Use of Propulsion Commands to Control Directional Stability of a Damaged Transport Aircraft

Transport aircraft are configured with a flight control yaw control system that is used to stabilize the aircraft on the commanded flight path through use of the rudder commands from feedback from yaw rate and acceleration motion sensors. Should the rudder be disabled or a portion of the vertical stabilizer be damaged, the resulting oscillatory response can make accurate control of flight path difficult, with the possibility of loss of directional control of the aircraft. This damage situation can be addressed on multi-engine transports through use of engine thrust changes that replace the rudder yaw forces with thrust forces resulting in a safer approach and landing. The objective is to identify the performance change due to rudder loss for a large transport aircraft and perform an improvement in stability using an emergency yaw control mode that commands engine thrust changes using feedback from the aircraft motion sensors. This study is a part of the NASA Integrated Resilient Aircraft Control (IRAC) Fast Response Engine Research (FastER) project with Pratt and Whitney and the NASA Glenn Research Center.