Abstract: An apparatus for ultrasonically inspecting a component of a gas turbine engine at a centre frequency required for ultrasonic inspection of the component. The apparatus comprises an ultrasonic transducer and a waveguide. The ultrasonic transducer and the waveguide are mounted in a holder, the holder is movably mounted in a carrier, and the carrier is movably mounted in a frame. The waveguide has a first end, a second end and a surface. The waveguide is circular in cross-section, the surface of the waveguide between the first end and the second end is concave, and the waveguide reduces in diameter from the first end to the second end. The length of the waveguide is equal to or greater than 0.5 times and equal to or less than 3 times the wavelength of an ultrasonic signal at the centre frequency required for the ultrasonic inspection.

Abstract: An insert fixture for use in the manufacture of a single crystal component by a hot isostatic pressing process. The insert fixture comprising: at least a lower plate separated from an upper plate by interconnecting members. The upper plate comprises at least a slot for the insertion of the single crystal component. The lower plate features a related engagement feature for engaging with the single crystal component. The insert fixture may be cast from a ceramic material. The insert fixture may be cast from an alumina ceramic or molybdenum alloy. The interconnecting members may be made from a molybdenum alloy.

Abstract: A method of controlling a gas turbine engine includes the steps of: detecting a shaft break event in a shaft connecting a compressor of the gas turbine engine to a turbine of the gas turbine engine; and in response to this detection, activating a shaft break mitigation system which introduces a fluid into a gas flow of the gas turbine engine downstream of the turbine, or increases an amount of a fluid being provided into the gas flow of the gas turbine engine downstream of the turbine, whereby the fluid reduces an effective area of a nozzle for the gas flow so as to reduce the mass flow rate of the gas flow through the turbine.

Abstract: The present disclosure relates to a metallic shaft for connecting components of a gas turbine engine. Example embodiments include a metallic shaft (400) for connecting components of a gas turbine engine, the shaft (400) having a longitudinal axis (410) and comprising: a first section (401) extending from a first end (403) of the shaft (400) to a joint (405), the first section (401) composed of a material having a first thermal expansion coefficient along the longitudinal axis (410); a second section (402) extending from a second opposing end (404) of the shaft to the joint (405), the second section (402) composed of a material having a second thermal expansion coefficient along the longitudinal axis (410) that is different to the first thermal expansion coefficient.

Abstract: A gas turbine engine for an aircraft includes an engine core including a turbine, compressor, and core shaft connecting turbine to compressor; a fan located upstream of the engine core and including a plurality of fan blades each having a leading and trailing edge. The turbine includes a lowest pressure turbine stage having a row of rotor blades, each rotor blades extending radially and having a leading and trailing edge. The engine has a fan tip axis that joins a radially outer tip of the leading edge of a fan blade and the radially outer tip of the trailing edge of a rotor blade of the lowest pressure stage. The fan tip axis lies in a longitudinal plane which contains a centreline of engine. A fan axis angle is defined as the angle between fan tip axis and centreline, and is in a range between 10 and 20 degrees.

Abstract: A mount structure for mounting an ancillary engine unit to a gas turbine engine is provided. The mount structure has plural elongate struts which each extend from a connector portion at one end of the strut to a fastening portion at the other end of the strut. The housing of the ancillary engine unit is formed of a first material having a first coefficient of thermal expansion, and the elongate struts are formed of a second material having a second coefficient of thermal expansion. Each elongate strut extends away from its connector portion in a direction which is crosswise to the direction of the hypothetical differential thermal strain at that connector portion. The mount structure further has a containment bracket which is configured to contain each connector portion.

Abstract: A superconducting electrical power distribution system has a superconducting bus bar and one or more bus bar thermal conductor lines extending in thermal proximity along the bus bar to receive heat from the bus bar over the length of the bus bar. The system further has superconducting cables electrically connected to the bus bar at respective electrical joints distributed along the bus bar. The system further has a cryogenic cooling sub-system. The system further has a network comprising first and second thermal conductor lines, each line comprising a cold end which is cooled by the cryogenic cooling sub-system, and an opposite hot end, whereby heat received by each line is normally conducted along the line in a direction from its hot end to its cold end.

Abstract: A superconducting electrical power distribution network has a superconducting bus bar and superconducting cables electrically connected to the bus bar at respective joints distributed along the bus bar. The network further has a first coolant system for providing first cryogenic fluid and first circuits for circulating the first cryogenic fluid provided by the first coolant system. The first circuits comprise: a bus bar flow path which extends along and thereby cools the bus bar, cable flow paths which respectively extend along and thereby cool the cables, cooling junctions where the bus bar and cable flow paths meet at the electrical connection joints, inflow lines which send the first cryogenic fluid from the first coolant system to the flow paths, and outflow lines which remove the first cryogenic fluid from the flow paths.

Abstract: A method is provided for measuring and validating a dimensional feature of a component for compliance with a specification value for the feature. The method comprises the steps of: (a) measuring the dimensional feature of the component to a measurement level of accuracy using a co-ordinate measurement machine; (b) comparing the measurement level of accuracy of the measurement of the dimensional feature with a predetermined level of accuracy; (c) reformatting the measurement level of accuracy of the measurement of the dimensional feature to a level equal to the predetermined level of accuracy when the measurement level of accuracy is greater than the predetermined level of accuracy; and (d) comparing the reformatted measurement of the dimensional feature to the specification value for the dimensional feature, and validating the reformatted measurement when it is within a predetermined tolerance range for the specification value.

Abstract: A component for a fastening arrangement of a gas turbine engine, the component comprising: a first abutment member; a second abutment member; a spring member between the first and second abutment members; a conduit comprising a throughole through the first and second abutment members and the spring member; the component being configured such that a shaft of a fastener passes through the throughole, a head of the fastener abuts the first abutment member and a part to be fastened by the fastening arrangement abuts the second abutment member, when the component is in the fastening arrangement.

Abstract: A method of determining the displacement of a component within a device during operation of the device, the method comprising the steps of: obtaining a first x-ray image of the device while the device is in a first operation state; obtaining a second x-ray image of the device while the device is in a second operation state different to the first operation state; processing each of the first and the second image, wherein the processing comprises applying a filter obtained based on the noise of the image and a frequency characteristic of the image; superimposing the first and the second images to align a predetermined point in each of the first and the second images; and measuring the displacement of an edge associated with the component between the first and the second image to obtain the displacement of the component within the device during operation of the device.

Abstract: A method of classifying a stator winding fault in a brushless synchronous generator includes measuring an electrical parameter of the stator winding and classifying the fault by calculating positive or negative sequence harmonics of the parameter and comparing one or more harmonic component to a threshold.

Abstract: An electric motor generator system has a hollow rotatable shaft, a coil spar, and a plurality of magnet portions. The hollow rotatable shaft has a central longitudinal axis. The coil spar comprises one or more coil assemblies and is positioned concentrically within the hollow rotatable shaft. Each of the magnet portions is shaped to conform to a radially inwardly facing surface of the shaft. Each of the plurality of magnet portions abuts conformally against the radially inwardly facing surface of the shaft between the radially inwardly facing surface and the or each coil assembly.

Abstract: A fan for a gas turbine engine, the fan comprising a first set of fan blades, each fan blade comprising a root and an axial retention feature provided on the root at a first position, and a second set of fan blades, each fan blade comprising a root and an axial retention feature provided on the root at a second position. Relative to the respective blade on which the respective retention feature is provided, the first position is different to the second position.

Abstract: A method of designing a modified aerofoil shape, the method comprising the steps of: determining a plurality of resonant frequencies of a baseline aerofoil shape; determining that one of the resonant frequencies falls within a predetermined range of frequencies; providing a plurality of aerofoil sections defining the baseline aerofoil shape; and defining a modified aerofoil shape by displacing at least one of the plurality of aerofoil sections relative to its baseline position in the baseline aerofoil shape until one of the plurality of resonant frequencies previously falling within the range of frequencies is shifted outside the range of frequencies.

Abstract: A set of gas turbine engine components comprises N gas turbine engine components. Each gas turbine engine component has a respective flow value. A method for selecting the N gas turbine engine components includes ordering the gas turbine engine components in dependence upon their respective flow value. For each ordered group of components a maximum range is determined for the respective flow values. If this maximum range is less than a pre-determined range limit then the ordered group becomes a set. If this criteria is not met then another component is added to the group, the group is reordered by flow value and the range check is repeated with allowable groups forming selected sets and further components being added as required.

Abstract: A gas turbine engine includes an inlet duct to guide a core engine flow to a compressor and an engine section stator arranged in the inlet duct upstream of the compressor including vanes with leading edges defining a first annulus area in the inlet duct, a mid-span leading edge point of the engine section stator vanes being arranged at a first radius. The compressor includes a first rotor with a row of first blades with leading edges defining a second annulus area; a mid-span leading edge point of the compressor first blades being arranged at a second radius and an axial distance from the engine section stator vane mid-span leading edge point. The ratio of the second to the first annulus area is equal or greater than 0.75, and the ratio of a difference between the first and second radius to the axial distance is equal or greater than 0.23.

Abstract: A method of reducing a burn-on time of a composite component including a body comprising a plurality of fibres layered between a front face of the body and a rear face of the body within a matrix material, wherein the body comprises an edge face between the front face and the rear face at least partially formed by edges of the layers of fibres. The method comprising shaping an edge portion of the body in order to control a local concentration of vapours from the matrix material at the edge face of the body, the vapours having been produced during heating of the composite component and having passed between the layers of fibre of the body to the edge face.

Abstract: A method of controlling a reciprocating internal combustion engine comprising: a cylinder defining a cavity having a first end and a second end; and a piston moveable within the cavity of the cylinder between the first end and the second end, the method comprising: controlling injection of a quantity of liquid air, without fuel, into the first end of the cavity at a first time when the piston is closer to the first end than the second end to cause the piston to perform a first power stroke; and controlling injection of fuel into the first end of the cavity at a second time when the piston is closer to the first end than the second end to cause the piston to perform a second power stroke.

Abstract: A unison ring assembly for a gas turbine engine has a unison ring and a plurality of levers extending from the unison ring. Each lever has a pin at one end that inserts through a bore of a respective bush mounted in the unison ring. Each bush is formed as separate first and second parts which are mounted to their through-hole by inserting the first part into the through-hole from one side of the unison ring and the second part into the through-hole from the opposing side of the unison ring. Each part has a respective stop which prevents that part from inserting into the through-hole by more than a predetermined amount. When both parts are inserted by their predetermined amounts, their ends join together to form the bush and prevent the parts being retracted from the through-hole.