Let’s be honest though. Having your stab program automatically at a prescribed airspeed is hardly a FBW FCS.
It's kind of FBW "lite."
It did have at least a couple other inputs though. I remember collective pitch being a big one and it would move a lot for that (especially when you entered an auto). Sideslip was another one (basically anything that affects the airflow on the stab, either from the rotor wash or from the slipstream/relative wind of the helicopter's flight path). The whole point of it was to keep the nose lower during dynamic maneuvering so you could see out front better—especially during an aggressive approach into an LZ—at least compared to conventional fixed stabs like the upside-down wing on the Huey. Overall I thought it was kind of a Rube Goldberg thing that did a better job than a fixed stab and it was an admirable engineering attempt to make the helicopter better at its mission, but I didn't think it wasn't worth the cost in spare parts, maintenance, and dispatch (no Huey or 53 ever scrubbed a mission for a stab amp, but at least for the Navy 60 that was a downer).
I will say that once they ironed out the bugs, Sikorsky got the common failure mode right by designing a very simple, obvious safeguard- i.e. if there's a fault then the system freezes in place and reverts to manual slew only. And in comparison, Boeing overlooked that obvious safeguard (and a few others) on their MCAS. It started as a really neat idea to use new technology to make the big airplane fly better and feel more like the little airplane from 50 years ago. They've successfully used something similar on one or two other types and it's a similar concept to the Sikorsky automatic stabilator (new tech to make the aircraft fly better, particularly in pitch feel). But they engineered their system with an unintentional
but entirely foreseeable failure mode that let it run away, uncontrolled. Now, this isn't the whole story because you could always override a runaway MCAS by doing some very simple pilot 101 stuff (trimming the airplane... something the ET302 first officer utterly failed to do, and for whatever reason most of the aviation press doesn't hammer that point nearly as much as they should, but that's another discussion).
Anyway, as
@Pags alluded about the "devil you know," everything on an aircraft is some tradeoff or another, and between the drawing board and when the system has been in service for ten or twenty years, sometimes it works out great and sometimes it's not pretty at all.
That's a complicated way of saying what I meant to say.
