Patent Publication Number: US-2022234316-A1

Title: Quick-repair patch for renovating external damage, and quick-repair method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to German Patent Application No. 10 2021 101 981.8 filed Jan. 28, 2021, the entire disclosure of which is incorporated by reference herein. 
     TECHNICAL FIELD 
     The disclosure herein relates to a quick-repair patch, preferably for aircraft, and to a quick-repair method. The disclosure herein also relates to a repair arrangement and to uses of a quick-repair patch. 
     BACKGROUND 
     Civilian and military aircraft, helicopters and drones, and also motor vehicles, ships and wind turbines (or their rotor blades) are customarily produced from metal or composite materials. In the event of a lightning strike, repairs can be necessary. The most common type of damage in the event of a lightning strike is merely superficial damage, i.e. damage to the paint and possibly to a few deeper layers. This generally results in no significant material damage which can adversely affect the structure. 
     After such an incident, local and structurally mechanically irrelevant damage (scratches, lacquer chipping, tufting and the like) of this type has up to now been temporarily repaired by what is known as a high-speed tape (HST, self-adhesive aluminum foil) on account of temporal restrictions and limited repair opportunities. HST is favorable and available at many airports. 
     SUMMARY 
     An object of the disclosure herein is to improve quick repairs of local and structurally mechanically irrelevant damage, such that in particular not only operability but also functionality can be established. 
     The object is achieved by the subject matter disclosed herein. Preferred developments are disclosed herein. 
     The disclosure herein provides a quick-repair patch, which serves to renovate local and structurally mechanically irrelevant damage to a component, preferably to an aircraft component, which contains a covering layer and lightning-strike surface protection located therebeneath, wherein the quick-repair patch has a layer structure and the layer structure comprises:
         a plastic film layer, which can be materially bonded to the covering layer and faces away from the damage when the quick-repair patch fastened to the component;   an electrically conductive lightning-protection layer, which is suitable for a lightning-protection function or an electromagnetic-interference-protection function, is arranged on the plastic film layer and makes electrically conductive contact with the lightning-strike surface protection when the quick-repair patch is fastened to the component;   a fastening layer, which is suitable for fastening the quick-repair patch to the component by a material bond and which is arranged at least on the plastic film layer on the same side as the electrically conductive lightning-protection layer.       

     It is preferred that the plastic film layer contains reinforcing fibers. It is preferred that the plastic film layer contains a material that attenuates radar radiation, preferably absorbs radar radiation. It is preferred that the plastic film layer contains an electrically conductive material. It is preferred that the plastic film layer contains a material that attenuates, preferably absorbs, UV light or ionizing radiation. 
     It is preferred that the plastic film layer is electrically insulated from the lighting-protection layer. 
     It is preferred that the plastic film layer has a larger surface area than the lightning-protection layer, wherein the plastic film layer has a peripheral region which is arranged between the outer contour of the plastic film layer and the outer contour of the lightning-protection layer. 
     It is preferred that the fastening layer is applied to the peripheral region or is arranged on the peripheral region. 
     It is preferred that the layer structure has a functional layer. It is preferred that the functional layer is arranged on that side of the plastic film layer that faces away from the lightning-protection layer. It is preferred that the functional layer has a reinforcing function, a camouflage function, a static-discharge-protection function and/or a protective function against radiation, in particular against UV radiation and/or ionizing radiation. 
     It is preferred that the layer structure comprises a reinforcing layer, which contains reinforcing fibers and is arranged on the plastic film layer. It is preferred that the layer structure comprises a camouflage layer, which contains a material that attenuates radar radiation, preferably absorbs radar radiation. It is preferred that the layer structure comprises an electrostatic-discharge-protection layer, which contains an electrically conductive material. It is preferred that the layer structure has a connecting layer, which is arranged between the plastic film layer and the lightning-protection layer and materially bonds them to one another. It is preferred that the layer structure has a radiation-protection layer, which contains a material that attenuates, preferably absorbs, UV light or ionizing radiation. 
     It is preferred that the reinforcing layer, the camouflage layer, the discharge-protection layer and/or the radiation-protection layer are combined in a common functional layer. It is preferred that the reinforcing layer, the camouflage layer, the discharge-protection layer, the radiation-protection layer and/or the functional layer are arranged on that side of the plastic film layer that faces away from the lightning-protection layer. 
     It is preferred that the layer structure is formed in the following sequence: plastic film layer, lightning-protection layer, fastening layer. It is preferred that the layer structure is formed in the following sequence: plastic film layer, connecting layer, lightning-protection layer, fastening layer. 
     It is preferred that the layer structure is formed in the following sequence: reinforcing layer or camouflage layer or discharge-protection layer or radiation-protection layer, plastic film layer, lightning-protection layer, fastening layer. It is preferred that the layer structure is formed in the following sequence: reinforcing layer or camouflage layer or discharge-protection layer or radiation-protection layer, plastic film layer, connecting layer, lightning-protection layer, fastening layer. 
     It is preferred that the layer structure is formed in the following sequence: functional layer, plastic film layer, lightning-protection layer, fastening layer. It is preferred that the layer structure is formed in the following sequence: functional layer, plastic film layer, connecting layer, lightning-protection layer, fastening layer. 
     It is preferred that the layer structure consists only of the layers mentioned. 
     The quick-repair patch preferably comprises an information tag or device, preferably a QR code and/or an RFID tag, by virtue of which specifications relating to quick repair carried out by the quick-repair patch can be stored or retrieved. It is preferred that the specifications are stored in or can be retrieved from the RFID tag. It is preferred that the specifications can be stored or retrieved by a computer using the QR code. 
     It is preferred that the information tag or device is contained in or attached to the plastic film layer. 
     The disclosure herein provides a quick-repair patch, which serves to renovate local and structurally mechanically irrelevant damage to a component, preferably to an aircraft component, which contains a covering layer and lightning-strike surface protection located therebeneath, wherein the quick-repair patch has a layer structure and the layer structure consists of:
         a plastic film layer, which can be materially bonded to the covering layer and faces away from the damage when the quick-repair patch is fastened to the component;   an electrically conductive lightning-protection layer, which is suitable for a lightning-protection function or an electromagnetic-interference-protection function, is arranged on the plastic film layer and makes electrically conductive contact with the lightning-strike surface protection when the quick-repair patch is fastened to the component;   a fastening layer, which is suitable for fastening the quick-repair patch to the component by a material bond and which is arranged at least on the plastic film layer on the same side as the electrically conductive lightning-protection layer;   optionally a connecting layer, which is arranged between the plastic film layer and the lightning-protection layer and materially bonds them to one another;   optionally a functional layer, which is arranged on that side of the plastic film layer that faces away from the lightning-protection layer.       

     It is preferred that the functional layer consists of a reinforcing layer, which contains reinforcing fibers; and/or a camouflage layer, which contains a material that attenuates radar radiation, preferably absorbs radar radiation; and/or an electrostatic-discharge-protection layer, which contains an electrically conductive material. 
     It is preferred that the plastic film layer contains reinforcing fibers. It is preferred that the plastic film layer contains a material that attenuates radar radiation, preferably absorbs radar radiation. It is preferred that the plastic film layer contains an electrically conductive material. 
     It is preferred that the plastic film layer is electrically insulated from the lighting-protection layer. 
     The disclosure herein provides a repair arrangement, which comprises a component, preferably an aircraft component, and a quick-repair patch described above, wherein the component has a covering layer and lightning-strike surface protection located therebeneath and also local and structurally mechanically irrelevant damage, wherein the quick-repair patch covers the damage and is materially bonded to the component by the fastening layer, wherein the plastic film layer is materially bonded to the covering layer and faces away from the damage, wherein the electrically conductive lightning-protection layer is arranged between the plastic film layer and the lightning-strike surface protection. 
     It is preferred that the lightning-protection layer is electrically conductively connected to the lightning-strike surface protection. 
     The disclosure herein provides an aircraft comprising a quick-repair patch described above and/or a repair arrangement described above, wherein the component is preferably selected from among lift aids, flaps, leading-edge slats, control surfaces, elevators, rudders, ailerons, fuselage parts, rotor blades, wing surfaces, engine nacelles, horizontal tail units and/or vertical tail units. 
     The disclosure herein provides a quick-repair method for renovating local and structurally mechanically irrelevant damage to a component, preferably to an aircraft component, which contains a covering layer and lightning-strike surface protection located therebeneath, wherein the method comprises: 
     1 producing a connecting surface on the component for a quick-repair patch and optionally exposing the lightning-strike surface protection; 
     2 positioning a quick-repair patch described above on the damage; and 
     3 fastening the quick-repair patch to the connecting surfaces produced in step 1 by pressing it on, as a result of which the plastic film layer is materially bonded to the covering layer. 
     It is preferred that, in step 1, the production of the connecting surfaces and/or the exposure of the lightning-strike surface protection is done e.g. by grinding. 
     It is preferred that, in step 1, the production includes cleaning, drying and/or removing grease from a surface region of the component, in order to provide the connecting surface. 
     It is preferred that, in step 2, the quick-repair patch is positioned in such a way that the lightning-protection layer can make contact with the lightning-strike surface protection. 
     It is preferred that, in step 3, the lightning-protection layer is brought into electrically conductive contact with the lightning-strike surface protection. 
     The disclosure herein provides the use of a quick-repair patch described above for repairing local and structurally mechanically irrelevant damage to an aircraft component. 
     The concept described herein makes it possible to increase the typical service life of approximately 2 months of quick repairs. Consequently, the time until complete repair in compliance with the repair manual can be lengthened. Corresponding adaptation of the plastic film makes it possible to adapt the patch to the location to be repaired, with the result that the quick repair is less visible overall. 
     Military aircraft usually have a coating that reduces the radar signature. By the quick-repair patch, what are known as hotspots, which adversely affect the radar signature, can be avoided. 
     The smart quick-repair patch (or smart quick surface repair patch, SQSR patch) presented here is a multilayered patch of predefined size and generally has three to four layers. 
     Layer 1 is a plastic film layer. This may be dyed. The plastic film layer is a polyurethane film, for example. The plastic film may contain a marking in the form of information tag or device, for example in the form of a QR code or an RFID tag. Various specifications relating to the patch and to the quick repair may be stored therein (for example the type, production date, installation date and individual number). The plastic film layer may optionally contain a reinforcement of reinforcing fibers (for example glass fibers, Kevlar). These are especially suitable for repairing fuel tanks or combat damage. The plastic film may optionally also be provided with camouflage-improving properties (for example by virtue of suitable materials that absorb or attenuate radar radiation). A colorless covering layer may also be applied. 
     Layer 2 contains electrically conductive material. The electrically conductive material used may be for example metal stretch foil, perforated metal foil, expanded metal grids, graphene or the like. This layer serves as lightning-strike surface protection (LSSP), or shielding against electromagnetic interference (EMI shielding). Depending on the material, an additional adhesive layer in the form of a connecting layer may be provided between layer 1 and layer 2. 
     Layer 3 is a fastening layer, for example made of adhesive film. This can be applied only to layer 1. This layer may additionally also be arranged on layer 2, a conductive adhesive preferably being used for this. 
     It is also possible for a layer referred to as layer 1 +  to be arranged on layer 1. This layer may optionally be configured as a reinforcing layer with the reinforcing fibers, as a camouflage layer with the camouflage-improving materials, or as electrostatic-discharge protection. The layer can also be referred to as functional layer. 
     The sequence of the layers can be adapted to the corresponding application. Similarly, the shaping of the patch can be adapted to different situations. The patch may thus be square, rectangular, circular or elliptical. The same applies for the shape of layer 2. The shape of the layer 2 may differ from the overall shape. 
     Advantageously, the quick-repair patch may be attached by a method similar to the HST method. The configuration of the patch makes it possible to better avoid peeling off. By contrast to HST, the patch is also watertight and thus increases the corrosion resistance. Even damaged logos or markings on the aircraft can be repaired with low outlay. 
     By contrast to HST, the patch makes it possible to postpone the maintenance of relatively small damage until the regular D-check. For individual cases, the patch may even be permissible as permanent repair. 
     Correspondingly, the concepts presented here allow the operator to repair surface damage more simply, more durably and more securely. The repair patch makes long-lasting protection which reduces, minimizes or even avoids surface damage associated with a lightning strike possible. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Example embodiments will be explained in more detail with reference to the appended schematic drawings, in which: 
         FIG. 1  shows an example embodiment of an aircraft; 
         FIG. 2  shows an example embodiment of a quick-repair patch; 
         FIG. 3  shows a top view of a quick-repair patch; 
         FIG. 4  shows an example embodiment of a repair arrangement having a quick-repair patch from  FIG. 2 ; and 
         FIG. 5  shows an example embodiment of a patch strip. 
     
    
    
     DETAILED DESCRIPTION 
     Reference is first of all made to  FIG. 1 , which shows an aircraft  10 . In a manner known per se, the aircraft  10  comprises a fuselage  12  on which a pair of wings  14  are arranged. A vertical tail unit  16  and a horizontal tail unit  18  are arranged on the rear end of the fuselage  12 . Each wing  14  comprises wing surfaces  20  and lift aids  22 . The wing  14 , the vertical tail unit  16  and the horizontal tail unit  18  additionally have control surfaces  24 . 
     The abovementioned components  26  ( FIG. 4  for example) may have local and structurally mechanically irrelevant damage  28  caused by a lightning strike, for example. The component  26  comprises a main body  30 . The main body  30  may be formed from metal or a fiber-reinforced plastic. The component  26  also comprises lightning-strike surface protection  32 . The lightning-strike surface protection  32  may also be formed by the main body  30  itself. In addition, the component  26  comprises a covering layer  34 , which is arranged on the lightning-strike surface protection  32 . 
       FIG. 2  through  FIG. 4  schematically show a quick-repair patch  36 , which can be used to repair the damage  28  in a repair arrangement  37  ( FIG. 4 ). The quick-repair patch has a thickness of approximately 0.1 mm to 0.2 mm. 
     The quick-repair patch  36  comprises a layer structure  38 . The layer structure  38  has a plastic film layer  40 . The plastic film layer  40  is preferably formed from a polyurethane film. The plastic film layer  40  may be dyed. The plastic film layer  40  is rectangular in the present case. The plastic film layer  40  may, however, also have other shapes, for example a circular shape, elliptical shape or square shape. 
     The layer structure  38  comprises an electrically conductive lightning-protection layer  42  arranged on one face of the plastic film layer  40 . The lightning-protection layer  42  contains an electrically conductive material of metal or graphene. The lightning-protection layer  42  may accordingly contain expanded metal, perforated metal foil and the like. The lightning-protection layer  42  has an elliptical shape in the present case. The lightning-protection layer  42  may, however, also have other shapes, for example a circular shape, rectangular shape or square shape. The lightning-protection layer  42  has a smaller surface area than the plastic film layer  40 . When viewed from the top ( FIG. 3 ), the plastic film layer  40  has a peripheral region  44 , which is arranged between the contour of the plastic film layer  40  and of the lightning-protection layer  42 . 
     Arranged between the plastic film layer  40  and the lightning-protection layer  42  in the thickness direction is a thin connecting layer  46 , which materially bonds the two layers to one another. 
     The layer structure  38  also comprises a fastening layer  48  arranged on the plastic film layer  40 . The fastening layer  48  contains an adhesive, in order to materially bond the quick-repair patch  36  to the component  26 . In a variant, the fastening layer  48  may be materially bonded to the component  26  by welding. The fastening layer  48  is preferably applied to or arranged on only the peripheral region  44 . The fastening layer  48  may additionally also be applied to the lightning-protection layer  42 . The adhesive is preferably conductive in the region of the lightning-protection layer  42 . As an alternative, a region of the lightning-protection layer  42  is exposed, in order to allow electrical contact between the lightning-protection layer  42  and the lightning-strike surface protection  32 . 
     The layer structure  38  may additionally have a functional layer  50 . The functional layer  50  is arranged on that face of the plastic film layer  40  that faces away from the lightning-protection layer  42 . 
     The functional layer  50  may have a reinforcing layer  52 , which contains reinforcing fibers. Glass fibers or Kevlar are/is used as reinforcing fibers. 
     The functional layer  50  may have a camouflage layer  54 , which contains a radar-absorbing or radar-attenuating additive or additives. 
     The functional layer  50  may contain an electrostatic-discharge-protection layer  56 , which contains conductive material. 
     The functional layer  50  is preferably in the form of an individual layer in which the reinforcing layer  52 , the camouflage layer  54  and the discharge-protection layer  56  are integrated. 
     As an alternative, the functions of the reinforcing layer  52 , the camouflage layer  54  or the discharge-protection layer  56  may be realized in the plastic film layer in any desired combination. 
     The quick-repair patch  36  may also have an information tag or device  58 , by which specifications relating to the quick-repair patch  36  and/or the quick repair carried out therewith can be stored or retrieved. Included in the specifications are the type and production date of the quick-repair patch  36 , the repair date, the repair location and any further information, in particular technical information, that is relevant for the quick-repair patch  36  or the repair as such. The information tag or device  58  may be a QR code or an RFID tag, for example. The QR code and the RFID tag may each serve as a reference for the corresponding specifications, which are stored in a computer system or computer network. The RFID tag may also be designed such that it contains the specifications directly. 
     A quick repair will be explained in more detail below with reference to  FIG. 4 . The damage  28  is first of all machined, e.g. by grinding, to afford a smooth, clean, dry and grease-free connecting surface  60  for the quick-repair patch  36 . 
     Then, an appropriate quick-repair patch  36  is selected and placed over the damage  28  in such a way that the damage is completely covered. Subsequently, the quick-repair patch  36  is pressed onto the component  26 . In the process, the plastic film layer  40 , in particular the peripheral region  44 , is pressed against the covering layer  34  and materially bonded thereto by way of the fastening layer  48 . Furthermore, the lightning-protection layer  42  is pressed against the lightning-strike surface protection  32 , resulting in electrical contact. If it is also the case that the lightning-protection layer  42  is coated with adhesive, then the lightning-protection layer  42  is also materially bonded to the lightning-strike surface protection  32 . 
     Reference is made below to  FIG. 5 , which shows a form of administration of quick-repair patches  36  in the form of a patch strip  62 . In this context, a plurality of quick-repair patches  36  are connected to one another at a separable edge region  64 , for example by a perforation. The patch strip  62  may be wound up in a roll. The desired quick-repair patch  36  is separated from the patch strip  62  prior to use. 
     In order to improve quick repairs of local and structurally mechanically irrelevant damage ( 28 ) to aircraft components ( 26 ), a quick-repair patch ( 36 ) is proposed. The quick-repair patch ( 36 ) has a layer structure ( 38 ) with a plastic film ( 40 ), to which lightning protection ( 42 ) is applied, and an adhesive layer ( 48 ), which is arranged at least on the plastic film ( 40 ). The quick-repair patch ( 36 ) may be adhesively bonded to the damage ( 28 ) such that the lightning protection ( 42 ) is in electrical contact with the lightning protection of the component ( 26 ). The quick-repair patch ( 36 ) may have a QR code or an RFID tag, by way of which specifications relating to the quick-repair patch ( 36 ) or to the quick repair ( 36 ) can be stored or retrieved. 
     While at least one example embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the example embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a”, “an” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority. 
     LIST OF REFERENCE DESIGNATIONS 
     
         
         
           
               10  Aircraft 
               12  Fuselage 
               14  Wing 
               16  Vertical tail unit 
               18  Horizontal tail unit 
               20  Wing surface 
               22  Lift aid 
               24  Control surface 
               26  Component 
               28  Damage 
               30  Main body 
               32  Lightning-strike surface protection 
               34  Covering layer 
               36  Quick-repair patch 
               37  Repair arrangement 
               38  Layer structure 
               40  Plastic film layer 
               42  Lightning-protection layer 
               44  Peripheral region 
               46  Connecting layer 
               48  Fastening layer 
               50  Functional layer 
               54  Camouflage layer 
               56  Discharge-protection layer 
               58  Information tag or device 
               60  Connecting surface 
               62  Patch strip 
               64  Edge region