Abstract:
A gas turbine engine installation is provided that has a plurality of flexible printed circuit board (FPCB) harnesses to transfer electrical signals, including electrical power, around a gas turbine engine. The plurality of FPCB harnesses is held to the gas turbine engine installation using clips that have at least two jaws. Each jaw has two sets of opposing teeth that do not intermesh, and cannot intermesh when pushed together. This allows more than one FPCB harness to be held by one clip without the risk of damaging the FPCB harnesses. Preventing the teeth from intermeshing also allows subsequent FPCB harnesses to be inserted into the clip without undue difficulty even after a first FPCB harness has already been inserted.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based upon and claims the benefit of priority from British Patent Application Number 1119037.8 filed 4 Nov. 2011, the entire contents of which are incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to a network for distributing signals and power around a gas turbine engine using a flexible harness. In particular, this invention relates to clips for holding a flexible harness for 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, are commonly transmitted along conductors. Conventionally, such conductors may be in the form of wires and 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. The connections between the individual components and the conventional harness are made, for example, by multi-pin plug and socket connectors. Similarly, communication between the harness and power, control and signalling circuitry is achieved through a multi-pin connector. 
         [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 accommodated within the airframe of an aircraft in which the engine is installed. 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. 
         [0008]    Each conventional harness  102 ,  104  therefore comprises a multitude of insulated wires and cables. This makes the conventional harness bulky, heavy and difficult to manipulate. It is desirable to reduce the size and weight of components on gas turbine engines, particularly, for example, gas turbine engines for use on vehicles, such as aircraft. 
         [0009]    It is proposed to replace at least a portion of, for example all of, the conventional harness with a flexible printed circuit board harness (FPCB harness). An example of a portion of such a flexible printed circuit board harness  20  is shown in  FIGS. 2 to 5 .  FIG. 2  shows a perspective view of the FPCB harness portion, and  FIGS. 3 ,  4 , and  5  show side, top, and cross-sectional views respectively. 
         [0010]    Such an FPCB harness  20  may comprise a flexible (for example elastically deformable) substrate  40  with conductive tracks  30  laid/formed therein. The FPCB harness  20  may thus be deformable. In the example shown in  FIGS. 2 to 5 , the FPCB harness  20  extends 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 FPCB harness. Thus, the x-direction (and thus the z-direction) may change along the length of the FPCB harness  20  as the FPCB harness is deformed. This is illustrated in  FIG. 3 . The x-y surface(s) may be said to be the major surface(s) of the FPCB harness. In the example shown in  FIGS. 2 to 5 , the FPCB harness is deformable in the z direction. i.e. in a direction perpendicular to the major surface. FPCB harnesses 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. 
         [0011]    The flexible substrate  40  may be a dielectric. By way of example, the substrate material may be, by way of example only, polyamide. As will be readily apparent, other suitable substrate material could alternatively be used. 
         [0012]    The conductive tracks  30 , which may be surrounded by the substrate, may be formed using any suitable conductive material, such as, by way of example only, copper, although other materials could alternatively be used. The conductive tracks  30  may be used to conduct/transfer electrical signals and/or electrical power, for example around a gas turbine engine and/or to/from components of a gas turbine engine and/or an airframe attached to a gas turbine engine. The size (for example the cross-sectional area) and/or the shape of the conductive tracks  30  may depend on the signal to be transmitted through the particular conductive track  30 . Thus, the shape and/or size of the individual conductive tracks  30  may or may not be uniform in a FPCB harness  20 . 
         [0013]    The example shown in  FIGS. 2 to 5  has 6 conductive tracks  30  running through the substrate  40 . However, the number of conductive tracks  30  running through a substrate  40  could be fewer than 6, or greater than 6. Indeed the number of conductive tracks  30  could be far greater than 6, 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 FPCB harness. 
         [0014]    A single FPCB harness  20  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 FPCB harness 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. 2 to 5  comprises 2 layers of tracks  30 , with each layer comprising 3 tracks. 
         [0015]    Using an FPCB harness to transmit electrical signals and/or power is therefore advantageous over a conventional harness, for example because of its reduced size, weight and/or complexity. 
         [0016]    In order to attach a harness to a component (for example to a gas turbine engine or related airframe), a clip is required. An example of a clip that may be used to attach a conventional harness to a gas turbine engine is shown in  FIG. 7 . The clip  50  shown in  FIG. 7  is configured to hold a cable, or a bundle of cables which form at least a part of a conventional wire cable harness. The clip  50  has a generally cylindrical outer casing  52  with a diameter  56  and a structural internal element  54  configured to provide strength to the clip  50 . The clip  50  shown in  FIG. 7  also has teeth  56  configured to grasp the generally cylindrical conventional cable harness, although the teeth  56  may not be present in some conventional clips. 
         [0017]      FIGS. 8 and 9  show an alternative clip  60  for holding a conventional cable harness. The clip  60  shown in  FIGS. 8 and 9  comprises two arms  64 ,  66  that define a space  62  therebetween for holding a conventional cable harness or bundle of cable harnesses. The space  62  defined between the two arms  64 ,  66  may be generally cylindrical. The two arms  64 ,  66  are sprung so as to be able to accommodate various diameters of conventional cable harnesses. 
       OBJECTS AND SUMMARY OF THE INVENTION 
       [0018]    FPCB harnesses have properties that present difficulties when considering how to attach them to components, for example of a gas turbine engine. For example, the FPCB harnesses may have mechanical properties that mean that known clips, such as those described above, are not suitable for attaching them to components. Purely by way of example only, the flexible substrate material may be relatively easily damaged (for example punctured or sliced) by conventional clips. 
         [0019]    As explained herein, FPCB harnesses offer considerable advantages over conventional harness in terms of, amongst other things, size and weight. It is desirable to maximize this size/weight benefit by providing an attachment device for allowing the FPCB harnesses to be connected to components in a compact, efficient manner. Conventional clips are therefore not desirable, or even suitable. 
         [0020]    According to the an aspect of the invention, there is provided a gas turbine engine installation comprising at least two flexible printed circuit board harnesses arranged to transfer electrical signals around the engine installation, and at least one clip holding at least two flexible printed circuit board harnesses. Each clip comprises a first jaw and a second jaw that hold respective first and second flexible printed circuit board harnesses. The first and second jaws each comprise a set of directly opposing, non-overlapping, compliant teeth arranged to grip the respective harness. 
         [0021]    The electrical signals can be of any type that may be transmitted along electrical conductors, for example electrical power transmission, and/or signals (for example control signals) to, from or between components (for example electrical components) of the gas turbine engine installation. The FPCB harnesses for transmitting the electrical signals may be as described herein, for example with reference to  FIGS. 2 to 5 . 
         [0022]    Because the sets of teeth in each jaw are directly opposing, their tips may not intermesh if the sets of teeth are pushed together. Instead, if the sets of teeth are pushed together (i.e. opposing teeth are moved towards each other), the tips of the opposing teeth may come into contact with each other, but cannot move past each other. As such, this arrangement of teeth means that the opposing teeth in a jaw cannot overlap (i.e. the tips of the upper set of teeth cannot move past than the tips of the lower set of teeth and vice versa), and thus cannot intermesh when pushed together. 
         [0023]    An advantage of this arrangement of teeth in the jaws is that once the first flexible printed circuit board harness has been pushed into the first jaw and gripped by the respective teeth, the teeth of the second jaw do not (indeed cannot) intermesh. This means that the second flexible printed circuit board harness can be inserted into the second jaw even if the first flexible printed circuit board harness has already been inserted into the first jaw, because the teeth of the second jaw remain non intermeshed at all times. If the teeth of the second jaw were to intermesh, it would be extremely difficult, or even impossible, to insert the second flexible printed circuit board harness into the second jaw. 
         [0024]    A further advantage of arranging the teeth to be directly opposing, non-overlapping and compliant is that it enables the respective FPCB harness to be appropriately gripped, whilst reducing (or substantially eliminating) the possibility of damage to the FPCB harness. For example, by avoiding the possibility of opposing teeth intermeshing, the FPCB harness can remain substantially flat within the jaw (for example without containing regions of high curvature), thereby reducing the possibility of damage, such a splitting or fretting, to the FPCB harness. 
         [0025]    The invention provides a method of assembling a gas turbine engine installation. The method comprises providing at least two flexible printed circuit board harnesses arranged to transfer electrical signals (which, as explained above, may be of any type) around the engine installation. The method comprises attaching a first flexible printed circuit board harness to the rest of the gas turbine engine installation by inserting a portion thereof into a first jaw provided in a dip. The method comprises attaching a second flexible printed circuit board harness to the rest of the gas turbine engine installation, after attaching the first flexible printed circuit board harness, by inserting a portion thereof into a second jaw provided in the dip. Each jaw comprises a set of directly opposing, non-overlapping, compliant teeth, such that before and during the step of attaching the second flexible printed circuit board harness, the opposing teeth of the second jaw are not intermeshed. 
         [0026]    This method provides various advantages, including those outlined above and elsewhere herein in relation to the gas turbine engine installation. 
         [0027]    A gap may be provided between directly opposing teeth. Such a gap may be provided when the jaw is in an undeformed state, for example when no external forces are applied to it. The gap may be set to facilitate insertion of the FPCB into the jaw, whist providing sufficient grip to hold the FPCB in use. The gap may depend on the thickness of the FPCB harness intended to be inserted into the jaw. The gap may be set to allow FPCB harnesses with a range of thicknesses to be inserted. 
         [0028]    The gap may be in the range of from 0.1 mm to 10 mm, for example 0.5 mm to 5 mm, for example 1 mm to 4 mm, for example 2 mm to 3 mm, for example on the order of 2.5 mm. In alternative arrangements, there may be no gap between opposing teeth in a jaw in the undeformed state. This may be particularly suitable for holding particularly thin FPCB harnesses. 
         [0029]    The tips of (some or all of) the teeth may be blunt. This may mean that the tips of the teeth may not be sharp, or not pointed. It may mean that the tips of the teeth do not have an apex. Thus, the tips of the teeth may be squared off, i.e. the parts of opposing teeth that face each other may be flat surfaces, which may be parallel. The tips of the teeth may take other suitable shapes, such as a rounded shape. 
         [0030]    Having blunt tips may help to reduce the pressure applied to the FPCB harness when it is gripped by the teeth. This may help to reduce, or substantially eliminate, the possibility of damage to the FPCB harness when it is gripped. 
         [0031]    At least one of the first and second jaws may be formed using a material comprising one or more of ethylene-propylene rubber, a silicone based compound, and a nitrile material. These materials may provide good grip to a FPCB harness whilst being compliant so as to minimize the possibility of damage to the FPCB harness. The particular material may be chosen depending on the application, for example the environment (for example in terms of temperature variation) in which the clip is to be used and/or the type of FPCB harness it is to be used with. 
         [0032]    At least one clip (for example all clips) may further comprise a support structure configured to resist changes in shape of the clip under operational loads. The support structure may be relatively more stiff than the jaws. As such, the support structure may help to reduce, or substantially prevent flexing of the clip, for example flexing of the external shape of the clip. This may help to ensure that the jaws retain the desired shape under load, for example it may help to ensure that the jaws don&#39;t flex apart more than a desired amount when a FPCB harness is inserted. This may help to ensure that the FPCB harnesses are clamped with the desired force. 
         [0033]    The clip may comprise a main body that may incorporate the jaws. The main body may thus be integral with the jaws and, for example, manufactured from the same material and/or using the same process as the jaws. The support structure may extend around at least a part of the main body. This may be a convenient arrangement for providing structural support to the clip. 
         [0034]    The support structure may be formed using a material comprising metal and/or a composite/fibre resin. The support structure may thus be constructed using a material that is more stiff than the main body and/or the jaws of the clip. This may allow the clip to be structurally stiff, whilst retaining compliant teeth for gripping the FPCB harness. 
         [0035]    The support structure may further comprise an attachment portion used to attach the clip to the gas turbine engine, or a component thereof. Thus, the clip can be particularly compact, with a minimal number of parts required to attach it (and thus a FPCB harness) to a component. This may have further weight and/or size benefits. 
         [0036]    Each flexible printed circuit board harness may be described as a thin, elongate 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. The teeth of the clip may thus contact, and grip, the major surface (the elongate member may be said to have two parallel major surfaces offset by the thickness of the FPCB, with one set of teeth contacting and gripping one major surface and the other set of teeth contacting and gripping the other major surface). 
         [0037]    The teeth of at least one clip may extend in a direction that corresponds to the length direction of the respective flexible printed circuit board harness when gripped. This may provide particularly strong resistance to the FPCB harness being pulled out of the jaw in the width direction. 
         [0038]    The teeth of at least one clip may extend in a direction that corresponds to the width direction of the respective flexible printed circuit board harness when gripped. This arrangement may facilitate insertion of the FPCB harness into the clip, and/or may provide particularly strong resistance to the FPCB harness being pulled through the jaw in the length direction. 
         [0039]    A lengthwise extending portion of the flexible printed circuit board harness may be held by two opposing clips, each opposing clip extending across no more than half of the width of the flexible printed circuit board harness. Such an arrangement may provide more secure retention of the FPCB harness. For example, such an arrangement may reduce (or substantially eliminate) the possibility of the FPCB harness being pulled out of a clip in a width direction. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0040]    The invention will now be described, by way of example only, with reference to the accompanying Figures, in which: 
           [0041]      FIG. 1  shows a gas turbine engine with a conventional harness; 
           [0042]      FIG. 2  shows perspective view of a portion of a flexible printed circuit board harness; 
           [0043]      FIG. 3  shows a side view of the flexible printed circuit board harness of  FIG. 2 ; 
           [0044]      FIG. 4  shows a top view of the flexible printed circuit board harness of  FIG. 2 ; 
           [0045]      FIG. 5  shows a cross-sectional view of the flexible printed circuit board harness of  FIG. 2 ; 
           [0046]      FIG. 6  is a cross-section through a gas turbine engine; 
           [0047]      FIG. 7  shows a side view of a clip for holding a conventional harness in place; 
           [0048]      FIG. 8  shows a perspective view of an alternative clip for holding a conventional harness in place; 
           [0049]      FIG. 9  shows a side view of the lip shown in  FIG. 8 ; 
           [0050]      FIG. 10  shows a perspective view of clip in accordance with the present invention; 
           [0051]      FIG. 11  shows a side view of two clips according to  FIG. 10 ; 
           [0052]      FIG. 12  shows a front view of an alternative clip in accordance with the present invention; and 
           [0053]      FIG. 13  shows a side view of two clips according to  FIG. 12 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0054]    With reference to  FIG. 6 , 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 . 
         [0055]    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. 
         [0056]    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. 
         [0057]    The gas turbine engine  10  shown in  FIG. 6  may be at least a part of a gas turbine engine installation according to the present invention. The gas turbine engine  10  may comprise FPCB harnesses (such as those described above in relation to  FIGS. 2 to 5 ) for transmitting/transferring electrical 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 the FPCB harnesses may be as described above and elsewhere herein. 
         [0058]    The FPCB harnesses may be attached to any part of the engine installation (of which the engine  10  may be a part) using a clip such as the clip  200  shown in  FIGS. 10 and 11 . In each of  FIGS. 10 and 11 , two clips  200 A,  200 B are shown. The two clips  200 A,  200 B may be used in conjunction with each other to hold opposing sides of a FPCB harness  20 . Alternatively, just one of the clips  200  may be used to hold a FPCB harness. 
         [0059]    Each clip  200  has three jaws  202 ,  204 ,  206  extending from (or being a part of) a main body  201 . Each jaw  202 ,  204 ,  206  may be arranged to hold (or support) a respective FPCB harness  20 . In particular, each jaw  202 ,  204 ,  206  may be arranged to receive a portion of a respective FPCB harness  20 . The number of jaws corresponds to the number of FPCB harnesses that the clip  200  can hold. In the example shown in  FIG. 11 , the clip  200  is capable of holding 3 FPCB harnesses, but is only shown holding 2 FPCB harnesses  20 . Other embodiments may thus comprise different numbers of jaws. For example, the clip  200  may have two jaws, or 4, 5, 6, 7, 8, 9, 10 or more than 10 jaws. It may also be possible to have clips with jaws of the type described and illustrated herein, but with only one jaw, although such clips with only one jaw would not have many of the advantages described herein in relation to the multi jawed clips. 
         [0060]    Each jaw  202 ,  204 ,  206  has two sets of teeth, which may be referred to as an upper set of teeth  212  and a lower set of teeth  222 . The teeth in the upper set  212  directly oppose corresponding teeth in the lower set  222 . Thus, the tips of the teeth in both sets  212 ,  222  are aligned. In the  FIG. 11  example, the teeth in both sets  212 ,  222  are aligned in the width direction of the FPCB harness that they are designed to hold, i.e. in the direction labelled ‘p’ in  FIG. 11 . Note that the direction ‘p’ labelled in  FIG. 11  corresponds to the width direction ‘y’ of the FPCB harness shown in  FIGS. 2 to 5  when inserted. 
         [0061]    A gap  232  is provided between opposing teeth, i.e. between the upper set of teeth  212  and the lower set of teeth  222 . This gap may be set according to the type of FPCB harness that the jaws  202 ,  204 ,  206  is designed to hold, for example the thickness of the FPCB harness. For example, the gap  232  may be set to be no greater than the thickness (the ‘z’ direction shown in  FIGS. 2 to 5 ) of the FPCB harness being held. The gap  232  could be different for the jaws  202 ,  204 ,  206  of the same clip  200 , if, for example, the clip  200  is intended to carry/hold FPCB harnesses of different thicknesses. In the example shown in  FIG. 11 , however, the gap  232  is the same for all jaws  202 ,  204 ,  206 . 
         [0062]    Some embodiments may have no gap  232  between opposing teeth  212 ,  222 . Such embodiments may be particularly suitable, for example, to holding especially thin FPCB harnesses. The opposing sets of teeth  212 ,  222  do not, however, overlap in the direction labelled ‘q’ in  FIG. 11  (which corresponds to the thickness direction of the FPCB harness shown in  FIGS. 2 to 5  when installed). Thus the teeth  212 ,  222  are not intermeshed. Indeed, because the upper and lower sets of teeth  212 ,  222  are directly opposed to each other, they do not intermesh even if they are pushed together. Instead, the tips of two opposing teeth  211 ,  213  may contact each other if pushed together in the ‘q’ direction, but may not pass each other. 
         [0063]    Because the upper and lower sets of teeth directly oppose each other, and thus cannot overlap so as to become intermeshed, more than one FPCB harness can be inserted into the clip  200  (and subsequently gripped by the teeth  212 ,  222  so as to be held) without undue difficulty. For example, even when one of the FPCB harnesses  20  has been inserted into one of the jaws (for example jaw  206 ), the opposing teeth of the other jaw(s)  202 ,  204  are prevented from becoming intermeshed, and thus further FPCB harnesses can be inserted into those jaws  202 ,  204  without undue hindrance. 
         [0064]    In order to insert an FPCB harness  20  into a jaw  202 ,  204 ,  206 , any suitable technique could be used. For example, the FPCB harness  20  could be pushed into the respective jaw  202 ,  204 ,  206  in the width direction of the FPCB harness  20 , i.e. in the direction labelled ‘p’ in  FIG. 11 , through the mouth  240  of the jaw  206 . Where only one clip  200  is used to hold a given FPCB harness  20 , no further steps may be required in order for it to be gripped by the sets of teeth  212 ,  222 . Where two clips  200 A,  200 B are used to hold a FPCB harness  20 , the first clip  200 A may be secured to the desired component, the FPCB harness may be inserted into the first clip  200 A as described above, then the second clip  200 B may be slid over the other side (in a width sense) of the FPCB harness, then the second clip  200 B may be secured to the component. Of course, these are only examples of many possible ways in which an FPCB harness  20  could be attached to a component using one clip  200  or two clips  200 A,  200 B, and any suitable method may be used. 
         [0065]    Once inserted, the FPCB harness is held by the clip  200 , for example through being gripped by the opposing teeth  212 ,  222 , which may be compliant and/or flexible and/or elastically deformable. The teeth  211 ,  213  of the  FIGS. 10 and 11  embodiment have blunt tips  215 . The tips  215  are squared off, and thus do not terminate in a sharp point or line. The teeth  211 ,  213  may thus be said to be truncated wedges. The teeth may be said to be elongate, with a longitudinal axis extending in the length direction of the FPCB harness that they are designed to receive. 
         [0066]      FIGS. 12 and 13  show a further embodiment of clip  300  for use in the present invention. The clip  300  also has three jaws  302 ,  304 ,  306 . Each of the jaws  302 ,  304 ,  306  may receive a FPCB harness, although no such harnesses are shown in  FIGS. 12 and 13 . The clip  300  of  FIGS. 12 and 13  shares many aspects and/or features with the embodiment of  FIGS. 10 and 11 . For example, each jaw  302 ,  304 ,  306  has opposing, non-overlapping sets of teeth  312 ,  322  which share advantages with the sets of teeth  212 ,  222  described above in relation to  FIGS. 10 and 11 . 
         [0067]    In the  FIGS. 12 and 13  clip  300 , however, the teeth  311 ,  313  are arranged at right angles to the direction of the teeth  211 ,  213  in the  FIGS. 10 and 11  embodiment. The teeth  311 ,  313  in the  FIGS. 12 and 13  embodiment are elongate teeth with a longitudinal axis running in the width direction ‘y’ of the FPCB harness  20  that they are designed to receive. Thus, in the  FIGS. 12 and 13  clip  300 , the upper and lower sets of teeth  312 ,  322  are aligned in the direction labelled ‘r’ in  FIG. 12 , so as to be directly opposed. 
         [0068]    The clips  200 ,  300  shown in  FIGS. 10 to 13  have a support structure  400 . The support structure provides support to the main body  201 ,  301  of the clip so as to restrict or minimize flexing/bending of the clip  200 ,  300 . The support structure  400  may thus be stiffer, for example constructed from a stiffer material, than the main body of the clip  201 ,  301 . The support structure  400  shown in the Figures is attached (for example bonded) to external surfaces of the main body  201 ,  301 . However, other arrangements of support structure  400  may be used. For example, the support structure may penetrate into the material of the main body  201 ,  301  of the clips  200 ,  300 , for example between the jaws. The support structure  400  shown in the Figures comprises two parts  410 ,  420 , that may be attached together (for example by welding) to produce the final support structure  400 . Again, other constructions could be used in clips for alternative embodiments. 
         [0069]    The support structure  400  shown in the figures has an attachment portion  430  which in the illustrated example comprises a hole for receiving a fixing element, such as a screw, bolt, or rivet) that is configured to allow the clip  200 ,  300  to be attached to a component, for example of the gas turbine installation. As mentioned above, this may be a particularly convenient, lightweight and compact arrangement for connecting the clips  200 ,  300 , and thus the FPCB harnesses  20 , to components. However, some clips for use in embodiments of the invention may not have a support structure  400  at all, or may have a support structure  400  without an attachment portion  430 . 
         [0070]    Any suitable material may be used to manufacture the main body  201 ,  301  of the clips  200 ,  300 , which may be the same as the material used to manufacture the jaws  202 ,  204 ,  206 ,  302 ,  304 ,  306 . For example, the material may comprise one or more of ethylene-propylene rubber, a silicone based compound, and a nitrile material. In clips which have a support structure  400 , the support structure  400  may be constructed from a stiffer material than the main body  201 ,  301 , for example from a metal and/or a resin/fibre composite. 
         [0071]    The clip  200 ,  300  could be any suitable size required to hold a FPCB harness  20 . Purely by way of non-limitative example, and with reference to  FIG. 10 , the width ‘w’ of the clip  200 ,  300  may be in the range of from 5 mm to 200 mm, for example 10 mm to 150 mm, for example 25 mm to 100 mm, for example on the order of 50 mm. The length ‘l’ of the clip  200 ,  300  may be in the range of from 5 mm to 500 mm, for example 10 mm to 200 mm, for example 25 mm to 100 mm, for example on the order of 50 mm. The height ‘h’ of the clip  200 ,  300  may be in the range of from 0.5 mm to 50 mm for example 2 mm to 10 mm, for example 3 mm to 8 mm, for example on the order of 5 mm. In other embodiments, the dimensions ‘l’, ‘h’, and ‘w’ may be outside these ranges. 
         [0072]    Where reference is made herein to a gas turbine engine installation, it will be appreciated that this term may include a gas turbine engine and/or 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 installation’ 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, industrial 
         [0073]    It will be appreciated that many alternative configurations and/or arrangements of the clips  200 ,  300  other than those described herein may fall within the scope of the invention. For example, alternative arrangements of jaws  202 , teeth sets  212 ,  222 , tooth geometry  211  (such as tip geometry  215 ), support structure  400 , and/or FPCB harness  20  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.