In this study, by use of adaptive technique, a new method for fault detection and isolation is investigated. In the proposed method, estimation of fault signal obtains that it provides significant information about fault characteristics including size and severity of the fault, which are essential for many applications. The proposed technique is examined on a model of an aircraft and reconstructed fault signal is obtained. The simulation results are compared with the results achieved by use of sliding mode technique. Simulation results and comparison illustrate the capability of the proposed method.