The paper addresses the problem of the design and the application of nonlinear filtering techniques for the fault detection and isolation of aircraft model actuators. In particular, a nonlinear geometric approach is presented for both the design of nonlinear residual generators and the implementation of particle filters. The simulation results are obtained from the application of the designed diagnosis filters to a flight simulator. The developed fault diagnosis strategies rely on the nonlinear geometric approach for critical disturbance decoupling. Thus, using aircraft simulator data in a flight condition characterised by tight--coupled longitudinal and lateral dynamics validates the proposed fault diagnosis schemes. Finally, in order to analyse and compare the performance capabilities of the developed fault diagnosis strategies, extensive simulations are performed in the presence of turbulence, measurement noise and modelling errors.