There is described a shaft shear event detection method. The method comprises obtaining a demodulated waveform of a shaft oscillation wave superimposed on a shaft rotational speed signal, comparing the amplitude to an amplitude threshold, detecting oscillation when the amplitude threshold is exceeded for a plurality of samples, and detecting a shaft shear when oscillation continues for a predetermined time limit.

A combination valve for a steam circuit, includes a quick-closing valve and a regulating valve. The quick-closing valve and the regulating valve are arranged in a common housing. The regulating valve is displaceable by an active drive and the quick-closing valve is passively displaceable by the steam.

A method is provided involving a turbine engine. During this method, data is received indicative of twist of a shaft of the turbine engine. The data is monitored over time to identity one or more reversal events while the turbine engine is operating, where each of the reversal events corresponds to a reversal in a value sign of the data. Shaft shear is identified in the shaft based on occurrence of N number of the reversal events.

An engine system of an aircraft includes a gas turbine engine comprising at least one spool and at least one electric machine operably coupled with the at least one spool. A controller is configured to detect if the at least one spool of the gas turbine engine is in or is approaching an overspeed condition and apply a load to the at least one spool via the at least one electric machine.

The invention provides a CO.sub.2 turbine power generation system that can be easily prevented from reaching an overspeed condition. A CO.sub.2 turbine power generation system of an embodiment includes a CO.sub.2 medium shutoff valve installed in a medium flow path between a regenerative heat exchanger and a combustor. When load rejection is to be performed, the CO.sub.2 medium shutoff valve closes to shut off the supply of the medium from the regenerative heat exchanger to the combustor.

A controller for a gas turbine wherein the gas turbine includes the compressor arranged to operate at a rotational speed n, the combustor and the fuel supply includes the first fuel supply and the second fuel supply, wherein the compressor is arranged to provide air to the combustor at a steady state air mass flow rate m.sub.ss and wherein the fuel supply is arranged to supply fuel at a fuel mass flow rate m.sub.total to the combustor. The controller is arranged to, responsive to the load change ΔL to the load L, control the fuel supply to supply a proportion Z of the fuel mass flow rate m.sub.total as a fuel mass flow rate m.sub.fuel pilot via the first fuel supply based, at least in part, on a combustor mass flow rate m.sub.t.

Aircraft power and propulsion systems and methods of operating the systems, one method includes: operating electric machines of gas turbine engines as generators to extract mechanical power from spools and generating electrical power therefrom; meeting an electrical power demand of a plurality of electrical loads connected with an electrical system by supplying the plurality of electrical loads with electrical power generated by the electric machines; determining when there is an electrical system and/or the gas turbine engine fault and an amount of electrical power generated by the power and propulsion system is reduced to a lower level; and responsive to the determination: during a time period ΔT, controlling the plurality of electrical loads reducing the electrical power demand; and during the time period ΔT, meeting at least part of the electrical power demand of the plurality of electrical loads by discharging the electrical energy storage system.

A dual trip manifold assembly (TMA) includes an isolation valve assembly having a first valve configured to receive a flow of fluid from a hydraulic system fluid supply. The first valve is configured to channel the flow of fluid to at least one hydraulic circuit. The isolation valve assembly also includes a second valve configured to receive the flow of fluid from the at least one hydraulic circuit. The second valve is further configured to channel the fluid flow to a trip header. The first valve and the second valve are synchronized to each other such that rotation of one valve causes a substantially similar rotation in the other valve.

Aircraft turbine engine (10), comprising at least one first compressor, an annular combustion chamber (70) and at least one first turbine (46), which define a first flow duct (22) for a primary flow, characterised in that it comprises, between said combustion chamber (70) and said first turbine (46), a device (55, 55′) for discharging at least part of said primary flow.

A valve control device is provided in a gas turbine having a combustor for generating combustion gas, a turbine driven by the combustion gas generated by the combustor, a flow rate regulating valve for regulating the flow rate of the fuel to be supplied to the combustor, and a pressure regulating valve disposed upstream of the flow rate regulating valve, for regulating the fuel pressure. The valve control device controls the opening degree of the valve. The valve control device includes a load decrease detection part which detects a load decrease of the gas turbine, and a pressure control part which controls the opening degree of the valve in accordance with the output of the gas turbine. The valve control device suppresses instability of the gas turbine output even when the load rapidly decreases.