A method for detecting a rotor blade pitch angle adjustment fault of a rotor blade of a wind turbine is provided, the method includes measuring a rotor blade pitch angle speed; predicting, based on an actual rotor speed, a rotor blade pitch angle speed; indicating a fault, if a first criterion is satisfied, wherein the first criterion is satisfied, if deviation between the measured rotor blade pitch angle speed and the predicted rotor blade pitch angle speed exceeds a speed threshold.