Thanks 212 man, I have been looking for an explanation for this modification to the T2 series for a while. Even the test pilot forum went very quiet when I mentioned it!
Having said all that, the RRPM increase is just 3%, does it really make that much difference? I suppose ECD thinks that it does, but it sure is a complicated method and not without controversy. I think we are back to Nick's old chestnut about "percieved risk" - take your hand off the collective to press a button, just incase you have an engine failure or leave you hand the collective just incase you mess up the approach.
If the engineering could take it, would it not have been better to have increased the mass of the blades and thereby slow down the rate of RRPM decay?