Abstract: A power conversion circuitry configured to detect an electrical fault, and methods of detecting an electrical fault in power conversion circuitry, the power conversion circuitry including: switching circuitry configured to control a current flowing along a current path between first and second nodes of the power conversion circuitry; a current sensor connected to the current path, the current sensor configured to measure a rate of change of the current flowing along the current path; and control circuitry connected to the current sensor and the switching circuitry, the control circuitry configured to: detect an electrical fault if a rate of change of the current measured by the current sensor exceeds a fault threshold, and configure the switching circuitry to adjust current flow in the power conversion circuitry when an electrical fault is detected.

Abstract: A power conversion circuitry configured to transition between modes of operation during an electrical fault, including: switching circuitry configured to control currents flowing along a plurality of current paths between respective pairs of nodes, wherein the paths include first and second transistor-diode pairs; and control circuitry connected to the switching circuitry configured to: configure the switching circuitry to transition, when an electrical fault is detected, to a first mode of operation by configuring the transistors to switch to a non-conducting state so currents flow through the diodes, determine when current begins to flow through a diode, and configure the switching circuitry to transition from the first mode to a fault mode of operation by configuring the transistors to sequentially switch to a conducting state so currents flow through the configured transistors. Also, a method of controlling power conversion circuitry to transition between modes of operation during an electrical fault.

Abstract: Gearboxes for aircraft gas turbine engines, in particular arrangements for journal bearings such gearboxes, and related methods of operating such gearboxes and gas turbine engines. A gearbox for an aircraft gas turbine engine includes: a sun gear; a plurality of planet gears surrounding and engaged with the sun gear; and a ring gear surrounding and engaged with the plurality of planet gears, each of the plurality of planet gears being rotatably mounted around a pin of a planet gear carrier with a journal bearing having an internal sliding surface on the planet gear and an external sliding surface on the pin.

Abstract: A method of evaluating a composite sample comprises providing a flatbed scanner comprising a scanning head movable along a scanning direction; providing a composite sample comprising a plurality of plies arranged on planes parallel to a longitudinal direction and comprising a scanning plane containing ply edges, wherein the ply edges are oriented parallel to the longitudinal direction; arranging the composite sample on the flatbed scanner such that the scanning plane is parallel to the scanning direction and the ply edges of the scanning plane are perpendicular to the scanning direction; moving the scanning head along the scanning direction and perpendicularly to the ply edges to scan the scanning plane of the composite sample and obtain an image of the scanning plane; and evaluating the image to identify possible defects in the composite sample.

Abstract: A joint assembly joins first and second components about a common axis. The first component has a first end portion having a radially outwardly facing surface shaped to fit radially inside a second surface of a hollow second end portion of the second component to form an interface between the opposing first and second surfaces. The first and second surfaces have a concavity extending laterally with respect to the axis such that when the first and second surfaces are opposingly arranged the opposing concavities define a cavity at the interface. A retaining member is insertable into the cavity at the interface to prevent axial separation of the first and second components. One of the first and second end portions has a free end protrusion axially spaced from the concavity and the other of the first and second end portions has an axially extending recess arranged to receive the free end.

Abstract: A gas turbine engine includes a core engine casing, a bypass duct and a core engine duct. The gas turbine engine further includes a plurality of flaps pivotally coupled to the core engine casing and arranged circumferentially around a principal rotational axis. Each flap extends from a first casing end and is configured to pivotally rotate relative to core engine casing about a pivot axis between a first position and a second position. In the first position, each flap is disposed in a circumferential direction and is radially disposed between a plurality of outlet guide vanes and a plurality of stator vanes. In the second position, each flap is inclined to the first position and extends at least partially into the bypass duct and the core engine duct.

Abstract: A gas turbine engine system includes a hydrogen-burning gas turbine engine and a fuel system including a fuel line arranged to receive gaseous hydrogen at an input thereof and provide the gaseous hydrogen to combustion apparatus of the hydrogen-burning gas turbine engine and a vent line including a vent valve and having a first end coupled to the fuel line and a second end disposed remotely from the hydrogen-burning gas turbine engine. A controller is arranged to switch the vent valve from a closed state to an open state upon detection of an engine shaft-break or similar condition, thus providing rapid evacuation of gaseous hydrogen from the fuel line and hence rapid shut-down of the engine. The engine may be shut down more rapidly than is possible by means of a shut-off valve within the fuel line.

Abstract: A gas turbine engine includes a core engine casing, a bypass duct and a core engine duct. The gas turbine engine further includes a plurality of flaps pivotally coupled to the core engine casing and arranged circumferentially around a principal rotational axis. Each flap extends from a first casing end and is configured to pivotally rotate relative to core engine casing about a pivot axis between a first position and a second position. In the first position, each flap is disposed in a circumferential direction and is radially disposed between a plurality of outlet guide vanes and a plurality of stator vanes. In the second position, each flap is inclined to the first position and extends at least partially into the bypass duct and the core engine duct.

Abstract: A repair system for in-situ repair of a machine. The repair system includes a laser unit configured to emit a laser beam, a galvanometer optically coupled to the laser unit and configured to adjust the laser beam received from the laser unit, a source of a flexible metallic mesh, a delivery unit configured to receive the flexible metallic mesh from the source of the flexible metallic mesh, and a controller communicably coupled to the laser unit, the galvanometer, and the delivery unit. The controller is configured to control the delivery unit to deposit the flexible metallic mesh on a surface of the machine. The controller is further configured to control the laser unit to emit the laser beam and to control the galvanometer to adjust the laser beam in order to weld the flexible metallic mesh to the surface of the machine, thereby forming a repair patch.

Abstract: A computer implemented method of modelling the degradation of at least a component within an abrasive environment, the method comprising: obtaining a 3D scan of a surface of a component, processing the surface images of the component, determining the surface properties, inputting the data into a trained prediction model, predicting the performance of the component, and simulating the surface evolution over time or use of the component.

Abstract: A method for facilitating maintenance management of a propulsion system, such as an engine, for a vehicle is disclosed. The method comprises obtaining, for each of a plurality of propulsion systems, records of maintenance events experienced by the propulsion system, and records of traversals of transport routes by the propulsion system during a period of propulsion system operation. The method further comprises using a Machine Learning model to classify the recorded maintenance events into a plurality of maintenance categories. The method then comprises identifying, from the classified recorded maintenance events and the records of traversals of transport routes, a correlation between a given maintenance category and the transport routes traversed by propulsion systems during operational periods preceding maintenance events classified into the maintenance category. The correlation may be used in maintenance and/or route planning for propulsion systems.

Abstract: A laser ablation tool comprising a laser source which produces a beam heaving a beam path and an ablation head, the ablation head comprising a housing which on each side of the beam path is separated into a first and second portion, and at least a first Risley prism and a second Risley prism connected to the first and second portions of the housing the first and second Risley prisms being connected to a rotation mechanism, so that the two Risley prisms can be moved relative to each other and the housing so as to deflect the beam.

Abstract: A laser ablation tool including, a pulsed laser source, a prism that rotates in a plane perpendicular to light from the laser source, and a mirror that is moveable in at least one direction and which is set at an angle relative to the light from the laser source.

Abstract: A bearing carrier support for connecting a rotary shaft of a gas turbine engine to a static portion of the gas turbine engine. The bearing carrier support has: a bearing portion for supporting the rotary shaft; a flange portion for attaching the bearing carrier support to the static portion of the gas turbine engine; and a support portion that connects the flange portion and the bearing portion. The support portion has a plurality of circumferentially distributed struts that are axially aligned with respect to the rotary shaft. The number of struts is at least 500 and the diameter of each strut is no more than 3 mm.

Abstract: Gearboxes for aircraft gas turbine engines, in particular arrangements for journal bearings such gearboxes, and related methods of operating such gearboxes and gas turbine engines, including a gearbox for an aircraft gas turbine engine, the gearbox including: a sun gear; a plurality of planet gears surrounding and engaged with the sun gear; and a ring gear surrounding and engaged with the plurality of planet gears, each of the plurality of planet gears being rotatably mounted around a pin of a planet gear carrier with a journal bearing having an internal sliding surface on the planet gear and an external sliding surface on the pin.

Abstract: A gas turbine engine for an aircraft configured with an engine core that has a turbine, a compressor, and a core shaft connecting the turbine to the compressor. A fan located upstream of the engine core, that has a plurality of fan blades. A gearbox arranged to receive an input from the core shaft and to output to the fan so as to drive the fan at a lower rotational speed than the core shaft. The gearbox being an epicyclic gearbox having a sun gear, a plurality of planet gears, a ring gear, and a planet carrier on which the planet gears are mounted. The gearbox having an overall gear mesh stiffness, and wherein the overall gear mesh stiffness of the gearbox is greater than or equal to 1.05×109 N/m and less than or equal to 8.0×109 N/m.

Abstract: A resin composition that is useful in the preparation of protective coatings. The resin composition comprises a polyfunctional cyanate ester, a phenol-end-modified PDMS oligomer, and a catalyst.

Abstract: A shaft component, which in particular can be connected or is connected to the input or output side of a gear box in a gas turbine engine, in particular an aircraft engine, wherein the shaft component has at least two regions comprising fiber reinforced plastic, with fibers in the at least two regions differing in their composition, their geometric properties, their density, their radial position, their axial position and/or in their fiber orientation in the shaft component.

Abstract: A Z-pin for increasing a delamination resistance of continuous fibre-reinforced polymer composites, formed of a composite material including a polymer matrix, and a plurality of fibres embedded in the polymer matrix and aligned along the length direction of Z-pin, the fibres having an elongation at break of at least 2% and a tensile strength of at least 5 GPa, the polymer matrix having an elongation at break equal to or greater than the elongation at break of the fibres, and a tensile strength of at least 120 MPa.

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.