Abstract:
An electrical raft is provided comprising a rigid material having multiple electrical conductors embedded therein. An electrical connector is provided to the raft that has a back-shell which is embedded in the rigid material and which joins to a connector body to enclose a first end of a housing of the connector body. The housing also has a second end at which electrical contacts are provided for connection to another component. The connector body is detachable from the back-shell to electrically disconnect it from the embedded electrical conductors and allow removal of the connector body from the electrical raft. In this way, the connector body may be readily removed, for example for upgrade or repair, whilst retaining a robust and reliable connection.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based upon and claims the benefit of priority from British Patent Application Number 1308025.4 filed 3 May 2013, the entire contents of which is incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Disclosure 
         [0003]    The present disclosure relates to electrical connectors. In particular, aspects of the disclosure relate to electrical connectors in rigid electrical rafts used to distribute electrical signals around a gas turbine engine. 
         [0004]    2. Description of the Related Art 
         [0005]    A typical gas turbine engine has a substantial number of electrical components which serve, for example, to sense operating parameters of the engine and/or to control actuators which operate devices in the engine. Such devices may, for example, control fuel flow, variable vanes and air bleed valves. The actuators may themselves be electrically powered, although some may be pneumatically or hydraulically powered, but controlled by electrical signals. 
         [0006]    Electrical power, and signals to and from the individual electrical components, is commonly transmitted along conductors. Conventionally, such conductors may be in the form of wires and/or cables which are assembled together in a harness. In such a conventional harness, each wire may be surrounded by an insulating sleeve, which may be braided or have a braided cover. 
         [0007]    By way of example,  FIG. 1  of the accompanying drawings shows a typical gas turbine engine including two conventional wiring harnesses  102 ,  104 , each provided with a respective connector component  106 ,  108  for connection to circuitry, which may be for example accommodated within the airframe of an aircraft in which the engine is installed. 
         [0008]    The harnesses  102 ,  104  are assembled from individual wires and cables which are held together over at least part of their lengths by suitable sleeving and/or braiding. Individual wires and cables, for example those indicated at  110 , emerge from the sleeving or braiding to terminate at plug or socket connector components  112  for cooperation with complementary socket or plug connector components  114  on, or connected to, the respective electrical components. 
         [0009]    Each conventional harness  102 ,  104  comprises a multitude of insulated wires and cables. This makes the conventional harness itself bulky, heavy and difficult to manipulate. The conventional harnesses occupy significant space within a gas turbine engine (for example within the nacelle of a gas turbine engine), and thus may compromise the design of the aircraft, for example the size and/or weight and/or shape of the nacelle. 
         [0010]    Conventional harnesses comprise a large number of components, including various individual wires and/or bundles of wires, supporting components (such as brackets or cables) and electrical and/or mechanical connectors. This can make the assembly process complicated (and thus susceptible to errors) and/or time consuming. Disassembly of the conventional harnesses (for example removal of the conventional harnesses from a gas turbine engine during maintenance) may also be complicated and/or time consuming. Thus, in many maintenance (or repair or overhaul) procedures on a gas turbine engine, removal and subsequent refitting of the conventional electrical harness may account for a very significant portion of the operation time and/or account for a significant proportion of the potential assembly errors. 
         [0011]    The electrical conductors in the conventional harnesses may be susceptible to mechanical damage. For example, mechanical damage may occur during installation (for example through accidental piercing of the protective sleeves/braiding) and/or during service (for example due to vibration). In order to reduce the likelihood of damage to the conductors in a conventional harness, the protective sleeves/braiding may need to be further reinforced, adding still further weight and reducing the ease with which they can be manipulated. Similarly, the exposed electrical connectors used to connect one conductor to another conductor or conductors to electrical units may be susceptible to damage and/or may add significant weight to the engine. 
       OBJECTS AND SUMMARY 
       [0012]    In a first aspect, the present invention provides an electrical raft comprising:
       a rigid material having multiple electrical conductors embedded therein, and   an electrical connector having a connector body including a first set of electrical contacts connected to at least one of the electrical conductors, a second set of electrical contacts for electrical connection to another component, and a housing having a first end and a second end, the first set of electrical contacts being at the first end, the second set of electrical contacts being at the second end, and the second end being accessible from outside the electrical raft, thereby allowing the electrical raft to be electrically connected to said other component;   wherein:   the electrical connector further has a back-shell which is embedded in the rigid material and which joins to the connector body to enclose the first end of the housing, and   the connector body is detachable from the back-shell to disconnect the first set of electrical contacts from the electrical conductors and allow removal of the connector body from the electrical raft.       
 
         [0018]    By embedding the back-shell of the connector in the rigid material of the raft, it is possible to integrate this part of the connector with the raft. Because the back-shell may be assembled with the raft, its position, and hence the position of the connector, can be determined accurately, reducing error during connection to other units. In addition, the connector body, being detachable from the back-shell to allow removal of the connector body from the raft, facilitates replacement, repair or upgrading of the connector body. 
         [0019]    The housing may be a convenient arrangement for providing the second set of electrical contacts in a position that allows them to be connectable to another component, and the first set of electrical contacts at a position that allows them to be connected to one or more of the embedded electrical conductors. The housing may provide protection to the internal parts of the connector (which may, for example, include components for electrically connecting the first set of electrical contacts with the second set of electrical contacts). 
         [0020]    In a second aspect, the present invention provides an electrical raft assembly comprising: an electrical raft according to any example of the first aspect, and a further electrical component comprising a complimentary set of electrical contacts that correspond to the second set of electrical contacts, wherein the electrical raft and the further electrical component are in electrical connection through the second set of electrical contacts and the complimentary set of electrical contacts. 
         [0021]    The complimentary set of electrical contacts may be in the form of a plug or socket. The second set of electrical contacts of the electrical raft may thus be in the form of the other of a plug and socket. The further electrical component may be any sort of electrical component, for example a set of electrical conductors that link the electrical raft to a still further electrical component. Such a set of electrical conductors may be, for example, in the form of one or more wires, which may be bundled together and/or which may be sheathed/braided, and/or in the form of an FPC. Additionally or alternatively, the further electrical component may be, for example, an electrical unit. Such an electrical unit may be mechanically fixed/mounted to the surface of the electrical raft. The mechanical fixing may be independent of the electrical connection. 
         [0022]    In a third aspect, the present invention provides a gas turbine engine or gas turbine engine installation, having the raft according to the first aspect or the raft assembly of the second aspect. For example, the electrical rigid raft or electrical raft assembly may be a first engine installation component, and the gas turbine engine or gas turbine engine installation may further comprise a second engine installation component having electrical conductors. At least one flexible cable can then connect between the electrical raft or electrical raft assembly and the second engine installation component so as to electrically connect electrical conductors of the electrical raft or electrical raft assembly with electrical conductors of the second engine installation component. 
         [0023]    In a fourth aspect, the present invention provides a method of manufacturing (including assembling, repairing, reassembling and/or overhauling) a gas turbine engine comprising: attaching an electrical raft according to the first aspect (or an electrical raft assembly according to the second aspect) to the engine, and electrically connecting a further electrical component of the gas turbine engine to the electrical raft (or electrical raft assembly) by connecting the second set of contacts to a complimentary set of contacts of the further electrical component. The further electrical component may be as described elsewhere herein, for example a flexible cable (such as a FPC), or an ECU, such as en electronic engine controller (EEC), or Engine Health Monitoring Unit (EMU). 
         [0024]    Further optional features of the invention will now be set out. These are applicable singly or in any combination with any aspect of the invention. 
         [0025]    The rigid material may be a rigid polymer matrix composite material. The back-shell can advantageously prevent ingress of the polymer as a fouling contaminant into the connector during manufacture of the raft. During manufacture, such contaminants can interfere with the positions of the electrical contacts, whereby the mated contacts may be unable to move sufficiently to ensure good electrical contact. During use, such contaminants can interfere with the proper electrical functioning of the connector, e.g. by preventing electrical contacts or producing short-circuits. 
         [0026]    The rigid material may contain layers of continuous reinforcing fibres, as discussed below. 
         [0027]    The electrical connector may have an elastomeric seal between the housing and the back-shell. Such a seal can be particularly effective at preventing ingress of polymer during manufacture. Indeed, it is particularly desirable to prevent any such ingress when such a seal is used, as ingressing polymer can reduce compliance at the seal, reducing sealing effectiveness and allowing other contaminants (e.g. oil or fuel) to enter the connector during use. 
         [0028]    The connector body may be joined to the back-shell by fasteners, such as bolts, that are accessible from outside the electrical raft. 
         [0029]    The back-shell may have one or more location formations that prevent movement of the back-shell relative to the rigid material. For example, the back-shell may have a flange that retains the back-shell in the rigid material and presents the connector at a correct orientation relative to a major surface of the raft from which the connector body is removable, and/or one or more flats, keyways or other shaped formations which prevent rotation of the back-shell in the rigid material. 
         [0030]    The housing and the back-shell may be electrically conductive and may be in electrical contact with each other to provide electro-magnetic shielding of the connector. For example, the housing and the back-shell can be formed of metal. However another option is to form the housing and the back-shell of conductive or plated composite, plastic or ceramic, which may provide weight advantages. 
         [0031]    At least some of the electrical conductors embedded in the electrical raft may be electrical wires. The electrical wires may be provided with a protective and/or insulating sheath/braiding. As such, individual wires may be laid into (or embedded in) the electrical raft, and each wire may be used to transfer one or more electrical signals through the raft and around an engine. 
         [0032]    At least some of the electrical conductors may be provided in a flexible printed circuit (FPC) in the form of electrical tracks formed in a flexible substrate. The electrical tracks may then terminate in openings in a flexible printed circuit connector. The FPC may be provided with a dedicated connector to connect the electrical tracks to the electrical connector. The electrical tracks may terminate in conductive openings in such a dedicated connector. Such a dedicated connector may be referred to as a lollipop connector, and may be generally planar. The first set of electrical contacts may comprise pins that are received in respective openings so as to electrically connect the electrical tracks to the electrical connector. This may be a particularly compact and/or lightweight and/or robust arrangement for connecting electrical tracks in an embedded flexible printed circuit to the electrical connector. Further, a pin and opening connection arrangement can be a convenient way disconnectably connecting the first set of electrical contacts to the electrical conductors, as the pins can simply be withdrawn from the openings, and re-inserted as necessary. 
         [0033]    Any given electrical raft may be provided with one or more electrical wires embedded therein (which may be sheathed) and/or one or more flexible printed circuits embedded therein, As such, a given electrical raft may have wires and flexible printed circuits laid therein. 
         [0034]    The electrical raft may have a first major surface from which the connector body is removable. The electrical raft may have a second major surface which is separated by a thickness from the first major surface. The second major surface may be substantially parallel to the first major surface. The electrical conductors embedded in the raft may generally extend in a direction that is substantially parallel to the first and/or second major surface. 
         [0035]    The electrical raft may comprise an earthing (or grounding) mesh. The earthing mesh may be referred to as an electrically conductive screen layer, and may or may not take the form of a mesh. The earthing mesh may provide electrical screening to the electrical conductors embedded in the raft. For example, the earthing mesh may provide electrical screening against electrical interference and/or from electrical surges, for example from lightning strikes. The earthing mesh may be grounded, for example to a gas turbine engine to which the electrical raft may be provided. The earthing mesh may take any suitable form/arrangement. For example, it may be a mesh-type construction (meaning that it may be a surface with holes provided therein) and/or may be metallic. The earthing mesh may be embedded in the rigid material (for example it may be provided during manufacture). Alternatively or additionally, a fixture may be provided to hold the earthing mesh in position. 
         [0036]    The earthing mesh may be connected (electrically and/or mechanically) to a back-shell location formation, where both are present. 
         [0037]    In general, the use of one or more electrical rafts/electrical raft assemblies may significantly reduce build time of an engine. For example, use of electrical rafts/electrical raft assemblies may significantly reduce the part count involved in engine assembly compared with a conventional harness arrangement. The number and/or complexity of the operations required to assemble an engine (for example to assemble/install the electrical system (or network) and/or other peripheral components, which may be referred to in general as engine dressing) may be reduced. For example, rather than having to install/assemble a great number of wires and/or wiring looms together on the engine installation, it may only be necessary to attach a relatively small number of electrical rafts/electrical raft assemblies, which themselves may be straightforward to handle, position, secure and connect. Thus, use of electrical raft assemblies in a gas turbine installation may reduce assembly time and/or reduce the possibility of errors occurring during assembly. 
         [0038]    Use of electrical raft assemblies may provide significant advantages during maintenance, such as repair and overhaul. As discussed above, the electrical rafts may be particularly quick and straightforward to assemble. The same advantages discussed above in relation to assembly apply to disassembly/removal from the gas turbine engine. Thus, any repair/overhaul that requires removal of at least a part of the electrical harness may be simplified and/or speeded up through use of electrical rafts as at least a part of the electrical harness, for example compared with conventional harnesses. Use of electrical rafts (for example as part of one or more electrical raft assemblies) may allow maintenance procedures to be advantageously adapted. For example, some maintenance procedures may only require access to a certain portion of the gas turbine engine that only requires a part of the harness to be removed. It may be difficult and/or time consuming, or not even possible, to only remove the required part of a conventional harness from a gas turbine engine. However, it may be relatively straightforward to only remove the relevant electrical raft, for example by simply disconnecting it from the engine and any other electrical rafts/components to which it is connected. Decreasing maintenance times has the advantage of, for example, reducing out-of service times (for example off-wing times for engines that are used on aircraft). 
         [0039]    The build/assembly times may be additionally or alternatively reduced by pre-assembling and/or pre-testing individual and/or combinations of electrical rafts and/or electrical raft assemblies prior to engine assembly. This may allow the electrical and/or mechanical operation of the electrical rafts to be proven before installation, thereby reducing/eliminating the testing required during engine installation. 
         [0040]    The electrical rafts/electrical raft assemblies may be a particularly lightweight solution for transferring electrical signals around an engine. For example, an electrical raft may be lighter, for example significantly lighter, than a conventional harness required to transmit a given number of electrical signals. A plurality of conductors may be embedded in a single electrical raft, whereas in a conventional arrangement a large number of heavy, bulky wires, usually with insulating sleeves, would be required. The reduced weight may be particularly advantageous, for example, when used on gas turbine engines on aircraft. 
         [0041]    Electrical rafts may be more easily packaged and/or more compact, for example than conventional harnesses. Indeed, as mentioned above, the electrical rafts can be made into a very wide range of shapes as desired. This may be achieved, for example, by manufacturing the electrical rafts using a mould conforming to the desired shape. As such, each electrical raft may be shaped, for example, to turn through a tighter corner (or smaller bend radius) than a conventional harness. The electrical rafts may thus provide a particularly compact solution for transferring electrical signals around a gas turbine engine. The electrical rafts may be readily shaped to conform to neighbouring components/regions of a gas turbine engine, for example components/regions to which the particular electrical raft assembly is attached, such as a fan casing or a core casing. 
         [0042]    The electrical raft(s) may provide improved protection to the electrical conductors during manufacture/assembly of the raft/gas turbine installation, and/or during service/operation/maintenance of the gas turbine engine. This may result in lower maintenance costs, for example due to fewer damaged components requiring replacement/repair and/or due to the possibility of extending time intervals (or service intervals) between inspecting the electrical system, for example compared with a system using only conventional harnesses. 
         [0043]    Any suitable material may be used for the rigid material of the electrical raft. For example, the rigid material may be a rigid composite material, for example an organic matrix composite. Such a rigid composite material may be particularly stiff and/or lightweight. Thus, a rigid composite raft may be used that has suitable mechanical properties, whilst being thin and lightweight, for example compared with some other materials. The rigid composite material may comprise any suitable combination of resin and fibre as desired for a particular application. For example, any of the resins and/or fibres described herein may be used to produce a rigid composite material for the electrical raft. Any suitable fibres may be used, for example carbon fibres, glass fibres, aramid fibres, and/or para-aramid fibres. The fibres may be of any type, such as woven and/or chopped, Any suitable resin may be used, for example epoxy, BMI (bismaleimide), PEEK (polyetheretherketone), PTFE (polytetraflouroethylene), PAEK (polyaryletherketone), polyurethane, and/or polyamides (such as nylon). 
         [0044]    In any example of electrical raft or electrical raft assembly, at least one of the electrical conductors embedded in the electrical raft may be an electrically conductive wire. The or each electrically conductive wire may be surrounded by an electrically insulating sleeve. 
         [0045]    At least some (for example a plurality) of the electrical conductors may be provided in a flexible printed circuit (FPC). Thus, at least some of the electrical conductors may be provided as electrically conductive tracks in a flexible substrate. The flexible printed circuit may be flexible before being embedded in the rigid material. 
         [0046]    Providing the electrical conductors as tracks in a flexible printed circuit may allow the size of the resulting electrical raft to be reduced further and/or substantially minimized. For example, many different electrical conductors may be laid into a flexible printed circuit in close proximity, thereby providing a compact structure. The flexible substrate of a single flexible printed circuit may provide electrical and/or mechanical protection/isolation to a large number of electrical conductors. 
         [0047]    Any given electrical raft may be provided with one or more electrical wires embedded therein (which may be sheathed) and/or one or more flexible printed circuits embedded therein. As such, a given electrical raft may have wires and flexible printed circuits laid therein. 
         [0048]    It will be appreciated that the embedded electrical conductors (whether they are provided as embedded electrical wires or as conductive tracks in a flexible printed circuit embedded in the rigid material) may be described as being fixed in position by the rigid material, for example relative to the rest of the electrical harness raft. It will also be appreciated that the embedded electrical conductors may be said to be surrounded by the rigid material and/or buried in the rigid material and/or integral with (or integrated into) the rigid material. 
         [0049]    The electrical raft (or electrical raft assembly) may be at least a part of an electrical harness for a gas turbine engine, and thus may be referred to herein as an electrical harness raft (or electrical harness raft assembly). 
         [0050]    An electrical raft (or electrical raft assembly) may comprise a fluid passage. Such a fluid passage may be embedded therein and/or otherwise provided thereto. The fluid passage may be part of a fluid system, such as a gas (for example pneumatic or cooling gas/air) and/or liquid (for example a fuel, hydraulic and/or lubricant liquid). 
         [0051]    There is also provided a method of assembling an electrical raft assembly and/or a gas turbine engine, The method comprises preparing an electrical raft assembly as described above and elsewhere herein. The method also comprises electrically and mechanically connecting the prepared electrical raft assembly to the rest of the apparatus/gas turbine engine. 
         [0052]    Thus, there is provided a gas turbine engine or gas turbine engine installation (for example for an airframe) comprising an electrical raft and/or an electrical raft assembly as described above and elsewhere herein. For example, at least one electrical raft and/or electrical raft assembly may be used as part of an electrical harness for transferring electrical signals around the engine, in the form of electrical harness raft(s) and/or electrical harness raft assemblies. 
         [0053]    The electrical raft may comprise one or more electrical connectors (which, as well as the type described above in relation to the first aspect, may be of other type) or sockets, which may be electrically connected to at least one of the embedded electrical conductors. The electrical connector or socket may allow electrical connection of the electrical raft to other electrical components, for example to other electrical rafts (either directly or indirectly, via an electrical cable or lead) or to electrical units (again, either directly or indirectly, via an electrical cable or lead). Such an electrical connector or socket may take any suitable form, and may be at least partially embedded in the rigid electrical raft. 
         [0054]    The electrical raft assembly may be a first engine installation component, and the gas turbine engine may further comprise a second engine installation component having electrical conductors. The gas turbine engine may further comprise at least one flexible cable connected between the electrical raft assembly and the second engine installation component so as to electrically connect electrical conductors of the electrical raft assembly with electrical conductors of the second engine installation component. 
         [0055]    The second engine installation component may be, for example, an ECU, such as an EMU or EEC. Additionally or alternatively, the second engine installation component may be a further electrical raft or electrical raft assembly. 
         [0056]    The environment of a gas turbine engine during operation may be particularly severe, with, for example, high levels of vibration and/or differential expansion between components as the temperature changes through operation and as the components move relative to each other. Providing at least one flexible cable to connect an electrical raft assembly to another component may allow the electrical rafts and/or components to accommodate vibration and/or relative movement, for example of the component(s)/assemblies to which they are attached/mounted during use. For example, the flexible cable(s) (where present) used to electrically connect electrical raft assemblies to other component(s) may have sufficient length to accommodate such vibration and/or movement during use. 
         [0057]    For example, providing separate (for example more than one) electrical raft assemblies and connecting at least some (for example at least two) of them together using at least one flexible cable may allow the electrical rafts to accommodate vibration and/or relative movement of the component(s)/assemblies to which they are attached/mounted during use. 
         [0058]    The electrical signals transferred by the conductors in the electrical raft, and around the engine using the electrical rafts/raft assemblies may take any form. For example, the electrical signals may include, by way of non-limitative example, electrical power and/or electrical control/communication signals and/or any other type of transmission through an electrical conductor. Transmission of signals around the engine may mean transmission of signals between (to and/or from) any number of components/systems in the engine and/or components/system of a structure (such as an airframe) to which the gas turbine engine is (or is configured to be) connected/installed in. In other words, an electrical raft may be used to transfer/communicate any possible combination of electrical signals in any part of a gas turbine engine installation or a related (for example electrically and/or mechanically connected) structure/component/system. 
         [0059]    An electrical raft or raft assembly may be provided in any suitable location/position of the gas turbine engine, for example to a mounting structure at any suitable location. For example, the gas turbine engine may comprise a bypass flow duct formed between an engine core and an engine fan casing (the gas turbine engine may be a turbofan engine, for example); and the electrical raft assembly may form at least a part of a radially extending splitter (which may be referred to as a bifurcation) that extends across the bypass flow duct. In this way, an electrical raft (which may be referred to as a splitter electrical raft) may provide an electrical connection between a fan casing and an engine core. By way of further example, the electrical raft assembly may be attached to the engine core case or engine fan case, for example to a mounting structure on such cases. 
         [0060]    Other components/systems of a gas turbine engine may be provided to an electrical raft assembly in any suitable manner. For example, such other components/systems may be mounted on one or more electrical raft assemblies. Thus, a surface of an electrical harness raft may be used as a mounting surface for other gas turbine engine components/systems, such as ancillary/auxiliary components/systems. 
         [0061]    For example, an electrical unit may be mounted on an electrical raft. The electrical unit may be any sort of electrical unit, for example one that may be provided to a gas turbine engine. For example, the electrical unit may be any type of electronic control unit (ECU), such as an Electronic Engine Controller (EEC) and an Engine Health Monitoring Unit (EMU). At least one (i.e. one or more) electrical unit may be attached to an electrical raft. Such an electrical raft assembly may be a particularly convenient, lightweight and/or compact way of providing (for example attaching, fixing or mounting) an electrical unit to a turbine engine. For example, the electrical unit and the electrical raft may be assembled together (mechanically and/or electrically) before being installed on the gas turbine engine, as described elsewhere herein. 
         [0062]    An electrical raft may be provided with at least one mount on which other components (for example auxiliary/ancillary components/systems) of the gas turbine engine are (or may be) mounted. The mount may be a bracket, for example a bespoke bracket for the component/system mounted thereon or a conventional/standard bracket. The electrical raft may provide a stable, regular and convenient platform on which to mount the various systems/components. The combination of the installed electrical raft assembly with components/systems mounted thereon may be much more compact and/or straightforward to assemble and/or have a greatly reduced number of component parts, for example compared with the corresponding conventional electrical harness and separately mounted components/systems. 
         [0063]    The mounts may be used to attach any component/system to an electrical raft (and thus to the engine) as required. For example, fluid pipes for transferring fluid around the engine may be mounted to the electrical rafts (for example mechanically mounted using a bracket), and thus to the engine. More than one set of fluid pipes, for example for carrying different or the same fluids, may be mounted on the same electrical raft. 
         [0064]    An anti-vibration mount may be used to attach an electrical raft to another component, thereby allowing the electrical raft to be vibration isolated (or at least substantially vibration isolated). Using an anti-vibration mount to attach an electrical raft/assembly to a gas turbine engine for example may reduce (or substantially eliminate) the amount (for example the amplitude and/or the number/range of frequencies) of vibration being passed to the electrical raft from the gas turbine engine, for example during use. This may help to prolong the life of the electrical raft. Furthermore, any other components that may be attached to the electrical raft (as discussed above and elsewhere herein) may also benefit from being mounted to the gas turbine engine via the anti-vibration mounts, through being mounted on the electrical raft. For example, the reduced vibration may help to preserve the electrical contact between the electrical raft and any electrical unit connected thereto. As such, any components (such as an electrical unit mounted to the electrical raft) that would conventionally be mounted directly to the gas turbine engine and require at least a degree of vibration isolation no longer require their own dedicated anti-vibration mount. Thus, the total number of anti-vibration mounts that are required to assemble an engine may be reduced. This may reduce the number of parts required and/or the time taken to assemble an engine or engine installation and/or reduce the total assembled weight and/or reduce the likelihood of errors occurring during assembly. 
         [0065]    Furthermore, components that are conventionally mounted to an engine without anti-vibration mounts (for example because of the weight and/or cost penalty), but which are now mounted to an electrical raft (for example to a mounting surface of the electrical raft), may benefit from vibration isolation without any weight/cost/assembly time penalty. This may reduce the possibility of damage occurring to such components and/or increase their service life. Such components may include, for example, ignitor boxes (used to provide high voltage power to engine ignitors), and pressure sensors/switches, for example for fluid systems such as oil, air, fuel, pneumatics and/or hydraulics. 
         [0066]    Further optional features of the invention are set out below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0067]    Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: 
           [0068]      FIG. 1  shows a gas turbine engine with a conventional harness; 
           [0069]      FIG. 2  shows a cross-section through a gas turbine engine in accordance with the present invention; 
           [0070]      FIG. 3  shows a perspective view of a flexible printed circuit; 
           [0071]      FIG. 4  shows a side view of the flexible printed circuit of  FIG. 3 ; 
           [0072]      FIG. 5  shows a schematic of an electrical raft prior to assembly; 
           [0073]      FIG. 6  shows a cross-section normal to the axial direction through a gas turbine engine in accordance with the present invention; 
           [0074]      FIG. 7  shows a perspective view of a connector; 
           [0075]      FIG. 8  shows an exploded view of the connector of  FIG. 7 ; 
           [0076]      FIG. 9  shows (a) side and (b) end views of the connector of  FIG. 7  located in an electrical raft; 
           [0077]      FIG. 10  shows schematically a plan view of a lollipop connector of a flexible printed circuit board; and 
           [0078]      FIG. 11  shows schematically a cross-section of the connector of  FIG. 7  connected to the lollipop connector of  FIG. 10 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0079]    With reference to  FIG. 2 , a ducted fan gas turbine engine generally indicated at  10  has a principal and rotational axis X-X. The engine  10  comprises, in axial flow series, an air intake  11 , a propulsive fan  12 , an intermediate pressure compressor  13 , a high-pressure compressor  14 , combustion equipment  15 , a high-pressure turbine  16 , and intermediate pressure turbine  17 , a low-pressure turbine  18  and a core engine exhaust nozzle  19 . The engine also has a bypass duct  22  and a bypass exhaust nozzle  23 . 
         [0080]    The gas turbine engine  10  works in a conventional manner so that air entering the intake  11  is accelerated by the fan  12  to produce two air flows: a first air flow A into the intermediate pressure compressor  13  and a second air flow B which passes through the bypass duct  22  to provide propulsive thrust, The intermediate pressure compressor  13  compresses the air flow A directed into it before delivering that air to the high pressure compressor  14  where further compression takes place. 
         [0081]    The compressed air exhausted from the high-pressure compressor  14  is directed into the combustion equipment  15  where it is mixed with fuel and the mixture combusted. The resultant hot combustion products then expand through, and thereby drive the high, intermediate and low-pressure turbines  16 ,  17 ,  18  before being exhausted through the nozzle  19  to provide additional propulsive thrust. The high, intermediate and low-pressure turbines  16 ,  17 ,  18  respectively drive the high and intermediate pressure compressors  14 ,  13  and the fan  12  by suitable interconnecting shafts. 
         [0082]    The gas turbine engine  10  shown in  FIG. 2  shows two electrical raft assemblies  600  according to the invention. As such, the gas turbine engine  10  is in accordance with the present invention. Each electrical raft assembly  600  comprises an electrical raft  200 . The electrical rafts  200  may be used to transmit/transfer electrical signals (or electricity, including electrical power and/or electrical control signals) around the engine and/or to/from the engine  10  from other components, such as components of an airframe. The function and/or construction of each electrical raft  200  and electrical raft assembly  600  may be as described above and elsewhere herein. 
         [0083]    In  FIG. 2 , each electrical raft  200  (which may be referred to herein simply as a raft  200  or an electrical harness raft  200 ) comprises at least one electrical conductor  252  embedded in a rigid material  220 , which may be a rigid composite material. 
         [0084]    The electrical conductors  252  in the electrical raft  200  may be provided in a harness  250 , which may be a flexible printed circuit board (or FPC)  250 . 
         [0085]    An example of an FPC  250  in which the electrical conductors  252  may be provided is shown in greater detail in  FIGS. 3 and 4 .  FIG. 3  shows a perspective view of the FPC  250 , and  FIG. 4  shows a side view. 
         [0086]    Such an FPC  250  may comprise a flexible (for example elastically deformable) substrate  255  with conductive tracks  252  laid/formed therein. The FPC  250  may thus be deformable. The FPC  250  may be described as a thin, elongate member and/or as a sheet-like member. Such a thin, elongate member may have a major surface defined by a length and a width, and a thickness normal to the major surface. In the example shown in  FIGS. 3 and 4 , the FPC  250  may extend along a length in the x-direction, a width in the y-direction, and a thickness (or depth or height) in the z-direction. The x-direction may be defined as the axial direction of the FPC. Thus, the x-direction (and thus the z-direction) may change along the length of the FPC  250  as the FPC is deformed, This is illustrated in  FIG. 4 . The x-y surface(s) (i.e. the surfaces formed by the x and y directions) may be said to be the major surface(s) of the FPC  250 . In the example shown in  FIGS. 3 and 3 , the FPC  250  is deformable at least in the z direction, i.e. in a direction perpendicular to the major surface. FPCs may be additionally of alternatively deformable about any other direction, and/or may be twisted about any one or more of the x, y, or z directions. 
         [0087]    The flexible substrate  255  may be a dielectric. The substrate material may be, by way of example only, polyamide. As will be readily apparent, other suitable substrate material could alternatively be used. 
         [0088]    The conductive tracks  252 , which may be surrounded by the substrate  255 , may be formed using any suitable conductive material, such as, by way of example only, copper, copper alloy, tin-plated copper (or tin-plated copper alloy), silver-plated copper (or silver-plated copper alloy), nickel-plated copper (or nickel-plated copper alloy) although other materials could alternatively be used. The conductive tracks  252  may be used to conduct/transfer electrical signals (including electrical power and electrical control signals) through the rigid raft assembly (or assemblies)  200 , for example around a gas turbine engine  10  and/or to/from components of a gas turbine engine and/or an airframe attached to a gas turbine engine. 
         [0089]    The size (for example the cross-sectional area) and/or the shape of the conductive tracks  252  may depend on the signal(s) to be transmitted through the particular conductive track  252 . Thus, the shape and/or size of the individual conductive tracks  252  may or may not be uniform in a FPC  250 . 
         [0090]    The example shown in  FIGS. 3 and 4  has six conductive tracks  252  running through the substrate  255 . However, the number of conductive tracks  252  running through a substrate  255  could be fewer than six, or greater than six, for example tens or hundreds of tracks, as required. As such, many electrical signals and/or power transmission lines may be incorporated into a single FPC  250 . 
         [0091]    A single FPC  250  may comprise one layer of tracks, or more than one layer of tracks, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more than 10 layers of tracks. An FPC may comprise significantly more than 10 layers of tracks, for example at least an order of magnitude more layers of tracks, In this regard, a layer of tracks may be defined as being a series of tracks that extend in the same x-y surface. Thus, the example shown in  FIGS. 3 and 4  comprises 2 layers of tracks, with each layer comprising 3 tracks  252 . 
         [0092]    An electrical raft  200  may be manufactured using any suitable method. For example, the rigid material  220  may initially be provided as layers of flexible material, such as (by way of example only) layers of fibre and resin compound. This flexible material may be placed into a mould, for example having a desired shape. Other components (such as fluid pipes  210  and/or the electrical conductors  252 , which may be embedded in a FPC  250 ) may also be placed into the mould, for example between layers of the flexible material from which the rigid material  220  is ultimately formed. Parts of the mould may have any suitable form and/or construction, for example that could be readily removed when the electrical raft  200  is formed into the desired shape. 
         [0093]      FIG. 5  shows components of an example of an electrical raft  200  prior to one method of construction. The electrical conductors  252  are provided between two layers of material  230 ,  240  that, after construction, form the rigid material  220 . Some of the electrical conductors  252  are provided in an FPC  250 . The material  230 ,  240  may be a fibre and resin compound, as described elsewhere herein. Such a fibre and resin compound may, after suitable treatment (for example heat treatment), produce the rigid composite material  220 . In the example of  FIG. 5 , the fibre and resin compound is formed of a sheet of interwoven fibres, or strands. The strands in  FIG. 5  extend in perpendicular directions, although the strands may extend in any one or more directions as required. The strands/fibres may be pre-impregnated (or “pre-pregged”) with the resin. 
         [0094]    Prior to any treatment, both the first and second layers  230 ,  240  and the electrical conductors  252  may be flexible, for example supple, pliable or malleable. As such, when the layers  230 ,  240  and the electrical conductors  252  are placed together, they may be moulded, or formed, into any desired shape. For example, the layers  230 ,  240  and the electrical conductors  252  may be placed into a mould (which may be of any suitable form, such as a glass or an aluminium mould) having the desired shape. The desired shape may be, for example, a shape that corresponds to (for example is offset from) a part of a gas turbine engine, such as, by way of example only, at least a part of a casing, such as an engine fan casing or engine core casing. This may enable the final raft to adopt shapes that are curved in two-dimensions or three-dimensions. 
         [0095]    Any suitable method could be used to produce the electrical raft  200 . For example, the strands/fibres need not be pre-impregnated with the resin. Instead, the fibres/strands could be put into position (for example relative to electrical conductors  252 /FPC  250 ) in a dry state, and then the resin could be fed (or pumped) into the mould. Such a process may be referred to as a resin transfer method. In some constructions no fibre may be used at all in the rigid material  220 . 
         [0096]      FIG. 6  is a schematic showing a cross-section perpendicular to the direction X-X of a gas turbine engine comprising electrical raft assemblies  600 A- 600 G. Any one of the electrical raft assemblies  600 A- 600 G may comprise any or all of the features of an electrical raft assembly  600  as described herein, for example. Thus, for example, any one of the electrical raft assemblies may comprise an electrical raft  200  (not labelled for raft assemblies  600 E- 600 G for simplicity only) having electrical conductors  252  (not labelled in  FIG. 6  for simplicity only) embedded therein. Some or all of the electrical raft assemblies  600 A- 600 G (which may collectively be referred to as electrical raft assemblies  600 ) comprise a mounting fixture for attaching the respective assembly  600  to a mounting structure  700  (such as an anti-vibration mount). 
         [0097]    The mounting structure is part of a fan case  24  for electrical raft assemblies  600 A- 600 G, part of a bifurcation splitter that radially crosses a bypass duct  22  for electrical raft assemblies  600 E and part of an engine core case  28  for electrical raft assemblies  600 F and  600 G. However, it will be appreciated that an electrical raft assembly  600  could be mounted in any suitable and/or desired location on a gas turbine engine. 
         [0098]    In  FIG. 6 , two electrical raft assemblies  600 A,  600 C are shown as having an electrical unit  300  mounted on the respective electrical raft  200 . However, any (or none) of the electrical raft assemblies  600 A- 600 G may have an electrical unit  300  mounted to the respective electrical raft  200 . 
         [0099]    As mentioned herein, each of the electrical rafts  200  associated with the electrical raft assemblies  600 A- 600 G shown in  FIG. 6  comprises one or more electrical conductors  252  embedded therein. However, any one or more of the electrical rafts  200  may be replaced with a raft that does not comprise electrical conductors  252 . Such a raft would not be an electrical raft  200 , but may otherwise be as described elsewhere herein, for example it may be a rigid raft that may have components/systems (such as, by way of example only, fluid systems, such as pipes) mounted thereon and/or embedded therein. Thus, for example, a gas turbine engine in accordance with the present invention may have a combination of electrical rafts  200  and non-electrical rafts. 
         [0100]    The arrangement of electrical raft assemblies  600 A- 600 G shown in  FIG. 6  is by way of example only. Alternative arrangements, for example in terms of number, size, shape and/or positioning, of electrical raft assemblies  600 A- 600 G may be used. For example, there need not be seven electrical raft assemblies, the assemblies may or may not be connected together, and the rafts could be provided to (for example mounted on) any one or more components of the gas turbine engine. Purely by way of example only, connection between electrical raft assemblies  600 A- 600 D mounted on the fan casing  24  to the electrical raft assemblies  600 F,  600 G mounted on the core casing  28  may be provided at least in part by means other than an additional electrical raft assembly  600 E, for example using wire conductors with insulating sleeves. By way of further example, one or more electrical raft assemblies  600  may additionally or alternatively be provided to the nose cone, structural frames or elements within the engine (such as “A-frames”), the nacelle, the fan cowl doors, and/or any connector or mount between the gas turbine engine  10  and a connected structure (which may be at least a part of a structure in which the gas turbine engine  10  is installed), such as the pylon  500  between the gas turbine engine  10  and an airframe (not shown). 
         [0101]    Any one or more of the electrical rafts of the electrical raft assemblies  600 A- 600 G may have a fluid passage  210  embedded therein and/or provided thereto. The fluid passage  210  may be part of a fluid system, such as a gas (for example pneumatic or cooling gas/air) and/or liquid (for example a fuel, hydraulic and/or lubricant liquid). In the  FIG. 6  example, three of the electrical rafts (of electrical raft assemblies  600 A,  600 B,  600 C) comprise a fluid passage  210  at least partially embedded therein. The electrical raft of assembly  600 C also has a fluid passage  285  (which may be for any fluid, such as those listed above in relation to embedded passage  210 ) mounted thereon. Such a mounted fluid passage  285  may be provided to any electrical raft, such as those of electrical raft assemblies  600 A- 600 G shown in  FIG. 6 . The fluid passages  210 ,  285  shown in  FIG. 6  may be oriented in an axial direction of the engine  10 . However, fluid passages may be oriented in any direction, for example axial, radial, circumferential or a combination thereof. 
         [0102]    Any of the electrical raft assemblies  600 A- 600 G (or the respective electrical rafts  200  thereof) may have any combination of mechanical, electrical and/or fluid connections to one or more (for example 2, 3, 4, 5 or more than 5) other components/systems of the gas turbine engine  10  and/or the rest of the gas turbine engine  10 . Examples of such connections are shown in  FIG. 6 , and described below, but other connectors may be used. For example, electrical raft assemblies  600  (and/or non-electrical rafts) may be connected together (or to other components) using any combination of electrical, fluid and/or mechanical connectors. Thus, any of the connections  290 A/ 290 B,  291 - 297  shown in  FIG. 6  may be any combination of electrical, fluid and/or mechanical connection. Alternatively, electrical raft assemblies  600  (and/or non-electrical rafts) may be standalone, and thus may have no connection to other rafts or components. 
         [0103]    A connection  291  is shown between the electrical rafts of the assemblies  600 A and  600 D. The connection  291  may comprise an electrical connection. Such an electrical connection may be flexible and may, for example, take the form of a flexible printed circuit such as the flexible printed circuit  250  shown in  FIGS. 3 and 4 . Such a flexible electrical connection may be used to electrically connect any electrical raft assembly  600  to any other component, such as another electrical raft assembly  600 . A connection  297  (which may be or comprise an electrical connection) is provided between the electrical raft of the assembly  600 A and a part of an airframe, or airframe installation  500 , which may, for example, be a pylon. Similarly, a fluid and/or mechanical connection  296  may additionally or alternatively be provided between the airframe  500  and another electrical raft of the assembly  600 C. As shown in  FIG. 6 , other electrical and/or fluid connections  292 ,  293 ,  294 ,  295  may be provided between electrical rafts  200  (or assemblies  600 ) and other components, such as other electrical rafts  200  (or assemblies  600 ). 
         [0104]    A direct connection  290 A,  290 B may be provided, as shown for example between the electrical rafts of the assemblies  600 B and  600 C in the  FIG. 6  arrangement. Such a direct connection  290 A,  290 B may comprise a connector  290 A provided on (for example embedded in) one electrical raft  200  connected to a complimentary connector  290 B provided on (for example embedded in) another electrical raft  200 . Such a direct connection  290 A,  290 B may, for example, provide fluid and/or electrical connection between the two electrical rafts assemblies  600 B,  600 C. 
         [0105]    An electrical raft  200  may have an electrically conductive grounding or screen layer  260 , as shown in the electrical rafts  200  shown in  FIG. 6  (and indeed in  FIG. 2 ). However, it will be appreciated that electrical rafts  200  according to the invention and/or for use with the invention need not have such an electrically conductive grounding or screen layer  260 . Where an electrically conductive grounding or screen layer  260  is present, an electrically conductive fastener  310  may be used to fasten, or fix, the electrical unit  300  (where present) to the electrical raft  200 . This may allow the electrical unit  300  to be electrically grounded. It will also be appreciated, however, that electrical rafts  200  according to the invention and/or for use with the invention need not have such an electrically conductive fastener  310 . 
         [0106]    Where reference is made herein to a gas turbine engine, it will be appreciated that this term may include a gas turbine engine/gas turbine engine installation and optionally any peripheral components to which the gas turbine engine may be connected to or interact with and/or any connections/interfaces with surrounding components, which may include, for example, an airframe and/or components thereof. Such connections with an airframe, which are encompassed by the term “gas turbine engine” as used herein, include, but are not limited to, pylons and mountings and their respective connections. The gas turbine engine itself may be any type of gas turbine engine, including, but not limited to, a turbofan (bypass) gas turbine engine, turbojet, turboprop, ramjet, scramjet or open rotor gas turbine engine, and for any application, for example aircraft, industrial, and marine application. Electrical raft assemblies  600  such as any of those described and/or claimed herein may be used as part of any apparatus, such as any vehicle, including land, sea, air and space vehicles, such as motor vehicles (including cars and busses), trains, boats, submarines, aircraft (including aeroplanes and helicopters) and spacecraft (including satellites and launch vehicles). 
         [0107]    It will be appreciated that many alternative configurations and/or arrangements of electrical raft assemblies  600  and gas turbine engines  10  comprising electrical raft assemblies  600  other than those described herein may fall within the scope of the invention. For example, alternative arrangements of electrical raft assemblies  600  (for example in terms of the arrangement, including number/shape/positioning/constructions, of mounting fixtures, the arrangement/shape/positioning/construction of the electrical rafts  200 , the type and/or positioning of components (if any) mounted to/embedded in the electrical rafts  200 , the rigid material  220  and the electrical conductors  252 ) may fall within the scope of the invention and may be readily apparent to the skilled person from the disclosure provided herein. Alternative arrangements of connections (for example mechanical, electrical and/or fluid) between the electrical (or non-electrical) rafts and/or raft assemblies and between the electrical (or non-electrical) rafts or raft assemblies and other components may fall within the scope of the invention and may be readily apparent to the skilled person from the disclosure provided herein. Furthermore, any feature described and/or claimed herein may be combined with any other compatible feature described in relation to the same or another embodiment. 
         [0108]    The electrical rafts may have electrical connectors for making connections to their electrical conductors, and thereby electrically connecting the rafts with other rafts or electrical units.  FIGS. 7 and 8  show respectively perspective and exploded views of such a connector  700 , and  FIG. 9  shows (a) side and (b) end views of the connector  700  located in the rigid composite material  220  of an electrical raft  200 . Electrical conductors  252  in the form of one or more FPCs  250  are embedded in the raft  200  and extend substantially parallel to first  200   a  and second  200   b  major surfaces of the raft. 
         [0109]    As shown in  FIG. 9(   a ) the electrical raft  200  may also comprise an earthing mesh  770 . The earthing mesh  770  may provide electrical screening to the electrical conductors  252  embedded in the raft. The earthing mesh may be embedded in the composite structure (for example it may be provided during manufacture). 
         [0110]    The electrical connector  700  has a connector body  710  including a housing  706 , a first set of electrical contacts (not shown in  FIGS. 7 to 9 , but discussed below in relation to  FIGS. 10 and 11 ), and a second set of electrical contacts  720 . The housing  706  may contain internal components of the electrical connector  700 , such as internal electrical connections (not shown). The housing  706  has a first end  702  and a second end  704 , which may be opposite to each other. The first set of electrical contacts is formed at the first end  702 . The second set of electrical contacts  720  is formed at the second end  704 . The second end  704  is accessible from outside the electrical raft  200 . 
         [0111]    The embedded electrical conductors  252  are electrically connected to the electrical connector  700  through the first set of electrical contacts. These may take any suitable form, but are disconnectable from the electrical conductors  252 , as discussed in more detail below in relation to  FIGS. 10 and 11 . 
         [0112]    The second set of electrical contacts  720  may also take any suitable form, and may be e.g. as male or female connectors. The second set of electrical contacts  720  electrically connects the electrical connector  700 , and thus the conductors  252  in the electrical raft  200 , to a further electrical component (not shown). 
         [0113]    In the example of  FIGS. 7 to 9 , the second set of electrical contacts  720  are male pins accommodated in a socket formed by the second end  704  of the housing  706  and the complimentary set of contacts are female pins (not shown) accommodated in a plug of the further electrical component. Separate mechanical connectors (not shown) may be provided to hold, or lock, the electrical connector  700  and the further electrical component together, e.g. a locking ring may thread onto thread  705  formed around the second end  704 . 
         [0114]    The further electrical component may take any suitable form. For example, the further electrical component may comprise a set of electrical conductors, such as an FPC, and/or one or more wires, which may be sheathed and/or bundled together. The set of electrical conductors may be used, for example, to connect the electrical raft  200  to another electrical component, which may be, for example, another electrical raft  200  or an ECU, such as an EEC or EMU. 
         [0115]    Alternatively, as mentioned elsewhere herein, the further electrical component may be any type of electrical component. For example, the further electrical component may be an electrical unit, or ECU, such as an EEC or an EMU. Thus, the further electrical component may be an electrical unit, which may be connected to the electrical raft  200 , for example directly connected to the second set of electrical contacts  720  using the set of complimentary electrical contacts. 
         [0116]    The electrical connector  700  also has a back-shell  740  which encloses the first end  702  of the housing  706 . As best shown in  FIG. 8 , the back-shell  740  in the example shown has a base portion  740   a,  a flange portion  740   b,  and a mounting portion  740   c  for the connector body  701 . The flange portion  740   b  and the mounting portion  740   c  both have central through-holes, while the base portion  740   a  has a central blind-hole. The portions are nested with the holes in alignment, and with the flange portion  740   b  sandwiched between the base portion  740   a  and the mounting portion  740   c.  The mounting portion  740   c  has a threaded lower half which screws onto corresponding threaded formed in the blind-hole of the base portion  740   a  to hold the nested portions together. The earthing mesh  770 , where present, may be secured between the nested portions. 
         [0117]    The back-shell  740  is embedded in the rigid material  220  with the mounting portion  740   c  at the first major surface  200   a  of the raft  200 . The aligned holes of the back-shell produce a recess accessible from the major surface  200   a  into which the connector body  710  can be mounted. In this way, the back-shell  740  defines the position of the connector  700  relative to the raft  200 , and can provide sealing against ingress of fluids (such as water, oil and fuel) into the connector  700  during use. 
         [0118]    Elastomeric seals (not shown) may be provided between the components of the back-shell  740  and/or between the back-shell and the connector body  710  to improve the sealing between these components. 
         [0119]    The housing  706  and the back-shell  740  may be electrically conductive and may be in electrical contact with each other to provide electro-magnetic shielding of the connector  700 . For example, the housing and the back-shell can be formed of metal. However another option is to form the housing and the back-shell of conductive or plated composite, plastic or ceramic. 
         [0120]    To manufacture the electrical raft  200 , the electrical conductors  252  (e.g. in the form of one or more FPCs  250 ) may be provided between fibre reinforcement layers that are impregnated with and joined together by a polymer matrix (i.e. resin). Preferably, the back-shell  740  is embedded in this composite material  220  before the polymer matrix is cured or set, e.g. as part of a laying up process of the electrical conductors  252  and reinforcement layers, or before injection moulding of the composite material around the electrical conductors  252  and back-shell  740 . In this way, the back-shell  740  can be integrated with the raft  200 . 
         [0121]    As shown in the Figures, the back-shell may comprise one or more location features. In particular, the base portion  740   a  and the flange portion  740   b  extend radially outwardly beyond the mounting portion  740   c  and prevent the back-shell from being pulled out of the raft  200  through the first major surface  200   a.  Further, the base portion  740   a  has flats  741  which prevent the back-shell from rotating in the raft. 
         [0122]    As shown in  FIG. 10 , an FPC  250  for connection to the connector  700  has electrical conductors  252  which are in the form of tracks in a flexible substrate  255 . The substrate terminates in a dedicated connector  280 , which is then connected to the first set of electrical contacts of the connector  700 . Such a dedicated connector  280 , which may be referred to as a lollipop connector, comprises openings  265 . Each opening  265  is formed at the end of a respective track  252  of the FPC  250 . The openings  265  are internally plated with an electrically conductive layer and are configured to receive the first set of electrical contacts. For example the first set of electrical contacts may comprise pins  718  (as shown in  FIG. 11 ), each of which is received in a respective opening  265 . The lollipop connector  280  may be substantially rigid such that it maintains its shape under operating and/or manufacture loads. This may be achieved, for example, by reinforcing the dedicated connector with a rigid material. 
         [0123]    On manufacture of the electrical raft  200 , the back-shell  740  and the FPC  250  may be arranged such that the lollipop connector  280  is situated in the recess of the back-shell. The flange portion  740   b  has a side channel  742  and the mounting portion  740   c  has a side entry-hole  743  that allow the FPC  250  to enter through the side of the back-shell  740 . Fixing screws or other fasteners (not shown) may be used to retain the lollipop connector  280  in position in the back-shell  740 . 
         [0124]    To mount the connector body  710  to the back-shell  740 , the first end  702  of the housing  706  is presented to the recess of the back-shell  740  such that the first set of electrical contacts  718  insert into the openings  265  of the lollipop connector  280 . A flange  744  around the first end  702  locates the housing  706  in a corresponding groove  745  formed in the outwardly-facing side of the mounting portion  740   c.  A plurality of bolts  746  distributed around the flange  744 , and accessible from outside the raft  200 , then secure the connector body  710  and the back-shell  740  together. Conveniently, the press fit connection of the first set of electrical contacts  718  into the openings  265  avoids permanent joining (e.g. by soldering or mechanical crimping). 
         [0125]    To detach the connector body  710  from the raft  200 , it is a simple matter to undo the screws  746  and pull the connector body away from the raft so that the first set of electrical contacts  718  withdraw from the openings  265 . If fasteners are used to retain the lollipop connector  280  in position in the back-shell  740 , these can help to resist any frictional forces tending to also pull the lollipop connector out of the back-shell. The detached connector body  710  can be replaced, upgraded, repaired etc. as needed. 
         [0126]    While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.