Mixture leaning question.

[RadioSaigon]

mea culpa

On re-reading my post I must confess to a poor choice of language, leading to some subsequent posters assuming the feature I speak of as taking your mixture to full rich with the throttle firewalled -not my belief (or intention) at all. Such an attribute could be potentially fatal, leading to an excessively over-rich mixture and subsequent engine shut-down. Simply stated, that was the context within which it was explained to me all those years ago when I first noticed the behaviour and set about polling other pilots and engineers for why; even though I understood clearly it did not take the mixture to full-rich, I didn't modify the language in my own mind.

Rather my intention is to highlight an attribute that dramatically enrichens the mixture with the throttle all the way forward. The evidence of this can be easily established by anyone in a 172, as outlined previously. Keep an eye on your EGT as you slide the throttle in -it'll head straight towards the bottom of the scale! Not a feature I would consider an "economiser" at all Oktas8 -quite the opposite in fact.

Were I to enrich the mixture prior to selecting climb-power, I would be looking for a drop of in the region of around 100deg, rather than the several hundred degrees drop your "ecomomiser" causes. To me, the effect is excessive and counter-productive, which IMO is very relevant to the question originally posted by Steve181 (BTW -the 181 is another aicraft that has a similar attribute, as does its stable-mate, the 161).

Far be it from me to suggest that anyone accept anything they read here as gospel AerocatS2A -I wouldn't; without supporting evidence. My posts direct people towards information not contained in their AFM (a very poor document IMO, as evidenced by my previous posts in other threads... probably best not to reignite that debate here) with the intention of at a minimum raising awareness, encouraging debate and hopefully inspiring more than a little curiousity and thoughtful knowledge-seeking. Are you up for it???

Simply throwing "read the AFM" at me or any other serious querant in here is IMO a cop-out of the worst kind. It reeks of someone that doesn't care enough to thoroughly know their aircraft. That is not a personal criticism directed at any specific individual either, rather a criticism of both the authors and publishers of those poor documents -and those that do behave as if the words written in their AFM will absolve them of all responsibility, should their actions or inactions lead to all turning to custard.

It is my belief that going to full throttle before initiating a climb in a 172 will alone more than sufficiently enrichen your mixture to counter the loss of airflow cooling within your engine. Any additional manual mixture enrichment is IMO excessive and counter-productive. My preferred method of achieving this is to manually enrich the mixture the desired amount myself, then advance the throttle to max RPM (and presumably MP) whilst keeping the throttle below any additional "automatic" enrichment.