Abstract: A fan blade includes an aerofoil portion including a leading edge extending from a root to a tip and defining a blade span therebetween. A leading edge thickness is defined as a thickness of a cross-section at a given radius at a location along a camber line that is 9% of the total length of the camber line from the leading edge. For cross-sections through the aerofoil portion at radii between 50% and 70% of the blade span from a root radius, the leading edge thickness includes a first maximum value. For cross-sections through the aerofoil portion at radii greater than 70% of the blade span from the root radius, the leading edge thickness includes a second maximum value that is between 105% and 125% of the first maximum value.

Abstract: A tie for a component includes a body including an elongate portion and an arch disposed adjacent to the elongate portion. The arch includes first and second middle surfaces extending between a pair of first and second outer curved surfaces, respectively. The body defines a minimum cross-sectional plane perpendicular to a longitudinal axis and passing through the elongate portion. The body further includes a minimum tie width at the minimum cross-sectional plane along a second transverse axis. The minimum tie width is greater than each of a first minimum arch width of the first middle surface and a second minimum arch width of the second middle surface by a width factor greater than or equal to 3 to less than or equal to 10.

Abstract: A method of operating an aircraft gas turbine engine including: a core including a turbine, a compressor, a combustor to combust fuel, and a core shaft connecting the turbine to the compressor; a fan upstream of the core; a fan shaft; a bearing supporting the fan shaft; an oil loop system supplying oil to the bearing; and a heat exchange system including: an air-oil heat exchanger through which oil in the oil loop system flows; and a fuel-oil heat exchanger through which oil in the oil loop system and fuel flow to transfer heat between the oil and the fuel; and a bypass pipe to allow a proportion of the oil to flow past one of the air-oil and the fuel-oil heat exchanger; and a bypass valve to allow the proportion of the oil sent through the bypass pipe to be varied.

Abstract: A gas turbine engine includes a staged combustion system having pilot fuel injectors and main fuel injectors. A fuel delivery regulator controls delivery of fuel to the pilot and main fuel injectors, receives fuel from a first fuel source containing a first fuel having a first fuel characteristic and a second fuel source containing a second fuel having a second fuel characteristic. In a transition range of operation between the pilot-only and the pilot-and-main ranges of operation, fuel is delivered to both the pilot and main fuel injectors at a transition staging ratio different from the pilot-and-main staging ratio. The fuel delivery regulator delivers fuel to one or both the pilot and main fuel injectors during the transition range of operation having a different fuel characteristic from fuel delivered to one or both the pilot and main fuel injectors during at least part of the pilot-and-main range of operation.

Abstract: An annulus filler for mounting to a rotor disc of a gas turbine engine includes a coupling portion and an outer lid. The outer lid includes a leading edge, a trailing edge, a pair of longitudinal edges, and an outer radial surface. Each longitudinal edge includes a first edge portion and a second edge portion. At least one longitudinal edge includes a recessed portion that extends at least axially between the first edge portion and the second edge portion, such that the recessed portion connects the first edge portion to the second edge portion. The recessed portion further extends circumferentially inwards from each of the first edge portion and the second edge portion towards the other longitudinal edge.

Abstract: A gas turbine engine has a compression system blade ratio defined as the ratio of the height of a fan blade to the height of the most downstream compressor blade in the range of from 45 to 95. This results in an optimum balance between installation benefits, operability, maintenance requirements and engine efficiency when the gas turbine engine is installed on an aircraft.

Abstract: A propulsion device comprises: a casing structure to surround a fan of the propulsion device; a core structure to support a core of the propulsion device; a thrust reverser unit comprising two thrust reverser halves, each thrust reverser half being pivotable about a respective hinge line between an open position for access to the core structure, and a closed position. Upper and lower support members extend from the casing structure at diametrically opposing sides of a centreline axis. For each thrust reverser half there is at least one locating arrangement comprising an upper locating arrangement with cooperating portions configured to engage each other as the thrust reverser half moves towards the closed position in a closing operation; and/or a lower locating arrangement with cooperation portions configured to engage each other as the thrust reverser half moves towards the closed position in the closing operation.

Abstract: A gas turbine engine component that has a web provided with an array of cooling holes distributed with respect to a first direction, wherein the cooling holes have a cross-sectional shape that varies along the first direction. The component may be configured so that the first direction corresponds to a loading distribution of the component which increases along the first direction from a low loading position to a high loading position.

Abstract: A gas turbine engine comprises a bypass duct and a heat exchanger assembly, the heat exchanger assembly comprising a heat exchanger and a heat exchanger duct having an inlet region, an inflection region and an outlet region. A direction of a centreline of the heat exchanger duct has a tangential component with respect to a principal rotational axis of the gas turbine engine at one or more of the inlet region, the inflection region and the outlet region. The heat exchanger is disposed within the inflection region and configured to transfer heat generated by the gas turbine engine into the flow of air as it passes through the inflection region.

Abstract: A propulsion system having an axial direction relating to a principal direction of propulsion, and a height direction perpendicular to the axial direction. The propulsion system includes a duct configured to convey a flow of fluid along the axial direction, and a heat exchanger disposed within the duct. The heat exchanger is defined between an inlet face and an outlet face and is configured to convey the flow of fluid from the inlet face to the outlet face. A heat exchanger length is defined as a minimum distance between the inlet face and the outlet face and wherein the heat exchanger length varies along the height direction such that a resistance to the flow of fluid through the heat exchanger varies along the height direction.

Abstract: A thermal management system for a gas turbine engine includes a plurality of inlet and outlet vanes extending from a bypass inner wall towards an outer cowl, a plurality of first removable shims, a plurality of second removable shims, and a third removable shim. Each first removable shim extends between and engages the outer cowl and a corresponding inlet vane. Each second removable shim extends between and engages the outer cowl and a corresponding outlet vane. The third removable shim extends between and engages a heat exchanger and the outer cowl. Each of the plurality of first removable shims, each of the plurality of second removable shims, and the third removable shim is removable for positionally adjusting the outer cowl relative to the bypass inner wall.

Abstract: A method of manufacturing a component includes forming a mould assembly including an initial mould unit, providing a seed crystal including a primary growth direction, determining an optimal angular orientation of the unit, rotating the unit to dispose the unit's optimal angular orientation, encasing the unit in a refractory material, and forming a refractory mould unit having a component mould including a mould wall defining a mould cavity, and a seed holder. In the optimal angular orientation, the seed crystal's primary growth direction is angled away from the wall, thereby forming a converging disposition with the wall in a of the wall's first region facing the central sprue and a diverging disposition with the wall in the wall's second region facing a mould heater. The method includes receiving the seed crystal within the seed holder and filling the mould cavity with molten castable material to form the component.

Abstract: A method of scanning a part comprises setting software scanning parameters of a scanning apparatus to produce an image. Setting the software scanning parameters includes setting an output voltage to a maximum output value, for example 450 kV and setting an output current and a magnification so that a power/voxel ratio of the scanning apparatus is in a range of between 2 and 3, for instance, between 2.25 and 2.75. The method further comprises scanning the part.

Abstract: A pressurised fluid duct failure event characterising method including: monitoring acoustic signals; detecting a failure event occurrence based on an acoustic signal exceeding a first failure threshold, and identifying a failure marker; estimating, for each acoustic signal, a failure detection time, based on the failure marker and a rate of change in sound pressure level for each acoustic signal; determining an acoustic weighted position for acoustic sensors; determining an estimate of a region containing the failure event as a first sub-volume of the duct based on the acoustic weighted position and a predetermined relationship between sound pressure level and regions of the duct; calculating, for each acoustic signal, one or more spectral characteristics; and determining at least one failure characteristic based on a comparison between the one or more spectral characteristics, the estimate of the region containing the failure event, and one or more predefined failure event parameters.

Abstract: A method of operating a gas turbine engine; the gas turbine engine includes a combustor. The combustor includes a combustion chamber and a plurality of fuel spray nozzles configured to inject fuel into the combustion chamber. The plurality of fuel spray nozzles includes a first subset of fuel spray nozzles and a second subset of fuel spray nozzles. The combustor is operable in a condition in which the first subset of fuel spray nozzles are supplied with more fuel than the second subset of fuel spray nozzles. A ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:2 to 1:5. The method includes: providing fuel to the one or more fuel-oil heat exchangers. Also provided is a gas turbine engine for an aircraft.

Abstract: A method comprising: receiving data from a first equipment health monitoring system, the data being for a plurality of parameters of a propulsion system; determining whether the data received from the first equipment health monitoring system includes data for a first parameter of the propulsion system; and instructing deployment of a second equipment health monitoring system to monitor the first parameter where it is determined that the data received from the first equipment health monitoring system does not include data for the first parameter.

Abstract: An aircraft includes a turbofan engine, a cabin blower system and a PEM fuel cell stack. The cabin blower system includes a cabin blower compressor arranged to be driven by mechanical power derived from a shaft of the turbofan engine. A ducting system delivers respective portions of the mass flow rate of compressed air output by the cabin blower system to a cabin space of the aircraft via an air-conditioning unit and to the cathode input of the fuel cell stack. An electric motor receives electrical power from the fuel cell stack and provides mechanical power to the compressor via a drive arrangement of the cabin blower system. Power associated with excess capacity of the cabin blower system is recovered to the cabin blower compressor, thereby mitigating or eliminating the fuel consumption penalty on the turbofan engine associated with the excess capacity.

Abstract: A pressurised fluid duct failure event location determination method including: monitoring acoustic signals; detecting a failure event occurrence based on an acoustic signal of those exceeding a first failure threshold, and identifying a failure marker; estimating, for each acoustic signal, a failure detection time; determining an acoustic weighted position for acoustic sensors based on the respective failure detection time for each acoustic signal and the position of each microphone; determining an estimate of a region containing the failure event as a first sub-volume of the duct based on the acoustic weighted position and a predetermined relationship between sound pressure level and regions of the duct; discretising the first sub-volume of the duct into a first three-dimensional grid having voxels according to a first grid mesh size; and determining a first estimate of the failure event location using a time-domain beamforming algorithm applied to the acoustic signals and the first sub-volume.

Abstract: Apparatus comprising: a propulsion system; a first equipment health monitoring system configured to generate data for a plurality of parameters of the propulsion system; a second equipment health monitoring system configured to generate data for one or more parameters of the propulsion system, at least one of the one or more parameters to be monitored by the second equipment health monitoring system being different to the plurality of parameters to be monitored by the first equipment health monitoring system.

Abstract: A gas turbine engine has a combustor with a combustion chamber and a plurality of fuel spray nozzles including a first subset of nozzles and a second subset of nozzles. The first subset of nozzles are supplied with more fuel than the second subset of nozzles. A ratio of the number of nozzles in the first subset to the number of nozzles in the second subset is in the range of 1:2 to 1:5. A method includes providing fuel to the one or more fuel-oil heat exchangers, transferring heat from oil to the fuel, and providing the fuel from the one or more fuel-oil heat exchangers to the fuel spray nozzles. Heat is transferred from the oil to the fuel to lower a viscosity of the fuel to 0.58 mm2/s or lower on injection of the fuel into the combustion chamber at cruise conditions.