Abstract:
A gas turbine engine installation is provided that has a flexible printed circuit board (FPCB) harness to transfer electrical signals, including electrical power, around a gas turbine engine. The FPCB harness is held to the gas turbine engine installation using clips. The clips have a jaw that has two sets of opposing teeth extending from a base, and a mouth through which the FPCB harness is inserted. The teeth point in a direction that has a component from the mouth to the teeth. This means that the force required to insert the FPCB harness into the clip is lower than the force required to pull the FPCB harness out of the clip in the opposite direction. This means that the FPCB harness can be secured in place whilst aiding ease of assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based upon and claims the benefit of priority from British Patent Application Number 1119038.6 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 is 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. 
         [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  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. 
         [0010]    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. 
         [0011]    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. 
         [0012]    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. 
         [0013]    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 . 
         [0014]    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. 
         [0015]    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. 
         [0016]    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. 
         [0017]    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  58  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. 
         [0018]      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 
       [0019]    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. 
         [0020]    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. 
         [0021]    According to an aspect of the invention, there is provided a gas turbine engine installation comprising: a flexible printed circuit board harness arranged to transfer electrical signals around the engine installation; and at least one clip holding the printed circuit board harness. Each clip comprises a jaw extending from a base. The jaw comprises: a mouth having a width w for receiving the flexible printed circuit board harness; an upper set of teeth; and a lower set of teeth. Each tooth is compliant and has a root and a tip, and extends across at least a part of the width of the mouth. The teeth of at least one of the upper set and the lower set extend from root to tip in a direction that has a component pointing from the mouth to the base. 
         [0022]    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 . 
         [0023]    The teeth may be substantially wedge shaped, extending from a base to a relatively narrow tip. The wedge shape may have a substantially pointed cross section (which may, for example, be substantially triangular, optionally with straight or curved sides) which extends (or is extruded) along the width of the mouth. The teeth of the upper and/or lower set may be said to point (or have a component that points) in the direction of FPCB harness insertion into the jaw through its mouth. 
         [0024]    Arranging the clip in the manner set out above, may enable the FPCB harness to be inserted into the mouth of the clip more easily than it can be pulled out of the clip. This allows, for example, the FPCB harness to be secured in place whilst facilitating assembly. 
         [0025]    According to the invention, there is provided a method of assembling a gas turbine engine installation comprising: providing a flexible printed circuit board harness arranged to transfer electrical signals around the engine installation; and attaching the flexible printed circuit board harness to the rest of the gas turbine engine installation by inserting a portion thereof into a mouth of a jaw of a clip, the jaw extending from a base of the clip, and the mouth extending across a width w. The jaw comprises an upper set of teeth and a lower set of teeth. Each tooth is compliant and has a root and a tip, and extends across at least a part of the width of the mouth. The teeth of at least one of the upper set and the lower set extend from root to tip in a direction that has a component pointing from the mouth to the base of the jaw such that the force required to insert the flexible printed circuit board harness into the mouth of the jaw is lower than the force required to remove the flexible printed circuit board harness from the mouth of the jaw. 
         [0026]    This method provides various advantages, including those outlined above and elsewhere herein in relation to the gas turbine engine installation. 
         [0027]    The teeth of the upper set and the lower set may be offset such that the tips of the upper set are not directly opposed to tips of the lower set. This may further assist in reducing the force required to insert the FPCB harness by ensuring that only one tooth at a time need to be deformed in order to insert the FPCB harness into the jaw. This arrangement may also assist in spreading the load exerted by the teeth across the FPCB harness once it has been inserted. 
         [0028]    The tips of the upper set of teeth may overlap with the tips of the lower set of teeth, such that the upper and lower set of teeth may be intermeshed, at least prior to the FPCB harness being inserted. This may be a particularly suitable arrangement for holding FPCB harnesses that are particularly thin because the compliant teeth would provide sufficient gripping force once displaced/deformed by the FPCB harness. However, in other arrangements the tips of the upper and lower set of teeth may not overlap, and thus the teeth may not intermesh, even when in an undeformed state, such as prior to insertion of the FPCB harness. 
         [0029]    The teeth of both the upper set and the lower set may extend from root to tip in a direction that has a component pointing from the mouth to the base. This may increase the difference between the force required to insert the FPCB harness into the clip and the force required to remove the FPCB harness from the clip. 
         [0030]    The teeth may extend across substantially the full width of the mouth of the jaw. The mouth may extend across substantially the full width of the jaw. This may provide maximum gripping area per tooth for a given size of clip. 
         [0031]    The jaw may be formed using a material comprising one or more of: ethylene-propylene rubber, a silicone based compound, and a nitrite 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]    The clip may 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 jaw. 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 harness is clamped with the desired force. 
         [0033]    The clip may comprise a main body that may incorporate the jaw and the base. The main body may thus be integral with the jaw and the base, for example, manufactured from the same material and/or in the same process as the jaw and the base. 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 jaw 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 width of the mouth, across which the teeth extend, may be arranged to be substantially aligned with the length direction of flexible printed circuit board harness. This may allow effective gripping of the inserted FPCB harness to ensure that it does not move, or fall out, through the mouth of the jaw. 
         [0038]    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 of the FPCB harness. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0039]    The invention will now be described, by way of example only, with reference to the accompanying Figures, in which: 
           [0040]      FIG. 1  shows a gas turbine engine with a conventional harness; 
           [0041]      FIG. 2  shows perspective view of a portion of a flexible printed circuit board harness; 
           [0042]      FIG. 3  shows a side view of the flexible printed circuit board harness of  FIG. 2 ; 
           [0043]      FIG. 4  shows a top view of the flexible printed circuit board harness of  FIG. 2 ; 
           [0044]      FIG. 5  shows a cross-sectional view of the flexible printed circuit board harness of  FIG. 2 ; 
           [0045]      FIG. 6  is a cross-section through a gas turbine engine; 
           [0046]      FIG. 7  shows a side view of a clip for holding a conventional harness in place; 
           [0047]      FIG. 8  shows a perspective view of an alternative clip for holding a conventional harness in place; 
           [0048]      FIG. 9  shows a side view of the clip shown in  FIG. 8 ; 
           [0049]      FIG. 10  shows a side view of clip in accordance with the present invention; 
           [0050]      FIG. 11  shows a perspective view of the clip according to  FIG. 10 ; 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0051]    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 . 
         [0052]    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. 
         [0053]    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. 
         [0054]    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. 
         [0055]    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 , just one clip  200  is shown. The FPCB harness could be held at a lengthwise position by just one clip  200 . Alternatively, two clips  200  may be used in conjunction with each other to hold opposing sides of a FPCB harness  20  at a given lengthwise position. 
         [0056]    The clip  200  has a base, or base portion,  210 . A jaw  220  extends from the base  210 . Together, the jaw  220  and the base  210  may be said to form a main body of the clip  200 . The jaw  220  comprises an upper set of teeth  230  and a lower set of teeth  240 . The upper set of teeth  230  and the lower set of teeth  240  form a jaw opening, or mouth,  250 . The mouth  250  is configured to receive a FPCB harness  20 . As shown in  FIG. 10 , the FPCB harness may be inserted into the mouth  250  in a direction ‘p’. The direction ‘p’ may be substantially aligned with the width direction ‘y’ of the FPCB harness  20 . 
         [0057]    In the clip shown in  FIGS. 10 and 11 , the teeth are angled towards the base  210 . Thus, the direction ‘u’ in which the upper teeth point and the direction ‘l’ in which the lower teeth point (which may be referred to as the direction in which the upper and lower teeth extend from root  231 ,  241  to tip  233 ,  243 ) both have a component in the direction from the mouth  250  to the base  210 . As shown in  FIG. 10 , the direction from the mouth  250  to the base  210  may correspond to the direction ‘p’ of insertion of the FPCB harness  220  into the clip  200 . 
         [0058]    In some embodiments, not all of the teeth, i.e. just some of the teeth  232 ,  242 , may extend (or point) in a direction that has a component in the direction from the mouth  250  to the base  210 . For example, in some embodiments, only the teeth  232  of the upper set of teeth  230  may extend (or point) in a direction that has a component in the direction from the mouth  250  to the base  210 . In other embodiments only the teeth  242  of the lower set of teeth  240  may extend (or point) in a direction that has a component in the direction from the mouth  250  to the base  210 . A gas turbine engine comprising one or more FPCB harnesses  20  may comprise any combination of the various clips in accordance with the invention, optionally in addition to other clips that may not be in accordance with the invention. 
         [0059]    When the FPCB harness  20  is inserted into the jaw  220  of the clip  200 , the upper teeth  232  deflect upwards (towards their root  231 ) and in the direction of insertion and the lower teeth  242  deflect downwards (towards their root  241 ) and in the direction of insertion. In  FIG. 10 , the arrow ‘a’ represents this deflection for the upper set of teeth, and the arrow ‘b’ represents this deflection for the lower set of teeth. It is easier to move the FPCB in the insertion direction ‘p’ than in the removal direction (which is the opposite direction to the insertion direction ‘p’). This may be because deflection of the teeth that extend in a direction that has a component in the direction from the mouth  250  to the base  210  when pushed in the insertion direction ‘p’ causes them to move away from the major surface of the FPCB  20 , towards their root (as illustrated by arrows ‘a’ and ‘b’) whereas deflection of those teeth when pushed in the removal direction causes them to move towards the major surface of the FPCB  20 , away from their root, thus causing those teeth to grip the FPCB harness  20  more tightly. Additionally or alternatively, the force required to deflect the teeth that extend in a direction that has a component in the direction from the mouth  250  to the base  210  may be lower in the insertion direction than in the removal direction. 
         [0060]    Thus, once inserted, the FPCB harness  20  is held by the clip  200 , for example through being gripped by the opposing sets of teeth  230 ,  240 , which may be compliant and/or flexible and/or elastically deformable. In order to remove the FPCB harness  20  through the mouth  250  of the clip  200 , a greater force is required than that which was required to insert it. 
         [0061]    The teeth  232 ,  242  of  FIGS. 10 and 11  are shown as having substantially triangular cross-sections extending in the direction of the width ‘w’ of the mouth  250  of the clip  200  to form substantially wedge shaped teeth (note that this width ‘w’ of the mouth  250  may extend in substantially the same direction as the local length direction ‘x’ of the FPCB harness  20  being held by the clip  200 ). In other embodiments, the cross sections could be other shapes, for example two curved surfaces extending from a root to a tip. The teeth  232 ,  242  may or may not extend across the full width ‘w’ of the mouth  250 . For example, there could be one or more gap(s) in the teeth in the width direction, such that two (or more) teeth extend next to each other in the width direction ‘w’. 
         [0062]    The teeth  232  of the upper set  230  and the teeth  242  of the lower set  240  are offset in the insertion direction ‘p’, such that their tips  233 ,  243  are not directly opposed. In other embodiments, the upper teeth  232  and the lower teeth  242  may be directly opposed, although this would require them not to overlap (in the direction labelled ‘q’ in  FIG. 10 ). In the clip  200  shown in  FIGS. 10 and 11 , the upper teeth  232  and the lower teeth  242  do overlap, and thus intermesh in the undeformed state (i.e. when the FPCB harness is not inserted into the clip  200 ). The extent of overlap of the tips  233 ,  243  of the teeth  232 ,  242 , or the gap between the tips  233 ,  243  in the overlap direction ‘q’, may depend on the thickness (in the ‘z’ direction) of the FPCB harness  20 . Thus, thicker FPCB harnesses  20  may require less overlap, no overlap, or separation between the tips  233 ,  243  of the upper and lower teeth, 
         [0063]    The clip  200  shown in  FIGS. 10 and 11  has a support structure  400 . The support structure  400  provides support to the main body  201  of the clip so as to restrict or minimize flexing/bending of the clip  200 . The support structure  400  may thus be stiffer, for example constructed from a stiffer material, than the main body of the clip. The support structure  400  shown in the Figures is attached (for example bonded) to external surfaces of the main body. However, other arrangements of support structure  400  may be used. For example, the support structure may penetrate into the material of the main body of the clip  200 . 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. 
         [0064]    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  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 clip  200 , 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 . 
         [0065]    Any suitable material may be used to manufacture the main body of the clip  200 . 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, for example from a metal and/or a resin/fibre composite. 
         [0066]    The dip  200  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. 
         [0067]    Whilst the clip  200  has been described with reference to  FIGS. 10 and 11  that have just one jaw  220 , other embodiments may comprise more than one jaw, and thus may be able to accept and hold more than one FPCB harness  20 . 
         [0068]    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 
         [0069]    It will be appreciated that many alternative configurations and/or arrangements of the clip  200  other than those described herein may fall within the scope of the invention. For example, alternative arrangements of jaw  220 , teeth sets  230 ,  240 , tooth geometry  232 ,  242  (such as tip geometry  233 ,  243 ), 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.