Originally Posted by
tdracer
Just curious - but is that basic (and automatic) on the A320?
I know on the 757/767 they added hydraulic generator - but that wasn't basic, it was part of the (optional) ETOPS package. They battery was supposed to be good for 30 minutes (only powering critical systems) which was basically as long as you could realistically glide after an all engine power loss. The hydraulic generator was for case where you lost main bus electrical power but the engines were still running (I don't think it could operate off the RAT, but I'm not positive). RAT hydraulic power is pretty limited...
The RAT in Airbus has to be basic. Because with engines gone both EDP driven hydraulic systems are also lost. RAT basically drives the third hydraulic system called BLUE in Airbus without which you cannot move flight controls. Blue in turn drives the emergency CSM 5kw generator which provide sufficient electrics for essential systems. If Emergency generator is lost batteries can similarly. provide DC essential and through static inverter AC essential for 30mts.