Hello all,
I ask as an ATPL ground school student so please pardon my ignorance.
Anyway, despite being able to smash out quite high scores on the question banks on hydraulic systems I do feel my knowledge on hydraulics could be better. I have one question I can't seem to find a direct answer to despite searching the web and various historic threads.
Basically, considering we have all these wonderful backup systems, 3 on Airbuses I believe at least, why is it such a big deal when we lose the main system? Why can't we just switch to the 2nd back up, if that goes, then switch to the final back up? It happens quite regularly, most recently with an Aer Lingus A333 out of Dublin, that when the main hydraulic system fails, it requires a return to base and there doesn't even seem to be enough pressure in the hydraulic system to raise the landing gear bay door, which I believe are even blown out by an accumulator (which I had in mind as being last resort for when
really hits the fan and you've nothing) ... but what about the 2 back up systems? are these not as good?
Finally, where exactly does the RAT fit in all this? From my knowledge I understand it provides basic pressure to the primary flight controls and other key systems, but why is that the first go to when there are 2 fully capable back up systems to the main one?
Thank you all for your time!