Patent ID: 8496021

Claim:
An aircraft comprising: a wing; a fuel tank system, at least a part of the fuel tank system being located in the wing; and an overpressure valve associated with the fuel tank system, the overpressure valve comprising: a shaft and a sealing member attached to one end of the shaft, the sealing member being moveable between a closed position for preventing free communication of fluid through the overpressure valve and an open position for allowing free communication of fluid through the overpressure valve, the sealing member being configured to move when a pressure differential across the valve is greater than a first pressure differential in a positive direction and when the pressure differential across the valve is greater than a second pressure differential in a negative direction; and a web of frangible material extending radially outward of the shaft across at least part of the sealing member, the web of frangible material being arranged to fail when the pressure differential reaches a first increased pressure differential in the positive direction greater than the first pressure differential and when the pressure differential reaches a second increased pressure differential in the negative direction greater than the second pressure differential, and the web of frangible material being positioned for allowing free communication of fluid through the overpressure valve when the web of frangible material fails.