Abstract: An apparatus, for example for a pitch change mechanism, includes a cylinder having a magnetic portion defining an annular array of features extending parallel to the longitudinal axis of the cylinder, the cylinder rotating in use and able to translate longitudinally. There is a sensing arrangement including a stationary magnetised core and two coils connected in series and wound around the core. In use, the cylinder rotates and current is induced in the coils. Monitoring equipment is arranged to calculate rotational speed of the cylinder from the frequency of the current and to calculate longitudinal position from the relative amplitude of the current in each coil. Also a method.

Abstract: A gas turbine engine has a signal transmission system comprising a waveguide 40 which enables the transmission of microwave radio signals between a rotor 24 and stationary receiving electronics 32 of the engine. The waveguide 40 is centered on the engine axis 9.

Abstract: An apparatus, for example for a pitch change mechanism, includes a cylinder having a magnetic portion defining an annular array of features extending parallel to the longitudinal axis of the cylinder, the cylinder rotating in use and able to translate longitudinally. There is a sensing arrangement including a stationary magnetised core and two coils connected in series and wound around the core. In use, the cylinder rotates and current is induced in the coils. Monitoring equipment is arranged to calculate rotational speed of the cylinder from the frequency of the current and to calculate longitudinal position from the relative amplitude of the current in each coil. Also a method.

Abstract: A gas turbine engine has a signal transmission system comprising a waveguide 40 which enables the transmission of microwave radio signals between a rotor 24 and stationary receiving electronics 32 of the engine. The waveguide 40 is centred on the engine axis 9.

Abstract: A control apparatus 50 for a gas turbine engine for an aircraft includes engine control means 52 forming part of an outer fuel control loop and fuel control means/overthrust protector 76 forming part of an inner fuel control loop. Overthrust protection is provided within each of the engine control means 52 and the fuel control means/overthrust protector 76, which are powered and housed separately. Thus, a failure within one of these systems could not result in overthrust and demonstrably reliable overthrust protection is provided within a single channel.

Abstract: A control apparatus 50 for a gas turbine engine for an aircraft includes engine control means 52 forming part of an outer fuel control loop and fuel control means/overthrust protector 76 forming part of an inner fuel control loop. Overthrust protection is provided within each of the engine control means 52 and the fuel control means/overthrust protector 76, which are powered and housed separately. Thus, a failure within one of these systems could not result in overthrust and demonstrably reliable overthrust protection is provided within a single channel.

Abstract: An overthrust protection system for a gas turbine in which fuel is supplied at a controlled flow rate to a combustor (4) of the gas turbine. The overthrust protection system uses a bypass valve (24) to divert fuel flow away from the combustor (4). The opening of this valve is controlled by an overthrust controller (28) to divert fuel flow in response to a detected overthrust condition of the gas turbine. Diverting some of the fuel flow in this manner brings about a reduction in the thrust, allowing the overthrust condition to be controlled without resorting to a complete shut down of the gas turbine.

Abstract: An overthrust protection system for a gas turbine in which fuel is supplied at a controlled flow rate to a combustor (4) of the gas turbine. The overthrust protection system uses a bypass valve (24) to divert fuel flow away from the combustor (4). The opening of this valve is controlled by an overthrust controller (28) to divert fuel flow in response to a detected overthrust condition of the gas turbine.