Any aircraft rudder is subject to considerable forces that determine its position via a force or torque balance equation . In extreme cases these forces can lead to loss of rudder control or even destruction of the rudder , as on American Airlines Flight 587 ( the same principles also apply to water vessels , of course , but it is more important for aircraft because they have lower engineering margins ) . Maximum rudder deflection is controlled by a rudder travel limiter . The largest achievable angle of a rudder in flight is called its '' ' blowdown limit ' '' ; it is achieved when the force from the air or blowdown equals the maximum available hydraulic pressure
American Airlines Flight 587
American Airlines Flight 587
Rudder