In the PART position, what is adjusted for the ROLL switches on the FCS actuator panel?

In the PART (Position Adjustment/Recovery Test) mode, the ROLL switches on the Flight Control System (FCS) actuator panel adjust a ratio changer in the mechanical mode. This adjustment allows the aircraft to have greater control over roll movements. The ratio changer effectively modifies the input from the pilot's controls to enhance the response characteristics of the ailerons, ensuring that the aircraft remains stable and controllable during various flight conditions.

The operation in mechanical mode allows for a direct connection and adjustment that is necessary for fine-tuning the aircraft's handling, especially during scenarios where electronic systems might not be as reliable. This feature is crucial for achieving precise roll control, which is fundamental when performing maneuvers or during critical phases of flight, such as takeoff and landing.

The other responses pertain to aspects of the aircraft's operation but do not specifically relate to the adjustments made in the PART mode for the ROLL switches. This distinction is essential for understanding the specific functionality of adjusting the ratio changer under the PART mode and its implications for flight control.