Is the statement true or false? Large or abrupt rudder inputs in mechanical mode landing may overstress the vertical stabilizer.

The statement is true. When operating the C-17 in mechanical mode during landing, any large or abrupt rudder inputs can indeed lead to overstressing the vertical stabilizer. This is because the forces applied to the aircraft's control surfaces are magnified during critical phases of flight like landing. The vertical stabilizer has design limitations on the stresses it can handle, and sudden inputs can exceed these limits.

In mechanical mode, the control system directly links the pilot's inputs to the control surfaces without electronic enhancements that might otherwise mitigate extreme control surface movements. Therefore, pilots must exercise caution and utilize smooth, controlled inputs to maintain stability and avoid any excessive aerodynamic loads on the airframe, particularly the vertical stabilizer. This understanding helps ensure safe operation and prevents potential structural damage during landing scenarios.