a method for generating hydraulic power in an aircraft , the aircraft having a drive system comprising at least one transmission shaft connected to a power control unit , the power control unit having an electric motor and a hydraulic displacement machine connected to a differential gear unit for driving a common output shaft . the method includes switching the hydraulic displacement machine into a pump mode , arresting the output shaft , rotating the electric motor such that the hydraulic displacement machine is driven due to the arrested output shaft and supplying the fluid flow into a hydraulic system . a drive system of an aircraft may thereby be used for either moving control surfaces or for generating hydraulic power in an aircraft . this hydraulic power may be used to cover hydraulic load peaks during aircraft operation or to power hydraulic devices without the need of additional hydraulic power generation components .