Originally Posted by
linksys
with unreliable airspeed data fed into the FBW computer, does the FBW now allows the aircraft to maneuver more than allowed?
Thus allowing the aircraft to be over stressed or over loaded.
That's why the flight control laws become degraded with gradual loss of reliable input data. Once the data coming into the FBW systems passes a certain level of unreliability, the FBW system gradually hands full authority - and responsibility - back to the crew.
So at the lowest level, in Direct Law, the flight controls can be manipulated so as to exceed the aircraft's design envelope. But the key thing is that it is then under the flight crew's control - and they will be presumed to be exercising appropriate caution with their control inputs.
The only way to defeat this arrangement is to have all the airspeed etc. data be consistently wrong coming into the FBW system. If it doesn't know there's anything wrong, then it could inadvertently cause a problem. But the same would apply to a non-FBW a/c in the same circumstances - if every piece of data is misleading, but consistent, you'll inevitably be misled.