Abstract: An aircraft includes an overpressure valve with a sealing member which is moveable, in response to a first pressure differential across the valve, between a closed position and an open position. The overpressure valve further has a frangible portion, for example, a carbon or sheet metal disc. The frangible portion is arranged to fail in response to a second pressure differential across the valve, the second pressure differential being more than the first pressure differential. Thus the valve is still able to relieve pressure when the sealing member is jammed (due to ice, for example). The valve may be in the surge tank of a fuel tank system.

Abstract: An aircraft venting tank (for example a surge tank) has a stack pipe unit. The stack pipe unit comprises first and second portions and houses a frangible overpressure protector element (for example a frangible disc). The stack pipe unit may be arranged to have a fitted configuration in which the first portion of the stack pipe unit is attached to a part of the venting tank structure, the first portion is coupled to the second portion, and the second portion is coupled to another part of the venting tank structure. The first portion may be held in a relationship with the second portion so as to form a seal between the frangible element, and the first and second portions. In a frangible element-replacement configuration the second portion may be coupled to the venting tank structure, such that the frangible overpressure protector element can be replaced without removal of the second portion from the venting tank structure.

Abstract: An aircraft fuel tank assembly comprises a first fuel tank, a second fuel tank and a tank-to-tank overpressure protector therebetween. The overpressure protector has a closed state and an open state. The fuel tank assembly further comprises an indicator for indicating whether the overpressure protector is in the open or closed state, the indication of the indicator being able to be sensed at a location outside of the fuel tanks. The fuel tank assembly may comprise a test mechanism arranged to effect movement of the overpressure valve from the closed state to the open state, the test mechanism being operable from a location outside a fuel tank. The fuel tank assembly may comprise an overpressure valve re-set mechanism, the re-set mechanism being operable from a location outside the fuel tanks.

Abstract: An aircraft venting tank (for example a surge tank) has a stack pipe unit. The stack pipe unit comprises first and second portions and houses a frangible overpressure protector element (for example a frangible disc). The stack pipe unit may be arranged to have a fitted configuration in which the first portion of the stack pipe unit is attached to a part of the venting tank structure, the first portion is coupled to the second portion, and the second portion is coupled to another part of the venting tank structure. The first portion may be held in a relationship with the second portion so as to form a seal between the frangible element, and the first and second portions. In a frangible element-replacement configuration the second portion may be coupled to the venting tank structure, such that the frangible overpressure protector element can be replaced without removal of the second portion from the venting tank structure.

Abstract: An aircraft fuel tank assembly comprises a first fuel tank, a second fuel tank and a tank-to-tank overpressure protector therebetween. The overpressure protector has a closed state and an open state. The fuel tank assembly further comprises an indicator for indicating whether the overpressure protector is in the open or closed state, the indication of the indicator being able to be sensed at a location outside of the fuel tanks. The fuel tank assembly may comprise a test mechanism arranged to effect movement of the overpressure valve from the closed state to the open state, the test mechanism being operable from a location outside a fuel tank. The fuel tank assembly may comprise an overpressure valve re-set mechanism, the re-set mechanism being operable from a location outside the fuel tanks.

Abstract: An aircraft comprises an overpressure valve, the overpressure valve comprising a sealing member which is moveable, in response to a first pressure differential across the valve, between a closed position and an open position. The overpressure valve further comprises a frangible portion, for example a carbon or sheet metal disc. The frangible portion is arranged to fail in response to a second pressure differential across the valve, the second pressure differential being more than the first pressure differential. Thus the valve is still able to relieve pressure when the sealing member is jammed (due to ice for example). It is therefore relatively safe. The valve may be in the surge tank of a fuel tank system.