FAR 29.695 requires single fault tolerance capability for flight critical boosted control systems such as hydraulic actuators used for rotor blade pitch. Single fault tolerance would mean having two independent actuation systems capable of performing the same function, where in the event one experiences loss of function for any (credible) failure mode, the other will be capable of continuing to perform the function as required for safe flight. This means every half of a single fault tolerant system must be able to operate independent of the other half, from end to end.
Having functional redundancy in just part of a system is helpful, but does not usually meet full system functional fault tolerance requirements.