This paper provides finite time estimation of wind turbine actuator faults and unknown aerodynamic load. Furthermore, finite-time state estimation of drivetrain, generator, and pitch subsystems are addressed in the contrary of asymptotic state/fault estimation in previous works. A realistic wind turbine model, incorporating the aero-elastic FAST simulator, is considered as the simulation example. Generally, aerodynamic load is not measurable in real applications due to instrument limitations, then, it is considered as an unknown input in this study. A novel terminal sliding mode observer is introduced for finite-time estimation of generator/convertor states, faults, and unknown aerodynamic load. Pitch actuator hydraulic pressure drop is modelled as an additive fault, by introducing a fault indicator. Then, two cascaded sliding mode observers are exploited for each pitch subsystem, to provide finite time state and fault reconstructions. Sufficient number of design parameters helps to achieve desired accuracy and convergence time. Finally, simulation results authenticate finite time estimation of wind turbine states and simultaneous actuator faults. (C) 2018 Elsevier Ltd. All rights reserved.