The problem of fault estimation and accommodation of nonlinear systems with disturbances is studied u-sing adaptive observer and neural network techniques.A robust adaptive leing algorithm based on switching βs-modification is developed to realize the accurate and fast estimation of unknown actuator faults or component faults.Then a fault tolerant controller is designed to restore system performance.Dynamic error convergence and system stability can be guaranteed by Lyapunov stability theory.Finally,simulation results of quadrotor helicopter attitude systems are presented to illustrate the efficiency of the proposed techniques.