[VBprogrammer]

Technically I'd say they introduced MCAS to increase the control force in certain scenarios (high power high angle of attack). But yes I mostly agree with you.

One thing I'm not sure about is whether Airbus would have to demonstrate proper controllability (i.e. adherence to control force regulations) in all phases of flight and corner conditions.

You could have a scenario where by they have a complete control reversal on the approach to stall but under normal law the pilot would be oblivious. This would obviously show up in direct law.

[ethbro]

I'm tracking what you're saying now.

I'd hope they would have to demonstrate both things: (1) that a given mode can or cannot be active in a certain scenario, and (2) how the plane behaves in all tested scenarios under all modes potentially active.

Is there a reason this necessarily wouldn't be the case?

[VBprogrammer]

My guess is that it's considered so unlikely that they wouldn't be required to demonstrate the full range of behaviour. In the same way as I wouldn't expect them to demonstrate all of the edge cases of the flight envelope with a failed yaw dampener. I could well be wrong though, I haven't found any good references.