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The reconfigurable flight control system was developed, applying a nonlinear aircraft model following control algorithm to support the autopilot. The model of a six degrees of freedom airplane with nonlinear aerodynamics and second-order dynamics of control system actuators was supplemented by aircraft autopilot based on classical control laws. The autopilot commands the aircraft in normal operations. In failure cases, the control system reconfiguration is performed using comparison of control external loads on damaged aircraft with loads in undamaged aircraft operation. Fuzzy logic method produces the control signals preventing the consequences of failures. The objective of reconfiguration is to continue the performed flight, including maneuvers, and, if this is not possible, to obtain the steady flight. The aircraft simulation model was tested for consistency with the expected flight performance. The selected autopilot functions were validated and reconfiguration applied in selected cases of failures. The final simulations proved the efficiency of reconfiguration. DOI: 10.1061/(ASCE)AS.1943-5525.0000050 CE Database subject headings: Aerospace engineering; Aircraft; Control systems; Safety. Author keywords: Aerospace engineering; Aircraft; Control systems; Transportation safety.

The main factor in design and operation of aircraft is safety of an airplane. The 'safety culture' developed in aeronautics results in detailed regulations and certification procedures in all phases of aircraft design and operation. But despite that, aircraft safety depends on several unpredictable factors, such as the hostile actions both inside and outside of the aircraft. When failures occur during the flight, the most important actions are aimed at maintaining the aircraft controllability. The aircraft control system should be fault tolerant and ensure aircraft controllability in the event of the failure of a part of the flight control system. In this paper the influence of control surface failures on autopilot operation has been investigated. The autopilot is designed for business jet airplanes and fulfills the main functions of the real autopilot system in longitudinal and lateral directions. The autopilot structure allows implementation of various methods of reconfiguration for aircraft protection. DOI: 10.1061/(ASCE)0893-1321(2009)22:1(78) CE Database subject headings: Aerospace engineering: Aircraft: Control systems; Safety.