An Airbus A320 Neo recently lost all 3 hydraulic systems at the exact same time while in cruise. They are supposed to be redundant. How come Airbus hasn't grounded the A320 Neo?
https://en.wikipedia.org/wiki/Air_India_Flight_2379
The cascade of fault warnings as recorded by the digital flight data recorder, all of which occurred within a minute,[4] involved the three multiply redundant hydraulic systems, elevator flight-controls, autopilot disconnection, an emergency exit door, and even an engine anti-ice warning.[5] The Airbus A320 has three independent hydraulic systems, coded blue, green, and yellow, such that the loss of all three is considered by experts to be virtually impossible. (Too, this aircraft make and model is the one of the most flown globally.)[6] For approximately four seconds all hydraulics control was actually lost.[7][8]