@ericferret
As for the S76 servo failures as far as I can see they have not been the result of design error but of manufacture or repair failings.
The type certification design requirement is very straightforward. The manufacturer and all the authorities have had a very good knowledge of this issue for a long time. The issue is the money versus accepted loss rate. The industry has a good knowledge how to design the true fail safe Servo Actuator, ensuring the continued safe flight in any kind of single defect or a single failure.
The certification requirements are:
§ 29.695 Power boost and power-operated control system.
(a) If a power boost or power-operated control system is used, an alternate system must be immediately available that allows continued safe flight and landing in the event of:
(1) Any single failure in the power portion of the system; or
(2) The failure of all engines.
(b) Each alternate system may be a duplicate power portion or a manually operated mechanical system. The power portion includes the power source (such as hydraulic pumps), and such items as valves, lines, and actuators.
(c) The failure of mechanical parts (such as piston rods and links), and the jamming of power cylinders, must be considered unless they are extremely improbable.