A330 hydraulic fluctuations
AME343
Ive been away along time so might have missed something..
During the Blue Hyd pressurisation you say no flight controls were operated but in fact the ailerons were, as they were lifted from the droop position.
It is common to see the HYD pressure cycling when pumps are first switched on as the accumulaters become charged, as you noted, approx 3000 down to 1700 and back, me normally with shaking of the aircraft. You mentioned this occurred within a couple of seconds, did the pressure then finally stabilise at 3000??
The AMM will guide you to keep the pump running to charge the brake system for a few minutes. As already mentioned the Airbus accumulators are a likely fault in the system and do suffer from rupturing.
If you were concerned about the pump, switch the B leak measurement valve closed, does the pressure now hold at 3000psi???
You must have an answer by now but some more food for thought..
TW