And when bot the engine and airframe manufacturer contradict them selves and
each other what then?
since the AFM generally refers one to the engine manual, for matters such as leaning...I'd generally use the engine manual, if I had it...in reference to my mention of CHT/EGT...I was indirectly refering to leaning... The more instrumentation the better it can be done from primative methodes of pulling back to getting a bit of rough running the going forward..or even just putting the mixture just so...so a complex scientific analyis sunject to endless hangar talk...of course for that I just follow the books which ever maybe available...just as each registrations has it'sown POH so does eeach engine...of course the flight manual alone is just fine
as far as mag checks I don't make a huge deal out of them I just do them at run-up as I'm told...I'm not that smart
As far as the different run-up RPMs between the manuals- on older well worn planes the needle[s] on the tach[s] is/are jumping too much to see the RPM drop so I'd use the higher RPM to smooth things out...and since my students probably wont use the engine book I just go with the POH figures ...If I owned the plane I would use the engine manufacturer's figures...
I know just enough details about the engine to get myself in trouble...so I have to use the available manuals...I think jet engines and the PT-6 and Garrett are easier than pistons...more clear cut...but I'm not teaching rocket engineering so I just do [and have my students do] what the checklist or POH says... We don't even have access to the engine manuals Louie keep those at his house they are his planes....
That being said I agree 100% with the above post...it takes some discretion and really understanding what's what to apply the engine/POH combo judiciously...one can never go wrong with the AFM/POH