Rob,
Do not know anything about a Thrush, curious as to how long one can be in beta on them to back up.
Limited time before ITT spike, or no issue on them?
Thanks,
John
Hi John,
Good question, and interesting thread. I really appreciate your Siai input as that is the one non revenue T-prop I could really bring myself to owning.
My neighbor owns an exquisite example.
My T-prop experience is really limited almost exclusively to ag stuff. The vast Majority in Pratts of various sizes with a smattering of Garrett and Walter stuff
as well.
It's not suprising we are looking at some of this stuff from opposite sides given your RR/Allison experience, and the differing airframes. My minimal exposure
to that engines sister in the Bell airframes tell me they are a hot start looking for a day to happen.
With regards to the Thrush and Air Tractor airframes I have experienced, virtually all of them, regardless of engine would readily take judicious use of beta
and reverse on landing. And again virtually all of them would back up as much as you could stand.They do see an initial rise in ITT (and then drop) as expected,
but I've not had one go hot on me from backing.
We do run into cooling problems with excessive ground time while hot loading in the summer, but that is a completely different issue.
Here is a good discussion that I believe touches on why we don't see that spike. You have a completely different configuration with the gear box, which probably
accounts for what you see. ;
https://aviation.stackexchange.com/...gine-keep-running-during-thrust-reversal?rq=1
I thought I read somewhere that you have a Kodiak as well. I *think* those are -34'S? You don't run in to ITT problems with that airplane in reverse do you ?
Take care, Rob