A method for monitoring the health of propellers in an aircraft is provided. The method includes receiving a first propeller pitch angle of a first propeller of an aircraft; calculating a first residual pitch angle which is the difference between the first propeller pitch angle and a second propeller pitch angle; and comparing the first residual pitch angle to at least one threshold. The at least one threshold may include upper and lower thresholds. It is established that the health of the propeller may be impaired if the residual pitch angle is outside the at least one threshold, for example it exceeds the upper threshold or is below the lower threshold. If it is established that the health of the propeller may be impaired, an alert is made for inspection and maintenance to take place.