The applicable part of the original question..
Is there a benefit in having the ice vanes open during a normal takeoff/landing on a gravel strip or on a sealed runway in temperatures above freezing?
Looking through type certificate 3A20 (which includes the E90 model), ice deflectors/vanes are not mentioned.
As to their use on gravel runways, recommended generally speaking, on sealed/clean runways, closed/retracted.
Flight Safety/Simuflite etc only has their
recommendations, which are
not regulatory.
STC's were not mentioned by the original poster, so they are of no consequence to the present discussion.
Then we have...
So far as asking a FAA inspector...who has no authority to interpret regulation...
Wrong, they do it all the time, and have for many years.
Going further, and with the referenced B200, it is noted...
I am sure that the AFM for the B200 I used to fly (but do not have it to hand) specifically required the ice vanes closed for T/O as a limitation.
Yup, my manual says the same.
And finally, we have...
Some installations also use filters or additional screens prior to the engine in order to prevent compressor contamination or engine damage. This is more commonly found on aircraft which operate in an environment that is at a high risk for contamination (common on ag and firefighting aircraft, for example), but not on aircraft such as the King Air.
That is about the only reasonably correct statement
that particular poster has made so far.
All the rest from the same source is generally nonsense.
