Helinon,
you are correct, this is not a true compressor surge but it is the nomenclature Pratt and Whitney use when we speak with them. I guess we understand each other enough to know that this is not a true "surge".
We have no link between the two engines
Our philosophy is to trouble shoot the control sytem (bias etc) and if it continues, change out the fuel control. This usually fixes the problem and the FCU is found to be out of adjustment when we get it into our shop. I guess my question still stands, what is deemed acceptable for hunting/surging by other twin manufacturers?
I appreciate all your responses, thanks!