My bad, should have said A320 onwards. Airbus had to massively improve its “Mean Time Between Failures” with FBW even the way the pipes were joined was revolutionised (Permaswage joints rather than nut and union). During manufacture we proof pressure tested all Airbus hydraulic systems to 5,200 PSIG and only once in ten years had a leak ( which coincidentally was what A of G has had in service) Looking at the experienced posters above can we agree an A320 and subs a single system is unlikely to fail more than once every ten years)?