But what are the chances of both failing at the same time?? Aren't they independent systems , Each with its own pump.
Don't we fly the helicopter in case of a OEI?
Yes, we do fly the helicopter in case of a OEI; but if the remaining one fails we still have a good chance of walking away from an autorotation, unlike in a 412 that becomes un-flyable if the No2 hydraulics fail as well.
The post above by shak'n seems to prove the point: what's the reason the initial failure happened in the first place? Good airmanship as suggested by John Eacott is key.