Abstract: An aircraft fuel tank monitoring system is disclosure including at least one first sensor for sensing a pressure of fuel within a fuel tank; at least one second sensor for sensing a pressure of an ullage space above the fuel within the fuel tank; a processor for monitoring the change in the pressure of the fuel within the fuel tank over a time period and for monitoring the change in the pressure of the ullage space within the fuel tank over the time period, and to determine a fault if the monitored pressure changes exceed normal operating conditions.

Abstract: A system for monitoring an aircraft fluid storage tank assembly is disclosed including a pressure sensor configured to receive an acoustic signal emitted from a location within the aircraft fluid storage tank assembly in use and a controller. The controller is configured to receive information indicative of the acoustic signal from the pressure sensor and perform a determination process to determine, on the basis of the received acoustic signal, whether to output an indicator of a fault condition of the aircraft fluid storage tank assembly.

Abstract: An aircraft is disclosed including a fuel tank, and a refuelling system configured to feed fuel into the fuel tank. The refuelling system includes a sensor. The sensor is configured to measure a composition of fuel in the refuelling system before it is fed into the fuel tank, and the sensor is further configured to generate an output based on the measured composition.

Abstract: A method of controlling an inerting system of an aircraft is disclosed. The inerting system feeds inert gas into a fuel tank of the aircraft, the method includes: a) obtaining a location of the aircraft, the location comprising a current location or an expected future location; b) assessing an environmental impact of releasing of fuel vapour at the location obtained in step a); and c) controlling the inerting system based on the assessment of step b).

Abstract: A method of recovering fuel vapour from a fuel tank of an aircraft, is disclosed. The aircraft includes a fuel tank; a wing with an upper surface and a lower surface; and an opening in the lower surface of the wing. The method includes coupling an inlet of a vapour recovery system to the opening; capturing fuel vapour from the fuel tank which flows out of the opening with the inlet of the vapour recovery system; and collecting the captured fuel vapour in a vapour storage tank of the vapour recovery system.

Abstract: A fuel system for an aircraft is disclosed including a fuel tank; a valve; and a valve actuator with a control input. The valve actuator is configured to open and close the valve in response to command signals on the control input, and the opening of the valve ventilates the fuel tank. A control system is coupled to the control input and is configured to generate command signals and apply the command signals to the control input. A further aspect of the invention provides a method of ventilating a fuel system of an aircraft, the method comprising: assessing a suitability of a location of the aircraft or an environmental condition local to the aircraft for release of fuel vapour; and opening the valve on a basis of the assessment. The opening of the valve causes fuel vapour to be released from the fuel tank via the valve.