Abstract: Fuel control arrangements provide and control fuel flow to injectors through fuel control valves. The injectors are connected to respective fuel control valves which in turn are connected to a first fuel flow path. The injectors are also connected to a second fuel flow path. The fuel paths are associated with a fuel source and generally have a recirculation valve between them. When flow in the flow path is stopped, recirculation of fuel can be provided across the recirculation valve to prevent fuel degradation. By provision of a restrictor valve in the second fuel flow path control of fuel recirculation can be achieved, as well as greater flexibility by presenting fuel flow separately through the second flow path to the injector whilst the first flow path is inhibited.

Abstract: A projectile is provided for simulating multiple sequential ballistic impacts. The projectile has a plurality of relatively dense loading layers spaced along the firing direction of the projectile. Each pair of nearest-neighbour loading layers is separated by a less dense support element which maintains the spacing of the loading layers. The projectile may be suitable for simulating bird slurry impacts on stator vanes of an aero gas turbine engine.

Abstract: A gap 6 between a stationary component 2 and a rotating component 4 is sealed by means of a leaf seal comprising an array of leaves 8, 9. The leaves 8, 9 are disposed in pairs, comprising a higher curvature leaf 8 and a lower curvature leaf 9 which contact each other resiliently at their tips 12. The contact at the tips 12 provides a damping effect. As a result, the tips 12 of the leaves 8, 9 are relatively stable when subjected to an air flow F, enabling damaging flutter to be suppressed.

Abstract: A seal arrangement (1, 101) for maintaining an axial pressure differential between relative high and low pressure stages along a rotating element (2, 102), the arrangement comprising: i) a plurality of leaf or brush seal members (5) forming a circumferential seal-pack (4, 104) around the rotating element (2, 102), in-between said low and high pressure stages, for limiting leakage of fluid between said low and high pressure stages; ii) a baffle (6, 7, 106, 107) positioned on the upstream or downstream side of the seal-pack (4, 104) for regulating such leakage through the seal pack (4, 104); and iii) a control arrangement for adjusting the position of the baffle (6, 7, 106, 107) hereby to control the regulation of said leakage through the seal-pack (4, 104) and hence control the consequent blow-down effect on the seal-pack (4, 104) caused by that leakage.

Abstract: A gap 6 between a stationary component 2 and a rotating component 4 is sealed by means of a leaf seal comprising leaves 8 having a geometry such that the centre of torsion CR of the leaf 8 is disposed upstream of the centre of pressure CP at the tip 12 of the leaf 8. As a result, the tip region of the leaf 8 is relatively stable when subjected to an air flow F, enabling damaging flutter to be suppressed.

Abstract: The present invention addresses fuel supply in gas turbine engines. A splitter valve 47 is provided at a remote, benign temperature location. Injector control valves 51 are individually controlled through a fluid pressure actuation system, typically pneumatic, controlled through a solenoid bank 44 and a controller 40. Such fluid pressure actuation systems are less susceptible to high temperatures and therefore provide reliable on/off control whilst fuel demand regulation is achieved through the remote splitter valve 47.

Abstract: A method of manufacturing a milling cutter having a cutting head and a coaxial integral shank comprising the steps of grinding, in a first grinding operation, a plurality of helical flutes (5) into the outer periphery of a cutter blank from a lead end (24) using a peripheral area (16) of a first grinding wheel (15) generally of frusto-conical profile and rotatable about an axis (18) generally transversely of the milling cutter axis (1), which peripheral area (16) produces, simultaneously, the following three features: a leading face (9) of a trailing tooth; a rear face (10) on an adjacent preceding tooth; and a swarf removal gullet (13) having divergent sides, grinding, in a second grinding operation, and using a peripheral edge (19) of a second grinding wheel (20), a relief face (11), which extends rearwardly from a leading end of a tooth tip, resulting in a minimum tooth wedge angle of approximately 60°, and grinding, in a third grinding operation, a radius (23) on the end of each flute.

Abstract: A method for determining probable fail cases of a system includes the steps of: (a) receiving a pattern of input features, each feature representing measurable indicators which themselves are indicative of the condition of the system; (b) providing a set of fail cases, each fail case being represented by an expected pattern of input features, and each fail case being associated with a rule in reverse polish notation which produces a true result if the expected pattern for that rule correlates with a pattern of input features or a false result if the expected pattern for that rule does not correlate with a pattern of input features; and (c) applying the received pattern of input features to each rule to determine whether the received pattern has a true result or a false result for the respective fail case, a true result denoting a probable fail case of the system.

Abstract: A pressure rise combustor is provided with fuel provided at intermittent periods. The fuel is pulsed at timings such that the phase lag between the addition of the fuel and a resultant pressure rise is minimized. The fuel is pulsed such that the unsteady addition of heat reinforces the amplitude of an unsteady pressure fluctuation.

Abstract: A method of friction welding comprises providing a first workpiece (24) having a first weld surface (38) and a second workpiece (26) having a second weld surface (40). The first workpiece (24) is arranged such that it tapers away from the first weld surface (38), the first workpiece (24) converges in a direction away from the first weld surface (38). The first and second workpieces (24, 26) are arranged such that the first weld surface (38) abuts the second weld surface (40). The first and second workpieces (24, 26) are oscillated relative to each other such that at least one of the weld surfaces (38, 40) of at least one of the workpieces (24, 26) moves relative to the other weld surface (40, 38) of the other workpiece (26, 24) such that the temperature increases at the weld surfaces (38, 40) to create a weld interface (42). The oscillation is stopped and the first and second weld surfaces (38, 40) are allowed to cool to weld the first and second workpieces (24, 26) together.

Abstract: A control mechanism for moving at least two components of a gas turbine engine, the control mechanism comprises first and second crankshafts and a torsion bar connected to both crankshafts, each crankshaft is connected to a different component, the crankshafts engage one another via one-way abutment means and the torsion bar is pre-twisted so that up to a predetermined rotational extent the two crankshafts rotate together and beyond that extent only the first crankshaft rotates, thereby one of the two components moves more than the other component.

Abstract: A method for performing a machining operation on a part uses closed-loop control, based on feedback of information measured from the part, from the tools and machines, and from the environment, to modify the controlling parameters for the machining operation. By recording the information for all machining operations, statistical data can be generated, and the process control can be further improved by applying this statistical knowledge. Information relevant to each part can be stored, so that it can be passed on to subsequent operations in the manufacturing route.

Abstract: Cooling within aerofoils (30, 47, 67, 87) is a requirement in order that the materials from which the aerofoil (30, 47, 67, 87) is created can remain within acceptable operational parameters. Traditionally static pressure as well as enhanced dynamic pressure impingement flows have been utilised but there are problems with regard to achieving a necessary over pressure to avoid hot gas ingestion or reduced cooling effect. It will be appreciated that fluid flows and in particular coolant fluid flows must be used most appropriately in order to maintain operational efficiency. By providing a plurality of feed apertures (41, 61, 81) which are shaped to have an entry portion (51, 71, 91) which is generally elliptical and an exit portion (52, 72, 92) it is possible to grab and turn a proportion of a feed flow (44, 64, 84) for substantially perpendicular or other angular presentation to an opposed surface of a cooling chamber (42, 62, 82) within which cooling is required.

Abstract: A method is provided for identifying resonant frequency vibration events in an assembly of rotating blades mounted on a rotor. A plurality of circumferentially spaced stationary timing probes associated with the blades detect the times at which the blades pass the respective probes. The method includes the steps of: obtaining blade timings detected by the probes; determining, for successive rotations of the assembly, respective correlation factors for one or more of the blades, each correlation factor quantifying the degree of correlation between the blade timings detected by the probes for a particular blade on a particular rotation and the blade timings detected by the probes for that blade on the previous rotation; and identifying a resonant vibration event when the one or more correlation factors cross a predetermined threshold.

Abstract: A method of forming a blade assembly for a gas turbine engine, the method comprising mounting turbine blades on a rotor in a number of radial stages. Sacrificial supports are placed on the blades, and nozzle guide vanes are located on the supports. The rotor is introduced into a casing, and the guide vanes are mounted to the casing.

Abstract: A method for characterising the surface profile of a component comprises the steps of a) dividing the surface into at least two regions; b) for each region, measuring the surface and selecting a number of measured points to define a co-ordinate dataset for the region; c) for each region, applying a curve-fitting algorithm to the dataset for the region to define the surface profile of the region; d) combining the defined surface profiles for the regions to produce a defined surface profile for the aerofoil surface. The characterisation may be used in the design, analysis and manufacturing steps of product development, thereby decreasing the total time and work required.

Abstract: An engine mounting apparatus having a yoke carrier block and a main mount block, the yoke carrier block being connectable to the main mount block, the main mount block being connected to the engine by at least one engine attachment link for transferring loads from an engine in a normal load path during normal operation of the engine mounting arrangement, characterised in that the yoke carrier block is connected to a further engine attachment link independently of the main mount block, the further engine attachment link being unloaded during normal operation of the engine mounting arrangement and arranged to transfer loads from the engine in the event of a failure of one or more components in the normal load path.

Abstract: An engine mounting apparatus that includes thrust struts, a balance yoke, and primary and secondary mount blocks. The thrust struts are connected to the balance yoke and the primary mount block has at least one thrust load connection connectable to the balance yoke for transferring thrust loads from an engine during normal operation of the engine mounting apparatus. The engine mounting apparatus is, characterised in that the secondary mount block is connected to the balance yoke via at least one thrust load catcher connection, the at least one thrust load catcher connection being arranged to be unloaded during normal operation of the engine mounting arrangement and to transfer the thrust loads from the engine in the event of a failure condition of the primary mount block.

Abstract: Mounting of gas turbine engines in aircraft requires use of thrust struts associated with mountings. It is important should there be failure that a load path is maintained. Furthermore, on a wing or in-situ inspection is highly desirable with respect to reducing maintenance costs. Of particular concern is failure as a result of cracking both sideways and vertical which may result in loss of all load paths through the mounting. By provision of independent cranks which are associated through crank pivots in apertures of the cranks and then articulation about central pivots provided in apertures and a central element along with pivot association of the struts through pivots created about apertures in the cranks load paths are maintained. By independent provision of the cranks sideways and vertical cracking cannot cause failure in both load paths to the arrangement from the struts.

Abstract: A rotor blade tip arrangement is provided in which winglets extend from the end of rotor blade aerofoil walls. These winglets incorporate passages which extend to coolant apertures or holes in order to present a coolant flow about the tip of the turbine rotor blade. The winglets define at least an open ended gutter channel in order to inhibit leakage flow across the tip arrangement from a pressure side P to a suction side S. The coolant flow facilitates cooling of the arrangement despite any heating caused by leakage flow across the arrangement.