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: at least one actuating device configured to receive power from hydraulic pressure of the fuel wherein the at least one actuating device is a servo system (52a - 52n) for controlling fluid flow of an aircraft turbine engine; a second supply circuit pump configured to pump fuel from the primary circuit outlet to an actuating device, wherein the second supply circuit pump is independent from the first supply circuit pump, wherein the first and second supply circuit pumps are electric pumps; and 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 characterised by a second fuel sensor, located in the second supply circuit, for producing a second sensor signal that is a function of a sensed parameter of the second supply circuit; and a controller configured to receive a signal from the second sensor, perform a freeze condition calculation based on the second sensor signal to detect a freeze condition, wherein the controller is configured to provide a drive signal to the second supply circuit pump when a freeze condition is detected, and wherein the drive signal is sent to the second supply circuit pump until the freeze condition is no longer detected by the controller. 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: at least one actuating device configured to receive power from hydraulic pressure of the fuel wherein the at least one actuating device is a servo system (52a - 52n) for controlling fluid flow of an aircraft turbine engine; a second supply circuit pump configured to pump fuel from the primary circuit outlet to an actuating device, wherein the second supply circuit pump is independent from the first supply circuit pump, wherein the first and second supply circuit pumps are electric pumps; and 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 characterised by a second fuel sensor, located in the second supply circuit, for producing a second sensor signal that is a function of a sensed parameter of the second supply circuit; and a controller configured to receive a signal from the second sensor, perform a freeze condition calculation based on the second sensor signal to detect a freeze condition, wherein the controller is configured to provide a drive signal to the second supply circuit pump when a freeze condition is detected, and wherein the drive signal is sent to the second supply circuit pump until the freeze condition is no longer detected by the controller. at least one actuating device configured to receive power from hydraulic pressure of the fuel wherein the at least one actuating device is a servo system (52a - 52n) for controlling fluid flow of an aircraft turbine engine; a second supply circuit pump configured to pump fuel from the primary circuit outlet to an actuating device, wherein the second supply circuit pump is independent from the first supply circuit pump, wherein the first and second supply circuit pumps are electric pumps; and 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 characterised by a second fuel sensor, located in the second supply circuit, for producing a second sensor signal that is a function of a sensed parameter of the second supply circuit; and a controller configured to receive a signal from the second sensor, perform a freeze condition calculation based on the second sensor signal to detect a freeze condition, wherein the controller is configured to provide a drive signal to the second supply circuit pump when a freeze condition is detected, and wherein the drive signal is sent to the second supply circuit pump until the freeze condition is no longer detected by the controller.