Abstract: A method of laser drilling a hole comprising providing a laser source at a first side of a component to laser drill a hole through the component. A light source is positioned in the path of the laser beam at the opposite side of the component. A camera is provided at the first side of the component. The camera is positioned such that it has a line of sight view of the light source through the laser drilled hole. The laser drilled hole in the component is viewed using the light provided by the light source at the opposite side of the component. The parameters of the laser drilled hole are measured using the view of the laser drilled hole provided by the camera and a flow of gas is provided over the surface of the light source to protect the light source.

Abstract: There is disclosed an access port for a casing of a gas turbine engine and a plug for plugging the access port. The access port and plug each include first and second baulking formations which are configured to engage with one another. The first and second baulking formations are spaced from one another by a unique angular separation which allows only the correct plug to be inserted into the correct access port.

Abstract: A rotor disc having an enlarged radially outer rim defining a circumferentially-extending dovetail groove for housing the root portion of a rotor blade. The groove has a groove axis and the groove is unsymmetrical about the groove axis. For example, the dovetail groove may have a restricted radially outer opening extending to an enlarged radially inner bulb profile having a pair of axially opposed curved surfaces and the opposing curved surfaces may unsymmetrical about the groove axis.

Abstract: A lean burn combustor includes a first wall and a second wall spaced from the first annular wall. Angularly spaced axially extending coolant collection manifolds collect coolant from the space between the first and second walls. A plurality of rows of axially spaced apertures extend through the first wall to supply coolant into the space between the first and second walls and one row of aperture is positioned between each pair of adjacent manifolds. The second wall extends the full length of the combustor. The second wall has a circumferentially extending wall extending towards and contacting the first wall and the wall is spaced from the downstream end of the second wall. An annular supply manifold supplies coolant to the space between the first and second walls downstream of the circumferentially extending wall and the manifolds supply coolant to the manifold. A film of coolant is discharged from the space.

Abstract: There is disclosed a method for the production of a three-dimensional product (2) via an additive layer manufacturing process such as an electron beam manufacturing process to selectively fuse parts (17) of a powder bed (16), said parts (17) corresponding to successive cross-sections of the product (2). The method involves the use of said additive layer manufacturing process to form a tool (12) by selectively fusing additional parts (18) of the powder bed (16), said additional parts (18) corresponding to successive cross-sections of the tool (12). The method also comprises a subsequent step of manipulating the tool (12) perform a processing function on the product (2).

Abstract: Methods of cleaning internal portions of additively manufactured components are provided, together with an apparatus for carrying out the cleaning. The methods use an impacting element which is contained within the internal portion and the component is vibrated to clean material from the component and leave one or more hollow portions. Various embodiments for retaining the impacting element are set out, which preferably use a grid which allows loosened powder to fall out of the component and, optionally, be recycled for use in further manufacturing processes. The methods are described in relation to components for gas turbine engines but have wider application in relation to any additively manufactured component in which it is desired to have a hollow internal portion.

Abstract: A friction welding process includes: providing a first workpiece having a first weld surface, and a second workpiece having a second weld surface; aligning the workpieces with the weld surfaces facing each other, moving one workpiece relative to the other workpiece, and engaging the first and second weld surfaces such that the movement raises the temperature at the weld surfaces to create a weld interface; and ceasing the movement and allowing the weld interface to cool to weld the workpieces together at the interface. The first workpiece has a plurality of flash removal channels formed in and/or adjacent to the first weld surface. The channels provide pathways for ejection of material from the weld interface during welding.

Abstract: A rotor assembly includes a rotor disc and a plurality of circumferentially-spaced, radially outwardly extending rotor blades. The rotor disc has a rim and a plurality of circumferentially spaced slots provided in the rim of the rotor disc, each rotor blade having a root, the root of each rotor blade being arranged in a corresponding one of the slots in the rim of the rotor disc, and at least one of the slots having a chocking device accommodated within a space between a radially outer surface of the slot and a radially inner surface of the root of the rotor blade. The chocking device includes at least a first spring and a second spring, the first and second springs each abutting a radially inner surface of the root of the corresponding rotor blade and arranged transversely relative to a longitudinal axis of the slot.

Abstract: A nose cone assembly is provided comprising a nose cone 104, a support ring 106 on which the nose cone 104 is mounted, and an insulating layer 110 disposed between the nose cone 104 and the support ring 106, the insulating layer 110 at least partially comprising glass fibers. A composite nose cone is also provided comprising an attachment region A, in which composite fibers are oriented substantially perpendicular to an axis of rotation of the nose cone 104, and an impact region I, in which composite fibers are oriented substantially parallel to the axis of rotation of the nose cone 104. Also provided is a support ring 106 for a nose cone assembly, the support ring 106 comprising an annular main body 140 and an annular projecting attachment flange 142, the attachment flange 142 terminating in a plurality of circumferentially spaced attachment tabs 144, wherein the attachment flange 142 forms with the main body 140 a cross section having at least two C curves 160, 162.

Abstract: The present invention provides a method of detecting shaft break in a shaft system comprising a shaft coupled between two masses. The method comprises a number of steps. Firstly, to define a time-dependent rotational speed equation for the shaft in terms of system inertia for an engine transient event. Then to discretize the rotational speed equation in terms of a discrete time constant in the discrete domain. Then to recursively define the discretized equation to give a recursive equation and to solve the recursive equation to determine the discrete time constant. Then to define a threshold as a function of engine power and then to set a shaft break signal to TRUE if the discrete time constant is greater than the threshold. A shaft break detection system is also provided by the present invention.

Abstract: A repair method for repairing a component (6a) of a gas turbine engine (10). The method comprises first and second steps. The first step comprises directing an energy beam toward the component (6a) to ablate a first region (54) of material to form a gap extending through the component (6a) between a repair region (58) a base region (58) of the component, wherein subsequent to the first step the repair region (58) and base region (56) are joined by a connecting portion (60). In the second step, an energy beam is direct toward the component (6a) to ablate the repair region (58) to remove the repair region (58) from the component (6a).

Abstract: The present invention provides an apparatus for providing a balancing weight in a groove on a rotor disk in a gas turbine engine. The apparatus comprises an elongate reservoir for housing a hardenable material and an inflatable element in fluid communication with the distal end of the elongate reservoir. An actuator is provided for forcing the hardenable material from the elongate reservoir to inflate the inflatable element with hardenable material within the groove on the rotor disk. A sealing device for sealing the inflated inflatable element to form the balancing weight is also provided.

Abstract: Apparatus for damping machining vibration of an object, the apparatus including: a plurality of rigid members to be positioned around the object to be machined, the plurality of rigid members defining an interior surface and an exterior surface; at least one flexible member positioned adjacent the interior surface of the plurality of rigid members, the at least one flexible member for contacting an exterior surface of the component; and a compressor to be positioned around the plurality of rigid members and the at least one flexible member, the compressor being arranged to compress the at least one flexible member onto an exterior surface of the object.

Abstract: A pressure sensing apparatus is provided for sensing gas pressure at a pressure tapping. The apparatus has a pressure sensor which provides a pressure measurement signal in response to the pressure of a gas admitted into the sensor at a gas inlet port thereof. The apparatus further has a gas conduit which extends from the inlet port. An end of the conduit distal from the inlet port is adapted to receive the gas at the pressure tapping. The apparatus further has a condenser on the gas conduit. The condenser contains condensation surfaces on which humidity in the gas flowing from the pressure tapping to the inlet port condenses out. In operation the temperature at the condenser is lower than at the pressure tapping.

Abstract: A method to detect shaft break includes monitoring first and second parameters and defining a two-dimensional parameter space that is a function of the first and second parameters, the two-dimensional parameter space includes integration regions. The method also includes defining an integration function for each integration region. For measured values of the first and second parameters, the method determines the applicable integration region and applies the integration function to the first parameter to give an integration result; and then sets a shaft break signal to TRUE when the integration result exceeds a predetermined threshold. The present invention also provides a shaft break detection system.

Abstract: Apparatus to enable rotation of a compressor, the apparatus comprising: a guide for insertion through a fan of a gas turbine engine to the compressor, the guide including: a surface arranged to guide a drive assembly through an interior portion of the gas turbine engine to the compressor; and a first fastener arranged to fasten the guide to the gas turbine engine.

Abstract: The invention concerns the damping of torsional oscillations/vibrations, particularly during electrical power generation within a gas turbine such as a civil aviation engine. The method of the invention relies on actively generating compensating oscillations in a driveline of a system to actively damp undesirable oscillations existing in the system.

Abstract: A method of open-switch fault detection in a two-level voltage source power converter comprises the steps of: i. acquiring the waveforms of three-phase alternating current of the two-level voltage source power converter; ii. calculating at least a first time derivative of each acquired waveform; and iii. using the at least first time derivatives to determine whether an open-switch fault is present in the two-level voltage source power converter.

Abstract: A method of detecting a stator fault in a multi-phase current induction machine including the steps of: obtaining a respective frequency spectrum for each of the current phases in the induction machine; deriving, from each frequency spectrum, a value for the ITHD (Inverse current Total Harmonic Distortion) for the respective current phase; calculating an ITHD deviation value corresponding to the maximum deviation for the derived ITHD values; judging whether the calculated ITHD deviation value differs from a reference deviation value; and determining, in response to a positive judgement, that there is a stator fault.

Abstract: The invention concerns an aircraft propulsion control system for an aircraft with a plurality of gas turbine engines mounted at different spaced positions relative to an airframe. One or more sensor is arranged to sense a condition indicative of vapor trail formation by an exhaust flow from one or more of the plurality of engines. A controller is arranged to be responsive to thrust demand for the aircraft and selectively to control each of the engines so as to modify the exhaust flow of at least one engine relative to at least one further engine according to the positions of the engines on the airframe. The proximity of an engine to a vortical wake flow created by the airframe may be used to determine suitable exhaust flow modifications. The controller may output a separate throttle control signal to each engine and/or may adjust the fuel composition supplied to each engine.