This paper describes the flight test method for studying the primary control surface stuck condition and the combination stuck of the primary control. An aircraft must show controllability and trimmability under post-failure conditions. An aircraft is successfully tested under various fault conditions. It is recognized that a control surface fault is detected by monitoring the value of the coefficients related to the control surface deviation. The control surface stuck position is determined by comparing the trim value with the reference value. To detect and isolate the fault, an analysis that employs the real-time parameter estimation method is used. If the flight control system is reconfigured using online estimates of aircraft parameters from a real-time parameter estimation scheme, the reliability increases without the addition of sensors or additional cost.