So whats that number that your pile of Amflight data shows?
If I remember correctly, and it's been a few years, once we got the CHT's below 185 degree's the amount damage you'd get from going to idle was minimal. What you DON'T want to do is go from 350 degree's on your CHT's (or some high number, I don't remember the scale of the gauge anymore) to idle.
Basically what it meant is that we stage cooled until we were at about 18" of power, and then you could go to idle no problem. We had the same issues with takeoff to, BTW, we were not allowed to takeoff until we got our CHT's into a rage that would not damage the engine when you poured on the coals.
Can you, without a shadow of a doubt, say that every single Amflight pilot of a 540 powered airplane followed the company SOP to a T? Were they never in a rush to make a schedule and went balls to the wall to the marker, and then slammed the throttle to idle.
What in the world kind of a question is that? Without a shadow of a doubt? No we don't have FOQA data from the Chieftains, but I'd say that the vast majority if pilots flew within SOP. Every time I was flying with one they did, nor did they attempt to push it. We had our numbers worked out pretty well in that we didn't need to rush much of anything, we just needed to be on time, using the proper procedures. It was drilled into their heads that it might not be their engine that comes apart on them if they abuse them, but it could be their buddy on takeoff who pops a cylinder and crashes. It's happened before with PT6's.
I should add that it is my opinion that smooth power reductions are more important than slow power reductions.
It is not my opinion, but instead my study of the data and anlysis that was put in front of me that says you're wrong.
In the end, do whatever you'd like with your engine. But if you treat your engine poorly for long enough, you're going to do some damage and it'll be costly in one way or another. Either you're going to pop a cylinder or your turbo on climbout while too low to pull your chute, or worse you're going to be in a plane like a 210 where you end up without any good options while low to the ground.
Do what you like, but I've got my data and will continue to discuss it and try to dispell the myths that are out there about engines of this size.