Cable systems...redundant? - Flight Controls V

I came across an article the other day that highlighted just why control cable systems are so critical to flight safety. While it will be incorrect for me to quote what the article stated, I can give a general idea about it’s key contents. First, today, I’ll give you a brief idea about the state of the art technology called fly-by-wire; and a comparison with cable systems.
In the age of fly-by-wire, cable systems are fast becoming redundant. In a fly-by-wire system, a cable is basically substituted with electrical signals. In effect the job of a cable system is accomplished electronically using systems that measure the extent (and rate) of control input by the pilot in the cockpit, which is then translated into the actual control surface movement via electrical servo motors/valves and hydraulic pressure. The nagging thought of “well, how does the pilot get the ‘feel’ of the controls” is also resolved via an artificial feel system that takes it’s inputs from the Air Data computer to sense the speed at which the aircraft is traveling amongst other external factors (such as air temperature, density and pressure).
In a cable system, the cables (assisted by other components such as pulleys and turnbuckles and bell cranks) carry the mechanical input from the pilot in the cockpit to the control surface (elevator and rudder on the tail plane and ailerons on the wings). In fly-by-wire, these inputs are ‘transported’ via electrical wires. They connect to servo motors at the control surface. The servo motor determines the extent and rate of movement desired by the pilot, and transmit this to a set of valves also within the servo motor (Technically these valves are called kinetic valves). These valves basically function to direct hydraulic pressure (by opening and closing pressure and return ports in the hydraulic pressure system) to the appropriate site of the hydraulic actuator. The actuator is a simple piston inside a cylinder, with the piston end connected to the control surface via linkage/mechanical rods to ‘actuate’ the surfaces in the desired direction, to the desired extent, at the desired rate!
Now that doesn’t sound simple, and it isn’t. But one thing you would probably understand is that there are lots of things that can easily go wrong. Luckily, advanced systems also come with advanced backups built into the system, to prevent malfunction. They don’t, however, eliminate the ‘human’ touch. And where there’s a human touch, there’s bound to be a human error! This is what we shall talk about in our next write up.