What is the maximum airspeed at which full rudder deflection should be used during a slip?

The maximum airspeed at which full rudder deflection should be used during a slip is 150 KIAS. This is important as operating within this airspeed limit allows for effective control of the aircraft without risking adverse aerodynamic effects that can occur at higher speeds.

When the aircraft is in a slip, the pilot is intentionally creating a situation where the aircraft is not aligned with the relative wind, using the rudder to create side slip and maintain altitude or align with a desired flight path. At too high of an airspeed, full rudder deflection can lead to overloading the aircraft structure or could even result in a loss of control due to adverse yaw or a decrease in effective roll authority.

Staying within the specified maximum airspeed ensures that the aircraft remains controllable and reduces the risk of exceeding design limits while performing maneuvers that require a slip. Using full rudder deflection near or beyond this limit could compromise the integrity of the aircraft and lead to potential control difficulties.