Sorry SiaA,
Didn't understand your original post. Do now though!
I would be very worried if that is becoming in any way a regular occurence!!! Never heard of anything like that. We did however have many problems with the synchrophaser on the 42's particularly. It would occasionally rapidly coarsen the blade angle on the no 2 (slaved) prop and would give transient Tq and Np fluctuations. It normally was very obviously felt through the seat of the pants and could be extremely disconcerting but was always solved by selecting the synchrophaser off. I wonder whether you guys are experiencing something similar?
If I recall correctly, the synchrophaser has authority to adjust the Np by up 2.5%, but with the slight delay in the indication we were never sure if it was exceeding this value. 2.5% Np surprisingly causes a very noticable change in trim and Tq if it occurs rapidly. My own, admittedly completely unqualified, opinion would be that if was actually a feathering pump or something like that causing your problems, the Torque would almost certainly have been excessive. At climb power, particularly in a 72 at 102% or so, an Np reduction of just 8 or 9 % (assuming 77% Np) would cause a torque of 115% or more which would require maintenance action.
I'd be very interested to see what the investigation concludes.....
CP