Fuel pump driven by a variable displacement motor for aerial refueling operation

A method of refueling a receiver aircraft from a tanker aircraft comprising:

• delivering fuel from a fuel pump of the tanker aircraft to the receiver aircraft at a predetermined fuel flow rate to a predetermined maximum inlet pressure at a reception coupling between the tanker aircraft and the receiver aircraft, wherein the fuel pump comprises a variable displacement motor operable to be driven by a hydraulic fluid pressure and the fuel flow rate is produced by a displacement of the variable displacement motor;
• reducing the fuel flow rate below the predetermined fuel flow rate to not exceed the predetermined maximum inlet pressure;
• and
• reducing a displacement of the variable displacement motor in response to a decrease in the hydraulic fluid pressure, wherein reducing a displacement of the variable displacement motor comprises reducing when a decrease of a hydraulic pressure reaches a threshold hydraulic pressure above a minimum hydraulic pressure.