leaning a PA-38
I'm currently flying a PA-38 and had a chat to an instructor about leaning the engine in the cruise. His advice was that once in S&L flight I should gradually lean the engine until RPM peaks then continue until about 50rpm lean of peak.
I tried doing this for the first time today when settled at 3,000ft. Unfortunately as I leaned the mix the rpm didn't change at all until the mixture lever was about 1/3 of the way back. Then the engine suddenly started running rough - richening the mix a little sorted this out.
To be on the safe side I flew the rest of the flight with a full rich mixture. I obviously don't want to end up with a knackered engine but woudl like to lean effectively since I often do 2 hour legs at 3-5,000 ft.
Suggestins greatfully received!