blowdown limit

blowdown limit (plural blowdown limits)

1. (aviation) The maximum deflection that a control surface is capable of reaching under given flight conditions; past this limit, the aerodynamic forces acting on the control surface exceed the maximum opposing force available from the control surface's actuators.
   • 2001 March 27, National Transportation Safety Board, “3.2 Probable Cause”, in Aircraft Accident Report: Uncontrolled Descent and Collision With Terrain, United Airlines Flight 585, Boeing 737-200, N999UA, 4 Miles South of Colorado Springs Municipal Airport, Colorado Springs, Colorado, March 3, 1991‎, archived from the original on 8 May 2022, page 139:

     The National Transportation Safety Board determines that the probable cause of the United Airlines flight 585 accident was a loss of control of the airplane resulting from the movement of the rudder surface to its blowdown limit. The rudder surface most likely deflected in a direction opposite to that commanded by the pilots as a result of a jam of the main rudder power control unit servo valve secondary slide to the servo valve housing offset from its neutral position and overtravel of the primary slide.