In order to achieve certification, a manufacturer would have to show an equivalent level of safety of FBW compared to pushrods. Pushrods can get jammed, disconnect at the ends or I suppose possibly fracture or be shot in half, therefore the are "quite safe" not "absolutely safe". So similarly an FBW system has to be "quite safe" to the same level, but will never be "absolutely safe". Whereas 1 pushrod achieves that level of safety, it would take several computers probably running different software, multiple power sources and connections.
As you say, there is significant weight saving in large FW, some military fixed wing are so unstable that FBW is the only realistic way to fly. Maybe for x3, tiltrotor etc with complex control mixing but its harder to see the advantages for a conventional heli.
Incidentally the heli I fly already has 7 sources of electrical power, two alternators / TRUs driven by the main gearbox, a hydraulically driven turbine generator for emergency backup, a small alternator on each engine for FADEC supply, a main battery and a standby battery. Although some of these are currently too small to run a FBW system, you get the idea that redundancy of electrical supplies is already extant in modern civil helis.
Last edited by HeliComparator; 22nd April 2013 at 19:36.