Dan, read the whole thread and my comments in context please. RV8R99 was making snide remarks about how the Lycoming engineers should attend an APS course and how odd it was since they build em etc etc......
This is not about Lycoming engineers, rather those who write the poor materials. Usually not the same folk.
Now my reply was in defence of the position APS guys take on these matters....generally speaking, and that their position is based on the same facts and data Lycoming use, so with respect to this Service Instructions, any particular data is not relevant rather the whole concept of combustion engines, which I do not need to explain to you. You have a good enough grip on that already.
So moving to the crux of the matter, why this is another poor publication. And I say another because there have been plenty before this one. We all know it.
The thread was started by Bob, who astutely picked up on some glaring ambiguous statements.
I was also taught this wrong. Read it all but pay special attention to page 2 section B #2. I was always taught don't lean below 3K. This says if you're flying in cruise at 1000 then lean it to max RPM no exceptions.
http://www.lycoming.com/support/publ...fs/SI1497A.pdf
If taken literally this is poor advice and lacking on how to do it conservatively in order to give the best operating conditions and service life of the engine.
Did I say this was WRONG, (which is what you have asked of me), no, I said they have contradicted themselves once again, refer my first post on Page one, and I said they have not given any guidance on how to do this effectively. Especially when in the past they have been big proponents of full dirty gobby rich! To coin a phrase!
So Dan, I never said it was wrong, in some parts it is quite a revelation. It is not only trying to resolve fouling plugs, but most likely fuel systems that have been overprimed and gummed up etc etc, by subsequent starts (hot-warm) by students following the books all too literally.
You don't do this, I am almost sure do you?
So when you consider the rest of the document, of which some of the good bits are a refreshing change, the contradictory bits, and the poorly detailed procedures such as what to do if full bore at 500'....lets lean to ;
2. Cruise
Make the fuel mixture Lean to maximum RPM (all altitudes). Leaning Technique
a. Slowly make the fuel mixture Lean until the RPM decreases.
b. Make the fuel mixture Rich until the engine operates smoothly.
c. Make the fuel mixture Rich by turning the mixture knob an additional 1/2 turn (approximately 180 degrees rotation).
and with a poor F/A ratio this could be anywhere like 30-40ROP or 70-100ROP or wherever, how would you know???
Yes it is another poorly written document.
So tell us all where this SI is perfectly written and nil defects, and where the original poster, myself and others have got it wrong?
