If mixture and engine management are parts that are wrong, what other BS is there that is also wrong. However we have no say in what is taut, CASA, the Sylabus, the CFI, the ops manual all dictate..tho shalt teach as is written in the book.
One of the chronic problems is that the regulator insists on recruiting ‘experts’ from the industry who then proceed to perpetuate the OWTs (folklore) they were taught, unhindered and untroubled by what the data actually show and the rules actually mean.
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Reforming’ the rules and administering them is merely an opportunity for these ‘experts’ to embed the folklore more deeply.
If some expert has decided that any and all cylinder damage is caused by ‘excessive leaning’, every example of cylinder damage ‘proves’ it. That ‘expert’ will of course passionately champion the cause of outlawing of ‘excessive leaning’.
Remember the good ol’ days of stomach ulcers? They were ‘caused’ by ‘spicy food’ and ‘stress’. It was ‘proved’ because every time a doctor asked someone with an ulcer: “Are you under a lot of stress or do you eat spicy foods?”, the answer was
always: “Yes, as a matter fact I am. How did you know?”. And, if the person relaxed and stopped eating spicy foods the symptoms of stomach ulcer went away. That ‘proved’ the cause.
But then someone did some proper research and proper testing and found out that, in fact, stomach ulcers are usually caused by an infection with a bacterium called H. pylori. Treat the infection by killing the bacterium and – surprise, surprise – the patient could eat spicy food and endure ‘stress’, which actually meant ‘live normally’.
Almost all piston aero engines come off the production or overhaul line with an ‘ulcer’. The ulcer is an induction/fuel system that results in each cylinder reaching peak EGT at different points on the lean curve. The symptoms of this ulcer are ‘rough running’ and ‘lean misfire’ when the mixture is leaned.
One way to ‘treat’ the ulcer is to deal with the symptoms. Keep the mixture very rich – that is, avoid the lean mixture ‘spicy foods’ and ‘stress’ that ‘cause’ the ‘rough running’ and ‘lean misfire’.
However, the
best way to ‘treat’ the ulcer is to deal with the
cause: Fix the induction and fuel system so that each cylinder reaches peak EGT at around the same point on the lean curve. Then – surprise, surprise – the engine can then eat spicy food and endure ‘stress’ – which actually means “operate normally”.