GB2533322A

GB2533322A - A method of repairing a component of a gas turbine engine

Info

Publication number: GB2533322A
Application number: GB1422348.1A
Authority: GB
Inventors: Mohamed Salleh Najib; Xianyao Gooi; Seet Bin Azry Seet Airil
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2014-12-16
Filing date: 2014-12-16
Publication date: 2016-06-22

Abstract

A method and apparatus for repairing a variable vane of a gas turbine engine includes a controller 12. The controller controls removal of a part of a variable vane 16 of a gas turbine engine to provide a first surface and controls inertia friction welding 14 of a member 20 to the first surface of the variable vane. The part may be a portion of a root and may include a bearing surface. A fixture (18, Figure 2A) having first and second housings (44, 46) and resilient protrusions (48, 50, 52) defines a cavity 56 to receive a variable vane (16). A sleeve (54, Figure 2B) receives the housings and protrusions, via apertures (58), to secure them to the sleeve. A method of repairing a component of a gas turbine engine includes controlling removal of a part of the component to provide a first surface and controlling friction welding of a member to the first surface of the component, the component being supported by a fixture during friction welding.

Description

A METHOD OF REPAIRING A COMPONENT OF A GAS TURBINE ENGINE

Various examples concern a method and apparatus of repairing a component of a gas turbine engine.

Gas turbine engines comprise a plurality of different components that may require repair during the operational life of the gas turbine engine. For example, a bearing surface of a variable vane (which may also be referred to as a trunnion) may become worn during the operational life of the gas turbine engine and require repair. Currently, the bearing surface of a variable vane may be repaired by spraying the worn or damaged bearing surface with metal.

According to various, but not necessarily all, embodiments of the invention there is provided a method of repairing a variable vane of a gas turbine engine, the method comprising: controlling removal of a part of a variable vane of a gas turbine engine to provide a first surface; and controlling inertia friction welding of a member to the first surface of the variable vane.

The part of the variable vane is at least a portion of a root of the variable vane. 20 The part of the variable vane may include a bearing surface.

The member may comprise the same material as the variable vane.

The member may comprise a cylindrical body without a bearing surface.

The method may further comprise controlling machining of the welded member to form a bearing surface of the variable vane.

The method may further comprise: determining whether the part of the variable 30 vane is beyond one or more predetermined thresholds, and wherein removal of the part of the variable vane may be controlled when it is determined that the part is beyond the one or more predetermined thresholds.

The method may further comprise: controlling provision of the variable vane within a fixture; and controlling coupling of the fixture and variable vane combination to a clamp of an inertia friction welding machine.

The fixture may comprise: a first housing including at least one resilient protrusion; a second housing including at least one resilient protrusion, the first housing and the second housing defining a cavity there between to receive the variable vane therein; and a sleeve to receive the first and second housings therein, the sleeve defining a plurality of apertures for receiving the resilient protrusions of the first and second housings therein to secure the first and second housings to the sleeve.

According to various, but not necessarily all, embodiments of the invention there is provided a computer program that, when read by a computer, causes performance of the method as described in any of the preceding paragraphs.

According to various, but not necessarily all, embodiments of the invention there is provided a non-transitory computer readable storage medium comprising computer readable instructions that, when read by a computer, causes 20 performance of the method as described in any preceding paragraphs.

According to various, but not necessarily all, embodiments of the invention there is provided apparatus for repairing a variable vane of a gas turbine engine, the apparatus comprising: a controller to: control removal of a part of a variable vane of a gas turbine engine to provide a first surface; and control inertia friction welding of a member to the first surface of the variable vane.

The variable vane may be at least a portion of a root of the variable vane. The part of the variable vane may include a bearing surface.

The member may comprise the same material as the variable vane.

The member may comprise a cylindrical body without a bearing surface.

The controller may be to control machining of the welded member to form a bearing surface of the variable vane.

The controller may be to determine whether the part of the variable vane is beyond one or more predetermined thresholds, and wherein removal of the part of the variable vane may be controlled when it is determined that the part is beyond the one or more predetermined thresholds.

The controller may be to control provision of the variable vane within a fixture; and to control coupling of the fixture and variable vane combination to a clamp of an inertia friction welding machine.

According to various, but not necessarily all, embodiments of the invention there is provided a fixture comprising: a first housing including at least one resilient protrusion; a second housing including at least one resilient protrusion, the first housing and the second housing defining a cavity there between to receive a variable vane therein; and a sleeve to receive the first and second housings therein, the sleeve defining a plurality of apertures for receiving the resilient protrusions of the first and second housings therein to secure the first and second housings to the sleeve.

The cavity defined by the first and second housings may have a shape corresponding to the shape of the variable vane.

According to various, but not necessarily all, embodiments of the invention there is provided a method of repairing a component of a gas turbine engine, the method comprising: controlling removal of a part of a component of a gas turbine engine to provide a first surface; controlling friction welding of a member to the first surface of the component, the component being supported by a fixture during friction welding.

The skilled person will appreciate that except where mutually exclusive, a feature described in relation to any one of the above aspects of the invention may be applied mutatis mutandis to any other aspect of the invention.

Embodiments of the invention will now be described by way of example only, with reference to the Figures, in which: Fig. 1 illustrates a schematic diagram of apparatus for repairing a component of a gas turbine engine according to various examples; Figs. 2A to 2E illustrate various views of a fixture and a component of a gas turbine engine according to various examples; Fig. 3 illustrates a flow diagram of a method of repairing a component of a gas turbine engine according to various examples; Figs. 4A to 4E illustrate side view diagrams of an outer bearing of a variable vane being repaired according to various examples; and Figs. 5A to 5E illustrate side view diagrams of an inner bearing of a variable vane being repaired according to various examples.

In the following description, the terms 'connect' and 'couple' mean operationally connected and coupled. It should be appreciated that there may be any number of intervening components between the mentioned features, including no intervening components.

Fig. 1 illustrates a schematic diagram of apparatus 10 for repairing a component of a gas turbine engine. In particular, the apparatus 10 is arranged to remove a part of a component of a gas turbine engine (such as a variable vane) to provide a first surface, and to inertia friction weld a member to the first surface of the component. The apparatus 10 includes a controller 12, friction welding machinery 14, a component 16, a fixture 18, a member 20, a sensor 22, and machinery 24.

In some examples, the apparatus 10 may be a module. As used herein, the wording module' refers to a device or apparatus where one or more features are included at a later time, and possibly, by another manufacturer or by an end user. For example, where the apparatus 10 is a module, the apparatus 10 may only include the controller 12, and the remaining features may be added by another manufacturer, or by an end user.

The controller 12 may comprise any suitable circuitry to cause performance of the methods described herein and as illustrated in Fig. 3. The controller 12 may comprise any combination of hardware, software and firmware. For example, the controller 12 may comprise at least one application specific integrated circuit (ASIC) and/or at least one field programmable gate array (FPGA) to perform the methods. By way of another example, the controller 12 may comprise at least one processor 26 and at least one memory 28. The memory 28 stores a computer program 30 comprising computer readable instructions that, when read by the processor 26, causes performance of the methods described herein, and as illustrated in Fig. 3. The computer program 30 may be software or firmware, or may be a combination of software and firmware.

The processor 26 may be located at a repair centre with the remaining components of the apparatus 10, or may be located remote from the repair centre, or may be distributed between the repair centre and a location remote from the repair centre. The processor 26 may include at least one microprocessor and may comprise a single core processor, or may comprise multiple processor cores (such as a dual core processor or a quad core processor).

The memory 28 may be located at the repair centre, or may be located remote from the repair centre, or may be distributed between the repair centre and a location remote from the repair centre. The memory 28 may be any suitable non-transitory computer readable storage medium, data storage device or devices, and may comprise a hard disk and/or solid state memory (such as flash memory). The memory 28 may be permanent non-removable memory, or may be removable memory (such as a universal serial bus (USB) flash drive).

The computer program 30 may be stored on a non-transitory computer readable storage medium 32. The computer program 30 may be transferred from the non-transitory computer readable storage medium 32 to the memory 28. The non-transitory computer readable storage medium 32 may be, for example, a USB flash drive, a compact disc (CD), a digital versatile disc (DVD) or a Blu-ray disc. In some examples, the computer program 30 may be reliably transferred to the memory 28 via a wireless or a wired signal 34.

The friction welding machinery 14 may include any suitable friction welding machine or machines for friction welding the component 16 and the member 20 together. The friction welding machinery 14 may include, for example, an inertia friction welding machine and/or a stir friction welding machine. The friction welding machinery 14 includes a clamp 36 (for example, a chuck) for supporting and retaining the component 16. The controller 12 may be configured to control the operation of the friction welding machinery 14.

The component 16 may be any suitable component (such as a vane or a blade) of a gas turbine engine. For example, the component 16 may be a variable vane of a gas turbine engine, such as a variable stator vane (VSV) or a variable inlet guide vane (VIGV). In other examples, the component 16 may be a static component of a gas turbine engine, and may be, for example, a nozzle guide vane (NGV).

The fixture 18 may be any fixture apparatus for supporting and retaining the component 16 while the component 16 is being machined by the friction welding machinery 14. For example, the fixture 18 may be structured as illustrated in Figs. 2A to 2E. The fixture 18 may be configured to be received in, and retained by the clamp 36 of the friction welding machinery 14.

The member 20 is used in the repair of the component 16 to replace a worn or damaged part of the component 16. The member 20 may have any suitable shape and may comprise any suitable material. For example, the member 20 may comprise the same material as the component 16, or may comprise a different material to the component 16 (for example, where the part which the member 20 is replacing comprises a different material to the remainder of the component 16).

Where the member 20 is used in the repair of a variable vane, the member 20 may comprise a cylindrical body with a bearing surface (where the cylindrical body is manufactured with the bearing surface, or is machined to include the bearing surface, prior to friction welding), or without a bearing surface (where the cylindrical body is machined after friction welding to define the bearing surface).

The sensor 22 may be any suitable sensor for enabling the controller 12 to determine whether at least a part of the component 16 is beyond one or more predetermined thresholds (for example, one or more thresholds for whether the component 16 is 'acceptable' for use in operation of the gas turbine engine). For example, the sensor 22 may include a three dimensional (3D) scanning system comprising a laser and an image sensor for imaging the component 16. The controller 12 may be configured to receive image data from the sensor 22 and compare the sensed three dimensional shape of the component 16 with one or more predetermined threshold values (for example, an 'acceptable' threshold depth of a bearing surface). Where the three dimensional shape in the image data exceeds the one or more threshold values, the controller 12 may then determine that the component 16 is beyond one or more predetermined thresholds.

The machinery 24 may include any suitable robotics and tools for manipulating and machining the component 16, the fixture 18 and the member 20. For example, the machinery 24 may include: one or more robotic arms configured to handle and move the component 16, the fixture 18 and the member 20; a lathe machine for removing a part of the component 16, and a computer numerical control (CNC) machine for machining the member 20. The controller 12 may be configured to control the operation of the machinery 24.

Figs. 2A to 2E illustrate various views of a component 16 and a fixture 18 according to various examples. In this example, the component 16 is a variable vane of a gas turbine engine and includes an aerofoil part 38, an inner bearing part 40 and an outer bearing part 42. The fixture 18 may have any suitable shape for supporting and retaining the component 16, and at least a part of the fixture 18 may be formed via three dimensional (3D) printing.

The fixture 18 includes: a first housing 44 including at least one resilient protrusion 48 (such as a pin-ball lock); and a second housing 46 including at least one resilient protrusion (in this example, the second housing 46 includes two resilient protrusions 50, 52, such as two pin-ball locks). The first housing 44 and the second housing 46 define a cavity 56 there between to receive the variable vane 16 therein. In some examples, the cavity 56 defined by the first and second housings 44, 46 has a shape corresponding to the shape of the variable vane 16 (in other words, they have the same, or a similar shape) and the variable vane 16 may snugly fit within the cavity 56. The first and second housings 44, 46 may be formed via three dimensional (3D) printing.

The fixture 18 also includes a sleeve 54 to receive the first and second housings 44, 46 therein. The sleeve 54 defines a plurality of apertures 58 for receiving the resilient protrusions 48, 50, 52 of the first and second housings 44, 46 therein to secure the first and second housings 44, 46 to the sleeve 54.

In operation, the variable vane 16 is first inserted into the cavity defined by one of the first and second housings 44, 46, and is then sandwiched by the other of the first and second housings 44, 46 (as illustrated in Fig. 2A). Next, the first and second housings 44, 46 and the variable vane 16 are slid inside the sleeve 54 (Fig. 2B) and the resilient protrusions 48, 50, 52 deform inwardly to enable the first and second housings 44, 46 to move within the sleeve 54. Then, the first and second housings 44, 46 and the variable vane 16 are moved within the sleeve 54 until the resilient protrusions 48, 50, 52 are co-located with the apertures 58 of the sleeve 54 and return to their original shape, thereby locking the first and second housings 44, 46 (and consequently, the variable vane 16) into position within the sleeve 54.

The variable vane 16 may be removed from the fixture 18 by pressing the resilient protrusions 48, 50, 52 radially inwardly, then sliding the first and second housings 44, 46 out of the sleeve 54, and then separating the first and second housings 44, 46 to enable the variable vane 16 to be removed from the cavity 56.

Fig. 3 illustrates a flow diagram of a method of repairing a component 16 of a gas turbine engine. In the following description, the component 16 is a variable vane (such as a variable stator vane (VSV) or a variable inlet guide vane (VIGV)). However, it should be appreciated that in other examples, the component 16 may be another component of a gas turbine engine.

At block 60, the sensor 22 may obtain a two dimensional image or a three dimensional image of the variable vane 16 illustrated in Fig. 4A. The image includes the outer bearing 42 of the variable vane 16 which defines the outer bearing surface 62. The controller 12 receives the image data from the sensor 22 and determines whether the outer bearing part 42 is beyond one or more predetermined thresholds. For example, the controller 12 may measure the depth of the outer bearing surface 62 using the received image data and determine whether the measured depth is beyond an acceptable threshold depth.

If the controller 12 determines that the outer bearing part 42 is within one or more predetermined thresholds (for example, within an acceptable threshold for the depth of the outer bearing surface 62), block 60 is repeated for another component of a gas turbine engine (for example, another vane). If the controller 12 determines that the outer bearing part 42 is beyond one or more predetermined thresholds, the method may move to block 64.

At block 64, the controller 12 may control the machinery 24 to provide the variable vane 16 within the fixture 18. For example, the controller 12 may control a robotic arm of the machinery to move the variable vane 16 from the sensor 22 to the fixture 18, and then place the variable vane 16 within the fixture 18.

At block 66, the controller 12 controls the machinery 24 to remove the outer bearing part 42 of the variable vane 16 (that is, a trunnion of the variable vane 16) to provide a first surface 68, as illustrated in Fig. 4B. For example, the controller 12 may control a lathe machine of the machinery 24 to cut off the outer bearing part 42 from the variable vane 16 and remove the outer bearing part 42 in the direction of arrow 69. In some examples, block 66 may be performed subsequent to block 60 and prior to block 64 (that is, the outer bearing part 62 may be removed prior to the variable vane 16 being provided within the fixture 18).

At block 70, the controller 12 may control coupling of the combination of the fixture 18 and the variable vane 16 to the clamp 36 of the inertia friction welding machinery 14. For example, the controller 12 may control a robotic arm of the machinery 24 to move the fixture 18 and variable vane 16 combination into the chuck 36 of the inertia friction welding machinery 14 and then tighten the chuck 36. The controller 12 may also control coupling of the member 20 to another clamp of the inertia friction welding machinery 14. In some examples, the combination of the fixture 18 and the variable vane 16 are coupled to a non-rotatable clamp (that is, a clamp that is stationary relative to the housing of the inertia friction welding machinery), and the member 20 is coupled to a rotatable clamp (that is, a clamp that may be rotated relative to the housing of the inertia friction welding machinery and to the variable vane 16).

At block 72, the controller 12 controls inertia friction welding (which may also be referred to as 'spin welding' or 'rotational welding') of the member 20 to the first surface 68 of the variable vane 16. For example, the controller 12 may send a control signal to the inertia friction welding machine 14 to cause the inertia friction welding machine 14 to weld the member 20 to the first surface 68 of the variable vane 16. As illustrated in Fig. 4C, the inertia friction welding machine 14 moves the member 20 in the direction of arrow 73 (parallel to an axis 71 of the member 20) towards and into contact with the first surface 68, while also rotating the member 20 about the axis 71 in the direction of arrow 74, to weld the member 20 to the first surface 68. Fig. 4D illustrates the variable vane 16 having the member 20 welded on the first surface 68.

At block 76, the controller 12 may control machining of the welded member 20 to form a bearing surface 62 of the variable vane 16. For example, the controller 12 may control a machining tool of the machinery 24 to machine the top surface of the member 20 to form the bearing surface 62 as illustrated in Fig. 4E.

Figs. 5A to 5E illustrate side view diagrams of an inner bearing 40 of a variable vane being repaired according to the method illustrated in Fig. 3.

At block 60, the sensor 22 may obtain a two dimensional image or a three dimensional image of the variable vane 16 illustrated in Fig. 5A. The image includes the inner bearing 40 (which may also be referred to as a journal) of the variable vane 16. The controller 12 receives the image data from the sensor 22 and determines whether the inner bearing part 40 is beyond one or more predetermined thresholds (for example, one or more acceptable thresholds). For example, the controller 12 may measure the shape of the inner bearing using the received image data and determine whether the measured shape is beyond an acceptable threshold depth.

If the controller 12 determines that the inner bearing part 40 is within the one or more predetermined thresholds, block 60 is repeated for another component of a gas turbine engine. If the controller 12 determines that the inner bearing part 40 is beyond the one or more predetermined thresholds, the method may move to block 64.

At block 64, the controller 12 may control the machinery 24 to provide the variable vane 16 within the fixture 18 (not illustrated in Figs. 5A to 5E). For example, the controller 12 may control a robotic arm of the machinery 24 to move the variable vane 16 from the sensor 22 to the fixture 18, and then place the variable vane 16 within the fixture 18.

At block 66, the controller 12 controls the machinery 24 to remove the inner bearing part 40 of the variable vane 16 to provide a first surface 78, as illustrated in Fig. 5B. For example, the controller 12 may control a lathe machine of the machinery 24 to cut off the inner bearing part 40 from the variable vane 16 and remove the inner bearing part 40 in the direction of arrow 69. In some examples, block 66 may be performed subsequent to block 60 and prior to block 64 (that is, the inner bearing part 40 may be removed prior to the variable vane 16 being provided within the fixture 18).

At block 70, the controller 12 controls coupling of the combination of the fixture 18 and the variable vane 16 to the clamp 36 of the inertia friction welding machinery 14. For example, the controller 12 may control a robotic arm of the machinery 24 to move the fixture 18 and variable vane 16 combination into the chuck 36 of the inertia friction welding machinery 14 and then tighten the chuck 36. The controller 12 may also control coupling of the member 20 to another clamp of the inertia friction welding machinery 14. In some examples, the combination of the fixture 18 and the variable vane 16 are coupled to a non-rotatable clamp (that is, a clamp that is stationary relative to the housing of the inertia friction welding machinery), and the member 20 is coupled to a rotatable clamp (that is, a clamp that may be rotated relative to the housing of the inertia friction welding machinery and to the variable vane 16).

At block 72, the controller 12 controls inertia friction welding of the member 20 to the first surface 78 of the variable vane 16. For example, the controller 12 may send a control signal to the inertia friction welding machine 14 to cause the inertia friction welding machine 14 to weld the member 20 to the first surface 78 of the variable vane 16. As illustrated in Fig. 5C, the inertia friction welding machine 14 moves the member 20 in the direction of arrow 73 (parallel to an axis 71 of the member 20) towards and into contact with the first surface 78, while also rotating the member 20 about the axis 71 in the direction of arrow 74, to weld the member 20 to the first surface 78. Fig. 5D illustrates the variable vane 16 having the member 20 welded on the first surface 78.

At block 76, the controller 12 may control machining of the welded member 20 to reshape the member to form the inner bearing part 40. For example, the controller 12 may control a machining tool of the machinery 24 to machine the surfaces of the member 20 to form an inner bearing part as illustrated in Fig. 5E.

The apparatus 10 and method illustrated in Fig. 3 may provide several advantages. First, repairing the component 16 may be less costly using the method illustrated in Fig. 3 than repairing using a metal spraying process (where metal may be wasted during spraying). Second, repairing the component 16 using the method illustrated in Fig. 3 may require less time than repairing the component using a metal spraying process. In particular, the method illustrated in Fig. 3 may reduce the repair cycle time by thirty one percent because the method illustrated in Fig. 3 eliminates the preparation of the component 16 for metal spraying. Third, since the method of Fig. 3 does not include metal spraying, the metal spraying apparatus may be available for other operations within the repair centre, thus increasing productivity within the repair centre, or eliminating the requirement of having a metal spraying apparatus within the repair centre. Fourth, use of the fixture 18 in the method of Fig. 3 may prevent the component 16 from twisting and being displaced laterally in the friction welding machinery 14. Additionally, the fixture 18 may be structurally capable of withstanding the applied external compressive and torsional forces during the friction welding process.

It will be understood that the invention is not limited to the embodiments above-described and various modifications and improvements can be made without departing from the various concepts described herein. For example, at least some of the blocks illustrated in Fig. 3 and described above may be controlled by a human operator instead of the controller 12. Furthermore, in some examples, the apparatus 10 may not include a fixture 18 and in those examples, the method may not include block 64, and in block 70, the component 16 may be fastened by the clamp 36 on its own.

Where the component 16 is a component of a gas turbine engine other than a variable vane, an alternative friction welding technique may be used to weld the member 20 to the component 16. For example, where the component 16 is a nozzle guide vane, stir friction welding may be used instead of inertia friction welding to repair an intrascope bushing of the nozzle guide vane.

Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the invention extends to and includes all combinations and sub-combinations of one or more features described herein in any form.

Claims

Claims 1. A method of repairing a variable vane of a gas turbine engine, the method comprising: controlling removal of a part of a variable vane of a gas turbine engine to provide a first surface; and controlling inertia friction welding of a member to the first surface of the variable vane.
2. A method as claimed in claim 1, wherein the part of the variable vane is at least a portion of a root of the variable vane.
3. A method as claimed in claim 2, wherein the part of the variable vane includes a bearing surface.
4. A method as claimed in any of the preceding claims, wherein the member comprises the same material as the variable vane.
5. A method as claimed in any of the preceding claims, wherein the member comprises a cylindrical body without a bearing surface.
6. A method as claimed in any of the preceding claims, further comprising: controlling machining of the welded member to form a bearing surface of the variable vane.
7. A method as claimed in any of the preceding claims, further comprising: determining whether the part of the variable vane is beyond one or more predetermined thresholds, and wherein removal of the part of the variable vane is controlled when it is determined that the part is beyond the one or more predetermined thresholds.
8. A method as claimed in any of the preceding claims, further comprising: controlling provision of the variable vane within a fixture; and controlling coupling of the fixture and variable vane combination to a clamp of an inertia friction welding machine.
9. A method as claimed in claim 8, wherein the fixture comprises: a first housing including at least one resilient protrusion; a second housing including at least one resilient protrusion, the first housing and the second housing defining a cavity there between to receive the variable vane therein; and a sleeve to receive the first and second housings therein, the sleeve defining a plurality of apertures for receiving the resilient protrusions of the first and second housings therein to secure the first and second housings to the sleeve.
10. A method substantially as described herein with reference to and/or as illustrated in the accompanying figures.
11. A computer program that, when read by a computer, causes performance of the method as claimed in any of the preceding claims.
12. A non-transitory computer readable storage medium comprising computer readable instructions that, when read by a computer, causes performance of the method as claimed in any of claims 1 to 10.
13. Apparatus for repairing a variable vane of a gas turbine engine, the apparatus comprising: a controller to: control removal of a part of a variable vane of a gas turbine engine to provide a first surface; and control inertia friction welding of a member to the first surface of the variable vane.
14. Apparatus as claimed in claim 13, wherein the part of the variable vane is at least a portion of a root of the variable vane.
15. Apparatus as claimed in claim 14, wherein the part of the variable vane includes a bearing surface.
16. Apparatus as claimed in any of claims 13 to 15, wherein the member comprises the same material as the variable vane.
17. Apparatus as claimed in any of claims 13 to 16, wherein the member comprises a cylindrical body without a bearing surface.
18. Apparatus as claimed in any of claims 13 to 17, wherein the controller is to control machining of the welded member to form a bearing surface of the variable vane.
19. Apparatus as claimed in any of claims 13 to 18, wherein the controller is to determine whether the part of the variable vane is beyond one or more predetermined thresholds, and wherein removal of the part of the variable vane is controlled when it is determined that the part is beyond the one or more predetermined thresholds.
20. Apparatus as claimed in any of claims 13 to 19, wherein the controller is to control provision of the variable vane within a fixture; and to control coupling of the fixture and variable vane combination to a clamp of an inertia friction welding machine.
21. Apparatus as claimed in claim 20, wherein the fixture comprises: a first housing including at least one resilient protrusion; a second housing including at least one resilient protrusion, the first housing and the second housing defining a cavity there between to receive the variable vane therein; and a sleeve to receive the first and second housings therein, the sleeve defining a plurality of apertures for receiving the resilient protrusions of the first and second housings therein to secure the first and second housings to the sleeve.
22. Apparatus for repairing a variable vane of a gas turbine engine substantially as described herein with reference to and/or as illustrated in the accompanying figures.
23. A fixture comprising: a first housing including at least one resilient protrusion; a second housing including at least one resilient protrusion, the first housing and the second housing defining a cavity there between to receive a variable vane therein; and a sleeve to receive the first and second housings therein, the sleeve defining a plurality of apertures for receiving the resilient protrusions of the first and second housings therein to secure the first and second housings to the sleeve.
24. A fixture as claimed in claim 23, wherein the cavity defined by the first and second housings has a shape corresponding to the shape of the variable vane.
25. A fixture substantially as described herein with reference to and/or as illustrated in the accompanying figures.
26. A method of repairing a component of a gas turbine engine, the method comprising: controlling removal of a part of a component of a gas turbine engine to provide a first surface; controlling friction welding of a member to the first surface of the component, the component being supported by a fixture during friction welding.