SAS and VP.
TRE makes sense if during auto/eol you want to turn, say 180 degrees into wind. Without TRE you have to rely on side slip to get it round the corner and we all know that takes time and height. With TRE at hand you simply apply pedal during the turn to hasten the change in direction. You may want to dodge obstacles during auto, how do you do that comfortably during auto with no TR? It could be achieved but at the expense of a marked increase in height loss.
At the bottom of an auto/eol when you flare, the Nr goes up...so what would happen to the nose of the a/c if you didnt have a TR? It would put you in a yaw offset situation which would probably make it harder to cross control to land.
All in all it still strikes me as odd that designs like this exist when the other far simpler designs don't rely on the engine having to be kept running if the hi spd shaft fails.
PS: The designers obviously beleive there is a need to drive the TR when a hi spd shaft fails because they advise you to keep the engine running during this malfunction. So presumably my argument that you always need a TR running to assist flight is true?
[Yes - I know a/c survive without TR's, we've seen examples recently. But from a design perspective, AS350's and some others have designed in the need to keep your FPT running during a hi spd shaft failure????
C'mon u 2 ...you can do better