from anyone who could spread some light on this subject for me.

Thax,
Mark Lieberman 74040,1537@compuserv.com