Abstract: Disclosed herein is a method of automatically determining an operating condition of at least part of a gas turbine engine 10 for an aircraft, the method comprising: measuring one or more gas pressure waves by a gas pressure detector 401, wherein the gas pressure detector 401 is located in the gas turbine engine 10; and automatically determining, by a computing system, an operating condition of at least part of a gas turbine engine 10 in dependence on an output signal of the gas pressure detector 401.

Abstract: Disclosed herein is a method of automatically determining an operating condition of at least part of a gas turbine engine 10 for an aircraft, the method comprising: measuring one or more gas pressure waves by a gas pressure detector 401, wherein the gas pressure detector 401 is located in the gas turbine engine 10; and automatically determining, by a computing system, an operating condition of at least part of a gas turbine engine 10 in dependence on an output signal of the gas pressure detector 401.

Abstract: Apparatus for selective delivery of pressurised gas comprises a containment wall which at least partially bounds of a volume of pressurised gas during use of the apparatus, and a valve directly coupled to an output port of the containment wall such that the containment wall and the valve retain the pressurised gas when the valve is closed. The apparatus obviates the need for a duct coupling the output port to the input of the valve, and hence reduces the number of interfaces between the output port and the input of the valve from two, as in arrangements of the prior art, to one. The apparatus presents fewer failures modes compared to the case where a duct couples the output port to the valve.

Abstract: This invention relates to a single axis solid state attitude sensor in which, the spatial orientation of a resonant rode on a resonant body is maintained in alignment with the inertial angle K8 of the resonant body.