eal401, may I suggest that you should perhaps have posed your original question with as much detail as the one above. It would also have been much more sensible to have asked your question elsewhere as this thread doesn't seem to be the place.
In a beleated attempt to answer your question, without knowing the a/c type, flight number, date or any other pertinant details, I would suggest that as the before start checklist was being actioned, perhaps the hydraulic pumps were switched on at that point and a hydraulic pipe decided that the sudden increase from 0psi to 3,000psi pressure was more than it could bear and ruptured and only then did the groundcrew inform the F/D that there was a problem.
I only suggest the above as it has happened to me in the past and only thanks to a hastily scrounged engineer from a local airline, having been given a one-off approval by our maintrol to perform a simple hydraulic pipe change, and then yours truly had the laborious task of manually pumping the contents of 20+ tins of Skydrol into the system B reservoir. All takes time and I think you'll find that 4 hours is about right.
Now, can we all calm down and stay on thread?
