Aircraft fuel system

A system for supplying fuel, the system comprising:

• a primary circuit for delivering fuel from a fuel tank to a primary circuit outlet;
• a first supply circuit connected to the primary circuit outlet, the first supply circuit comprising a first supply circuit pump configured to pump fuel from the primary circuit outlet to engine fuel nozzles;
• a second supply circuit also connected to the primary circuit outlet, the second supply circuit comprising:
• an actuating device configured to receive power from hydraulic pressure of the fuel;
• a second supply circuit pump configured to pump fuel from the primary circuit outlet to the actuating device, wherein the second supply circuit pump is independent from the first supply circuit pump;
• a return circuit configured to return fuel from the actuating device to the second supply circuit between the primary circuit outlet and the second supply circuit pump;
• and
• a second supply circuit fuel sensor that produces a second supply circuit sensor signal as a function of a sensed parameter of the second supply circuit;
• and
• a controller configured to perform a freeze condition calculation based on the second supply circuit sensor signal to detect a freeze condition, wherein the controller is further configured to provide a drive signal to the second supply circuit pump when the freeze condition is detected, and wherein the controller is further configured to send a drive signal to the second supply circuit pump until the freeze condition is no longer detected by the controller.