(1) A sudden displacement of the rudder control (with the airplane in unaccelerated flight with zero yaw) to the maximum deflection allowed by the control stops or by pilot strength, whichever is critical;
Slight side issue. The design requirement is from neutral to full deflection (and presumably back to neutral). It is NOT a requirement to be able to handle a left-right-left-right yawing input to full deflection each side. Some Airbus pilots found that out the hard way.
Maneuvering Speed and Broken Airplanes | Left Seat
Quote from the article:
What the Airbus crash taught us—or at least should have taught us—is that Va certification standards, and certification flight test results, protect the airplane from only a single control input in only one direction at a time. Any combination of control inputs that rotate the airplane around more than a single axis creates loads for which Va does not necessarily consider or test.
Flying slower than Va also only protects the airframe from moving a flight control – elevator, ailerons, or rudder – to its full travel in a single direction, not from stop to stop. So certification calculations and flight testing show that moving the ailerons fully and abruptly full left at a speed slower than Va, for example, will not break the airplane. But if the ailerons are suddenly moved fully back to the right without the airplane stabilizing in a steady attitude, Va offers no guarantee.