Repairing hat stringer

Abstract

To provide a method of repairing a hat stringer.SOLUTION: The method includes arranging a repair stringer in a mounting location that is one of multiple possible mounting locations along a cross section of a hat stringer. In each of the multiple mounting locations, at least a portion of an internal profile of the repair stringer matches at least a portion of a profile of an internal cavity defined by the hat stringer. The cross-sectional area of the repair stringer as viewed along a first direction is less than the total cross-sectional area of the hat stringer as viewed along the first direction. The method also includes coupling the repair stringer with a stringer of the hat stringer in the mounting location. Repair stringers and repaired hat stringers are also presented.SELECTED DRAWING: Figure 3B

Description

[Technical field]

[0001] Aspects of the present disclosure relate to the repair of structural components of aircraft, and more particularly, to the repair of hat stringers. [Background technology]

[0002]

[0002] Aircraft structures must be able to handle a wide variety of loads in different directions. For example, an aircraft wing must be able to handle the aerodynamic loads imposed on the wing during flight. Such aerodynamic loads include bending loads that the wing skin and the wing internal structure react to. Typically, in the wing internal structure, stiffeners or stringers react to the bending loads. The stringers are connected to the wing skin and extend generally spanwise along the wing internal. Stringers can be provided in a wide variety of different cross-sectional shapes and sizes, including having a hat-shaped cross-section. Hat stringers (or simply hat stringers) typically include a pair of webs that extend from a base of the stringer and are connected by a cap to form a hat-shaped cross-section.

[0003]

[0003] In some cases, hat stringers may become damaged (e.g., from a crash event) or otherwise require reinforcement. Conventional techniques for repairing damaged hat stringers present several challenges. Thus, there is a need for one or more improved hat stringer repair techniques and / or repair stringers. Summary of the Invention

[0004] In one aspect, the disclosure provides a method of repairing a hat stringer, the method including positioning a repair stringer at one of a plurality of possible attachment locations along a cross-section of the hat stringer, where at each of the plurality of possible attachment locations, at least a portion of an interior contour of the repair stringer matches at least a portion of a contour of an interior cavity defined by the hat stringer, and where a cross-sectional area of ​​the repair stringer as viewed along a first direction is less than a total cross-sectional area of ​​the hat stringer as viewed along the first direction. The method also includes coupling the repair stringer to a stringer of the hat stringer at the attachment location.

[0005]

[0005] In some further aspects that can be combined with any of the exemplary methods above or below, at each of a plurality of possible attachment points, the repair stringer has a web segment that extends parallel to a web portion of the contour of the internal cavity.

[0006]

[0006] In some further aspects combined with any of the exemplary methods above or below, at each of a plurality of possible attachment points, the repair stringer has at least one segment extending parallel to a cap portion of the internal cavity or a flange segment of the stringer.

[0007]

[0007] In some further aspects combined with any of the exemplary methods above or below, the hat-shaped stringer defines a midplane dividing a first side and a second side of the hat-shaped stringer, and the plurality of possible attachment locations includes a first possible attachment location where the repair stringer is primarily positioned on the first side of the hat-shaped stringer, and a second possible attachment location where the repair stringer is primarily positioned on the second side of the hat-shaped stringer.

[0008]

[0008] In some further aspects combined with any of the exemplary methods above or below, the repair stringer has a cap segment, a flange segment, and a web segment extending between and connecting the cap segment and the flange segment, and when the repair stringer is positioned at the installation location, the cap segment, web segment, and flange segment of the repair stringer extend parallel to the cap segment, web segment, and flange segment of the stringer, respectively.

[0009]

[0009] In some further aspects that can be combined with any of the exemplary methods above or below, the repair stringer is a first repair stringer, and the method further includes placing a second repair stringer at an attachment location along the cross-section of the hat-shaped stringer, the second repair stringer being shaped to have an inner contour that matches at least a portion of the contour of the internal cavity, and a cap segment of the second repair stringer and a cap segment of the first repair stringer physically overlap each other and each extend parallel to the cap portion of the contour of the internal cavity.

[0010]

[0010] In some further aspects that can be combined with any of the above or below exemplary methods, the first repair stringer has a web segment that physically overlaps with a first web segment of the stringer, and the second repair stringer has a web segment that physically overlaps with a second web segment of the stringer.

[0011]

[0011] In some further aspects that can be combined with any of the exemplary methods above or below, the second repair stringer has a flange segment that extends parallel to but is spaced apart from the second flange segment of the stringer, and the method further includes positioning one or more shims between the second flange segment and the flange segment of the second repair stringer.

[0012]

[0012] In some further aspects combined with any of the exemplary methods described above or below, the second repair stringer has the same cross-sectional shape as the first repair stringer when viewed along the first direction.

[0013] In yet another aspect that may be combined with any of the above or below exemplary methods, the method further includes placing a second repair stringer at an attachment location along the cross section of the hat stringer, the second repair stringer being shaped to have an inner contour that matches at least a portion of the contour of the internal cavity. The method also includes placing a third repair stringer at an attachment location along the cross section of the hat stringer, the third repair stringer having a first web segment, a cap segment, and a second web segment. The first web segment is connected to the repair stringer, the cap segment is connected to the stringer, and the second web segment is connected to the second repair stringer.

[0014]

[0014] In some further aspects in combination with any of the exemplary methods described above or below, the hat-shaped stringer defines a midplane dividing a first side and a second side of the hat-shaped stringer, and the plurality of possible attachment points includes at least four possible attachment points, the at least four possible attachment points including at least two possible attachment points where the repair stringer can be primarily positioned on the first side of the hat-shaped stringer and at least two possible attachment points where the repair stringer can be primarily positioned on the second side of the hat-shaped stringer.

[0015]

[0015] In some further aspects combined with any of the exemplary methods above or below, the at least two possible attachment points at which the repair stringer can be positioned primarily on the first side of the hat-shaped stringer include a first attachment point and a second attachment point, where at the first attachment point, one segment of the repair stringer extends parallel to a first flange segment of the stringer and another segment of the repair stringer extends parallel to a first web segment of the stringer, and where at the second attachment point, one segment of the repair stringer extends parallel to a cap segment of the stringer and another segment of the repair stringer extends parallel to the first web segment of the stringer.

[0016]

[0016] In some further aspects combined with any of the exemplary methods described above or below, the at least two possible attachment points where the repair stringer is positioned primarily on the second side of the hat-shaped stringer include a first attachment point and a second attachment point, where at the first attachment point, one segment of the repair stringer extends parallel to the cap segment of the stringer and another segment of the repair stringer extends parallel to the second web segment of the stringer, and where at the second attachment point, one segment of the repair stringer extends parallel to the second flange segment of the stringer and another segment of the repair stringer extends parallel to the second web segment of the stringer.

[0017]

[0017] In some further aspects combined with any of the exemplary methods described above or below, the stringer includes a first flange segment, a first web segment, a cap segment, a second web segment, and a second flange segment, and the multiple possible attachment points along a cross section of the hat stringer include a first attachment point, a second attachment point, a third attachment point, and a fourth attachment point, and at the first attachment point, one segment of the repair stringer extends parallel to the first flange segment of the stringer, and another segment of the repair stringer extends parallel to the first web segment of the stringer, and at the second attachment point, at a third attachment location, one segment of the repair stringer extends parallel to the cap segment of the stringer and another segment of the repair stringer extends parallel to the first web segment of the stringer; at a fourth attachment location, one segment of the repair stringer extends parallel to the cap segment of the stringer and another segment of the repair stringer extends parallel to the second web segment of the stringer; and at a fourth attachment location, one segment of the repair stringer extends parallel to the second flange segment of the stringer and another segment of the repair stringer extends parallel to the second web segment of the stringer.

[0018]

[0018] In some further aspects combined with any of the exemplary methods above or below, the repair stringer is a first repair stringer, the attachment point is a first attachment point, and the method further includes positioning a second repair stringer at the second attachment point, positioning a third repair stringer at the third attachment point, and positioning a fourth repair stringer at the fourth attachment point, and connecting the second repair stringer, the third repair stringer, and the fourth repair stringer to the stringer at the second attachment point, the third attachment point, and the fourth attachment point, respectively, wherein the first repair stringer is connected to the stringer at the first attachment point.

[0019]

[0019] In some further aspects that can be combined with any of the above or below exemplary methods, the first repair stringer and the second repair stringer physically overlap each other, the second repair stringer and the third repair stringer physically overlap each other, and the third repair stringer and the fourth repair stringer physically overlap each other.

[0020]

[0020] In some further aspects that can be combined with any of the exemplary methods described above or below, the first repair stringer, the second repair stringer, the third repair stringer, and the fourth repair stringer all have the same cross-sectional shape when viewed along a first direction, the second repair stringer is oriented vertically and horizontally flipped relative to the first repair stringer, the third repair stringer is oriented vertically flipped relative to the first repair stringer, and the fourth repair stringer is oriented horizontally flipped relative to the first repair stringer.

[0021] In some further aspects in combination with any of the exemplary methods described above or below, the repair stringer is a first repair stringer, the first repair stringer is positioned such that a segment of the first repair stringer is located in or adjacent to a plane in which the missing section of the stringer was previously located, and the method further comprises: a segment of the second repair stringer and a segment of the third repair stringer are positioned in said plane or adjacent to said plane in which the missing section of the stringer was previously located. The method includes positioning a second repair stringer and a third repair stringer so as to sandwich a segment of a first repair stringer positioned adjacent to the plane; positioning a fourth repair stringer so that the segment of the fourth repair stringer and the first repair stringer sandwich the second repair stringer; and connecting the first repair stringer, the second repair stringer, the third repair stringer, and the fourth repair stringer to each other and to the stringers.

[0022] In another aspect, a method is provided that includes positioning a first repair stringer along a cross section of a hat stringer, the first repair stringer having an inner contour that matches at least a portion of a contour of an internal cavity defined by the hat stringer, and positioning a second repair stringer along the cross section of the hat stringer, the second repair stringer having an inner contour that matches at least a portion of a contour of the internal cavity, the first repair stringer and the second repair stringer being positioned such that a segment of the second repair stringer physically overlaps a segment of the first repair stringer, the method further including connecting the first repair stringer and the second repair stringer to a stringer of the hat stringer.

[0023] In a further aspect, a repair stringer is provided that includes a web segment having an inner contour shaped to match a web portion of a contour of an internal cavity defined by the hat stringer, and at least one of a cap segment and a flange segment extending from the web segment, the repair stringer having a partial cross section relative to a total cross section of the hat stringer.

[0024]

[0024] In another aspect, a method is provided that includes positioning a first repair stringer such that a segment of the first repair stringer is located in or adjacent to a plane in which the missing section of the base stringer was previously located. The method further includes positioning a second repair stringer and a third repair stringer such that the second repair stringer segment and the third repair stringer segment sandwich the first repair stringer segment located in or adjacent to the plane. The method also includes positioning a fourth repair stringer such that the fourth repair stringer segment and the first repair stringer sandwich the second repair stringer. The method also includes connecting the first repair stringer, the second repair stringer, the third repair stringer, and the fourth repair stringer to the base stringer.

[0025]

[0025] In yet another aspect, a hat-style stringer is provided, the hat-style stringer including a stringer, the hat-style stringer also including at least one repair stringer coupled to the stringer, the repair stringer coupled to the stringer at an attachment point that is one of a plurality of possible attachment points along a cross-section of the hat-style stringer, and shaped to have an inner contour that matches at least a portion of a contour of an internal cavity defined by the hat-style stringer at each of the plurality of possible attachment points, and further comprising a cross-sectional area of ​​the repair stringer that is less than a total cross-sectional area of ​​the hat-style stringer.

[0026] So that the above-mentioned features may be more fully understood, a more particular description of the present disclosure briefly summarized above may be had by reference to exemplary embodiments, some of which are illustrated in the accompanying drawings. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a top view of an exemplary aircraft having a wing including at least one hat stringer. [Diagram 2]FIG. 2 is a cross-sectional view of a hat-shaped stringer. [Figure 3A] FIG. 1 is a cross-sectional view of a hat-style stringer undergoing a total stringer repair using a repair stringer having a "lazy Z" shape. [Figure 3B] FIG. 13 is a cross-sectional view of a hat-style stringer undergoing a total stringer repair using a repair stringer having a "lazy Z" shape. [Figure 3C] FIG. 13 is a cross-sectional view of another hat-style stringer having undergone a total stringer repair using a repair stringer having a "lazy Z" shape. [Figure 4A] FIG. 13 is a cross-sectional view of a hat-style stringer undergoing a total stringer repair using a repair stringer having a "lazy L" shape. [Figure 4B] FIG. 13 is a cross-sectional view of a hat-style stringer undergoing a total stringer repair using a repair stringer having a "lazy L" shape. [Figure 4C] FIG. 13 is a cross-sectional view of another hat-style stringer where a total stringer repair has been performed using multiple repair stringers with a "lazy Z" shape and one repair stringer with a "lazy U" shape. [Diagram 5] FIG. 1 is a cross-sectional view of a hat-style stringer having undergone a partial stringer repair. [Figure 6A] FIG. 1 is a cross-sectional view of a hat-style stringer undergoing a segment splice repair. [Figure 6B] FIG. 13 is a cross-sectional view of another hat-style stringer having a segment splice repair performed; [Figure 7] FIG. 1 is a flow diagram of a method for repairing a hat stringer according to one aspect of the present disclosure. [Figure 8] FIG. 11 is a flow diagram of a method for repairing a hat stringer according to another aspect of the present disclosure. [Figure 9] FIG. 11 is a flow diagram of a method for splicing a hat stringer according to another aspect of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028]

[0039] The present disclosure relates to repairing hat stringers. In some cases, hat stringers, which may support skin members of an aircraft, may be damaged or otherwise require structural reinforcement, for example, due to a crash event during operation. Hat stringers are sometimes removed to create space for skin repair. Presented herein, in accordance with inventive aspects of the present disclosure, are repair techniques for hat stringers and repair stringers that facilitate repairing or reinforcing hat stringers. Such repair stringers may include an internal geometry contour that matches an internal cavity contour of a stringer (e.g., of a type 1, type 2, and / or type 3 stringer). The repair stringer may be positioned such that segments of the repair stringer physically overlap one another, for example, along a cap section or a web section of the hat stringer. The inventive aspects disclosed herein advantageously allow for minimizing the total amount of parts required and eliminating or reducing the need for the use of shims. Fewer parts also reduces the weight of the aircraft, which is an advantage. Additionally, the unique geometric profile of the repair stringers disclosed herein allows for improved applicability of repair techniques to larger portions of the aircraft body and allows for easier inventorying of repair parts for airlines.

[0029]

[0040] In this disclosure, reference is made to various embodiments. However, it should be understood that the disclosure is not limited to the specific embodiments described. Instead, any combination of the following features and elements, whether related to various embodiments or not, is contemplated for implementing and practicing the teachings presented herein. In addition, when an element of an embodiment is described in the form of "at least one / one of A and B," it will be understood that an embodiment including only element A, an embodiment including only element B, and an embodiment including both element A and element B are respectively contemplated. Furthermore, while some embodiments may realize advantages over other possible approaches or the prior art, the disclosure is not limited by whether a particular advantage is achieved by a given embodiment. Thus, the embodiments, features, and advantages disclosed herein are merely exemplary and should not be considered elements of or limiting the scope of the appended claims unless expressly stated in the claims. Similarly, references to "the present invention" should not be construed as a generalization of all subject matter disclosed herein, and should not be considered an element of or as limiting the scope of the appended claims, unless expressly recited in the claims. Additionally, as used herein, a repair stringer is located primarily on a side of a hat-shaped stringer when more than fifty percent (50%) of the cross-section of the repair stringer is located on that side (as defined by the sagittal or midplane) of the hat-shaped stringer.

[0030]

[0041] While the foregoing is directed to aspects of the disclosure, other and further aspects of the disclosure may be devised without departing from the basic scope thereof, the scope of which is defined by the following claims.

[0031]

[0042] Referring now to the drawings, Figure 1 illustrates a top view of an aircraft 100 in accordance with an exemplary embodiment of the present disclosure. As illustrated, the aircraft 100 includes a pair of wings 110, 112 and a fuselage 114. The wings 110, 112 extend laterally outward from the fuselage 114. The aircraft 100 also includes a tail section 116 having a horizontal stabilizer 118 and a vertical tail 120. The wings 110, 112, horizontal stabilizer 118, and vertical tail 120 all include control surfaces 122 (e.g., ailerons, elevators, rudder, etc.) that may be controlled to steer the aircraft 100 in flight. The aircraft 100 further includes propulsion units 124, 126 mounted on the wings 110, 112, respectively. In Figure 1, the propulsion units 124, 126 are gas turbine engines configured as turbofans. However, in other exemplary embodiments, the propulsion units 124, 126 may be other types of propulsion units (such as electric fans).

[0032]

[0043] Each of the wings 110, 112 includes a skin member 128 that may be internally supported by various structures, such as stringers 130 and ribs 136 shown in the interior pictorial portion of the wing 112 in FIG. 1 . The stringers 130 are spaced apart from one another and generally extend spanwise from a root portion 132 to a tip portion 134 of each of the wings 110, 112. One or more of the stringers 130 may have a hat-shaped cross-section, for example, when viewed along the spanwise direction of the associated wing. Thus, in some example embodiments, the stringers 130 may be "hatstringers." As further shown in FIG. 1 , ribs 136 are spaced apart from one another and generally extend chordwise from a leading end structure (e.g., leading spar 138) to an aft end structure (e.g., trailing spar 140) of each of the wings 110, 112.

[0033]

[0044] FIG. 2 is a cross-sectional view of a hat stringer 200, which may be, for example, one of the hat stringers 130 of the aircraft 100 of FIG. 1. For reference, a first direction D1 (extending into and out of FIG. 2), a second direction D2, and a third direction D3 are defined. The first, second, and third directions D1, D2, D3 are perpendicular to each other and together form a rectangular coordinate system. In FIG. 2, the first direction D1 is the spanwise direction along the wing of the aircraft. Thus, FIG. 2 shows a cross-section of the hat stringer 200 as viewed along the spanwise direction of the wing. The third direction D3 may be vertical.

[0034]

[0045] As shown in FIG. 2 , the hat stringer 200 is coupled to and supports a skin panel member 202. The skin panel member 202 may be, for example, a lower wing skin of a wing. The hat stringer 130 includes a base stringer 210. The base stringer 210 may be formed of one or more plies, such as one or more carbon fiber reinforced polymer (CFRP) plies. The base stringer 210 may be formed, for example, as a monolithic one-piece structure. From left to right in FIG. 2 , the base stringer 210 includes a first flange segment 212, a first web segment 214, a cap segment 216, a second web segment 218, and a second flange segment 220. The first flange segment 212 and the second flange segment 220 are coupled to the skin panel member 202. The first web segment 214 and the second web segment 218 extend from the first flange segment 212 and the second flange segment 220, respectively, and converge toward each other as they extend away from the first flange segment 212 and the second flange segment 220. The cap segment 216 connects the first web segment 214 and the second web segment 218 and extends generally parallel to the first and second flange segments 212, 220 and the skin member 202.

[0035]

[0046] The base stringer 210 and the skin member 202 cooperate to define an internal cavity 222. An outline 224 of the internal cavity 222 is defined by the base stringer 210. In particular, the outline 224 of the internal cavity 222 is defined by an inner surface 226 of the base stringer 210 when viewed along a first direction D1 (e.g., when in a usable state). In FIG. 2, the outline 224 of the internal cavity 222 is represented by a dashed line extending along the inner surface 226 of the base stringer 210, or more specifically, along the inner surfaces of the first and second web segments 214, 218 and the cap segment 216. The outline 224 has a first web portion 224A, a cap portion 224B, and a second web portion 224C. The first web portion 224A extends along the inner surface of the first web segment 214, the cap portion 224B extends along the inner surface of the cap segment 216, and the second web portion 224C extends along the inner surface of the second web segment 218. The base stringer 210 also has an outer surface 228 opposite the inner surface 226. For further reference, the hat-shaped stringer 200 defines a midplane 230 that divides a first side 232 and a second side 234 of the hat-shaped stringer 200. The midplane 230 is perpendicular to the second direction D2.

[0036]

[0047] In some cases, a hat stringer (e.g., hat stringer 200 of FIG. 2) may be damaged or otherwise require structural reinforcement, for example, due to a crash event during operation. For example, a segment of hat stringer 200 may be damaged such that its structural integrity is compromised or, in some extreme cases, lost entirely. This may present a safety hazard or render the aircraft unfit for operation. Presented herein are repair techniques for hat stringers, and repair stringers that facilitate repair or reinforcement of hat stringers, in accordance with inventive aspects of the present disclosure. Exemplary repair techniques and repair stringers are presented below.

[0037]

[0048] 3A and 3B, which show the hat stringer 200 of FIG. 2 having undergone a total stringer repair using a repair stringer having a "lazy Z" shape. In particular, the base stringer 210 has undergone a total stringer repair process using a first repair stringer 300 and a second repair stringer 310 (both having a lazy Z shape). Both the first and second repair stringers 300, 310 may be formed of one or more plies (such as one or more carbon fiber plies). The total stringer repair may be performed in response to the base stringer 210 having been damaged or otherwise compromised in its structural integrity.

[0038]

[0049] As shown in Figures 3A and 3B, the first repair stringer 300 has a flange segment 302, a web segment 304, and a cap segment 306. The web segment 304 extends between and connects the cap segment 306 and the flange segment 302. Both the flange segment 302 and the cap segment 306 extend generally parallel to one another. The first repair stringer 300 has an inner contour 308 that matches at least a portion of the contour 224 of the internal cavity 222 defined by the hat stringer 200. In Figure 3A, the inner contour 308 of the first repair stringer 300 is represented by a dotted line extending along the inner surface of the first repair stringer 300. In other words, the inner contour 308 of the first repair stringer 300 is shaped to match or complement at least a portion of the outer surface of the stringer to which the first repair stringer 300 is adjacent. For example, as shown in FIG. 3A, the inner contour 308 of the first repair stringer 300 is shaped to match or complement at least a portion of the outer surface 228 of the base stringer 210. In addition, the cross-sectional area of ​​the first repair stringer 300, as viewed along the first direction D1 (e.g., the spanwise direction of the wing), is less than the total cross-sectional area of ​​the hat-shaped stringer 200, as viewed along the first direction D1. Thus, the first repair stringer 300 may be considered to have a partial cross-section relative to the hat-shaped stringer 200.

[0039]

[0050] The second repair stringer 310 has a flange segment 312, a web segment 314, and a cap segment 316. The web segment 314 extends between and connects the cap segment 316 and the flange segment 312. Both the flange segment 312 and the cap segment 316 extend generally parallel to one another. The second repair stringer 310, like the first repair stringer 300, has an inner contour 318 that matches at least a portion of the contour 224 of the internal cavity 222 defined by the hat stringer 200. In FIG. 3A, the inner contour 318 of the second repair stringer 310 is represented by a dotted line extending along the inner surface of the second repair stringer 310. In other words, the inner contour 318 of the second repair stringer 310 is shaped to match or complement at least a portion of the outer surface of the stringer to which the second repair stringer 310 is adjacent. For example, as shown in FIG. 3A, the inner contour 318 of the second repair stringer 310 is shaped to match or complement at least a portion of the outer surface 228 of the base stringer 210 and at least a portion of the outer surface of the first repair stringer 300. Furthermore, the cross-sectional area of ​​the second repair stringer 310, as viewed along the first direction D1, is less than the combined cross-sectional area of ​​the hat-shaped stringer 200, as viewed along the first direction D1. Thus, the second repair stringer 310 may be considered to have a partial cross-section relative to the hat-shaped stringer 200.

[0040]

[0051] 3A and 3B, the first repair stringer 300 and the second repair stringer 310 have the same cross-sectional shape when viewed along the first direction D1. The second repair stringer 310 is oriented horizontally inverted relative to the first repair stringer 300, or rather, the second repair stringer 310 is rotated one hundred and eighty degrees (180°) relative to the first repair stringer 300 about an axis of rotation that extends along the third direction D3.

[0041]

[0052] For a total stringer repair using a repair stringer having a "lazy Z" shape, the total stringer repair may be performed by positioning a first repair stringer 300 at a first attachment location along a cross section of the hat stringer 200. For example, as shown in FIG. 3A, the first repair stringer 300 is shown positioned at a first attachment location indicated by arrow 1. At the first attachment location, the first repair stringer 300 is positioned such that the flange segment 302, web segment 304, and cap segment 306 are in confront with or positioned adjacent to the first flange segment 212, first web segment 214, and cap segment 216 of the base stringer 210, respectively. When the first repair stringer 300 is placed at the first attachment location, the flange segment 302, web segment 304, and cap segment 306 of the first repair stringer 300 extend parallel to the first flange segment 212, first web segment 214, and cap segment 216 of the base stringer 210, respectively.

[0042]

[0053] Global stringer repair using a repair stringer having a "lazy Z" shape may also be performed by placing a second repair stringer 310 at a second attachment location along the cross-section of the hat stringer 200. For example, as shown in FIG. 3A, the second repair stringer 310 is shown placed at a second attachment location indicated by arrow 2. When the second repair stringer 310 is placed at the second attachment location, the flange segment 312, web segment 314, and cap segment 316 of the second repair stringer 310 extend parallel to the second flange segment 220, second web segment 218, and cap segment 216 of the base stringer 210, respectively. Further, at the second attachment location, the second repair stringer 310 is positioned such that the web segment 314 is flush with or adjacent to the second flange segment 218 of the base stringer 210, and such that the cap segment 316 is flush with or adjacent to the cap segment 306 of the first repair stringer 300. Thus, the cap segment 316 of the second repair stringer 310 physically overlaps with the cap segment 306 of the first repair stringer 300. The cap segment 306 of the first repair stringer 300 and the cap segment 316 of the second repair stringer 310 each extend parallel to the cap segment 216 of the base stringer 210. Further, as shown, the cap segment 306 of the first repair stringer 300 is sandwiched between the cap segment 316 of the second repair stringer 310 and the cap segment 216 of the base stringer 210 (e.g., along the third direction D3).

[0043]

[0054] 3A and 3B, the flange segment 312 of the second repair stringer 310 and the second flange segment 220 of the base stringer 210 are spaced apart from one another (e.g., along a third direction D3). Thus, a gap G or vertical offset is defined between the flange segment 312 of the second repair stringer 310 and the second flange segment 220 of the base stringer 210. A global stringer repair using a repair stringer having a "lazy Z" shape may further be performed by disposing one or more shims 320 between the second flange segment 220 of the base stringer 210 and the flange segment 312 of the second repair stringer 310. That is, the one or more shims 320 may be positioned to fill the gap G. For example, as shown in FIG. 3A, one or more shims 320 are shown disposed in the gap G indicated by arrow 3. The added shims 320 may improve the structural integrity of the repaired hat stringer 200. Furthermore, due to, among other things, the configuration of the first and second repair stringers 300, 310 and their placement at their respective attachment points, the need for shims on both sides of the hat stringer 200 may be eliminated or otherwise reduced. For example, in the example of FIG. 3A , no shims are needed between the flange segment 302 of the first repair stringer 300 and the first flange segment 212 of the base stringer 210.

[0044]

[0055] An overall stringer repair using a repair stringer having a "lazy Z" shape may further be performed by connecting the first repair stringer 300 and the second repair stringer 310 to the base stringer 210 at their respective attachment points. For example, as shown in FIG. 3B , a plurality of fasteners 330 may be used to connect the first and second repair stringers 300, 310 to the base stringer 210. One of the plurality of fasteners 330 may connect the flange segment 302 of the first repair stringer 300 to the first flange segment 212 of the base stringer 210. One of the plurality of fasteners 330 may connect the web segment 304 of the first repair stringer 300 to the first web segment 214 of the base stringer 210. One of the plurality of fasteners 330 may connect together the cap segment 306 of the first repair stringer 300, the cap segment 316 of the second repair stringer 310, and the cap segment 216 of the base stringer 210. One of the plurality of fasteners 330 may connect the web segment 314 of the second repair stringer 310 with the second web segment 218 of the base stringer 210. Finally, one of the plurality of fasteners 330 may connect the flange segment 312 of the second repair stringer 310 with the second flange segment 220 of the base stringer 210. Any suitable type of fastener may be utilized, including, but not limited to, rivets, bolts, screws, anchors, and the like. In alternative exemplary embodiments, the first and second repair stringers 300, 310 may be coupled to the base stringer 210 in other manners, such as by a combination of compression and heat treatment processes.

[0045]

[0056] Once the first and second repair stringers 300, 310 are connected to the base stringer 210, as shown in FIG. 3B, the hat stringer 200 may be considered a restored or repaired hat stringer.

[0046]

[0057] In particular, due at least in part to the geometric arrangement or cross-sectional shape of the first repair stringer 300, the first attachment point is one of a plurality of possible attachment points along the cross-section of the hat stringer 200 at which the first repair stringer 300 may be positioned. At each of the plurality of possible attachment points, the inner contour 308 of the first repair stringer 300 matches the contour 224 of the interior cavity 222 defined by the hat stringer 200.

[0047]

[0058] As a first exemplary alternative attachment location, the first repair stringer 300 may be positioned such that the flange segment 302, the web segment 304, and the cap segment 306 are flush with or positioned adjacent to the second flange segment 220, the second web segment 218, and the cap segment 216, respectively, of the base stringer 210. In such a first alternative attachment location, the flange segment 302, the web segment 304, and the cap segment 306 of the first repair stringer 300 may extend parallel to the second flange segment 220, the second web segment 218, and the cap segment 216, respectively, of the base stringer 210. To place the first repair stringer 300 at the first alternative attachment location, the first repair stringer 300 may be flipped horizontally relative to the orientation of the first repair stringer 300 shown in FIGS. 3A and 3B (or, rather, the first repair stringer 300 may be rotated one hundred eighty degrees (180°) from the orientation of the first repair stringer 300 shown in FIGS. 3A and 3B about an axis of rotation extending along the third direction D3). Even at the first attachment location, the inner contour 308 of the first repair stringer 300 will match the contour 224 of the internal cavity 222 defined by the hat-shaped stringer 200. Thus, the geometry of the first repair stringer 300 is shaped such that it is attachable to the hat-shaped stringer 200 at at least the first possible attachment location and the second possible attachment location. In the first possible attachment location, the first repair stringer 300 is positioned primarily on the first side 232 of the hat-shaped stringer 200 (i.e., more than fifty percent (50%) of the cross-section of the first repair stringer 300 is positioned on the first side 232), and in the second possible attachment location, the first repair stringer 300 is positioned primarily on the second side 234 of the hat-shaped stringer 200 (i.e., more than fifty percent (50%) of the cross-section of the first repair stringer 300 is positioned on the second side 234).

[0048]

[0059] As a second exemplary alternative attachment location, as shown in FIG. 3C , when the first repair stringer 300 is placed at the second alternative attachment location, the first repair stringer 300 can be positioned such that the flange segment 302, web segment 304, and cap segment 306 of the first repair stringer 300 extend parallel to, but do not contact, the first flange segment 212, first web segment 214, and cap segment 216 of the base stringer 210, respectively. Furthermore, at the second alternative attachment location, the first repair stringer 300 is positioned such that the web segment 304 is flush with or adjacent to the first web segment of another repair stringer 340 (e.g., the first existing repair stringer) and the cap segment 306 is flush with or adjacent to the cap segment of yet another repair stringer 350 (e.g., the second existing repair stringer). Thus, the cap segment 306 of the first repair stringer 300 physically overlaps with, for example, the cap segment of the second existing repair stringer 350. At the second alternative attachment location, the inner contour 308 of the first repair stringer 300 will also match the contour 224 of the interior cavity 222 defined by the hat stringer 200. Thus, the geometry of the first repair stringer 300 is shaped such that the first repair stringer 300 can be attached to the hat-shaped stringer 200 at an attachment point where the first repair stringer 300 is layered over another stringer other than the base stringer 210 (e.g., an existing repair stringer).

[0049]

[0060] As a third exemplary alternative attachment location, the first repair stringer 300 may be located at the second attachment location (or rather, the attachment location where the second repair stringer 310 is located in FIGS. 3A and 3B ), and the second repair stringer 310 may be attached to another of the multiple possible attachment locations. Thus, as will be appreciated from the teachings above, the second repair stringer 310, like the first repair stringer 300, may similarly be attachable to multiple possible locations.

[0050]

[0061] In some exemplary embodiments, at each of a plurality of possible attachment locations where the first repair stringer 300 may be attached, the web segment 304 of the first repair stringer 300 runs parallel to the web segment of the base stringer 210. In other words, in some exemplary embodiments, at each of a plurality of possible attachment locations where the first repair stringer 300 may be attached, the inner surface of the web segment 304 of the first repair stringer 300 runs parallel to the web portion of the contour 224. The same is true for the second repair stringer 310. That is, at each of a plurality of possible attachment locations where the second repair stringer 310 may be attached, the web segment 314 of the second repair stringer 310 runs parallel to the web segment of the base stringer 210. In other words, in some exemplary embodiments, at each of a plurality of possible attachment locations where the second repair stringer 310 may be attached, the inner surface of the web segment 314 of the second repair stringer 310 extends parallel to the web portion of the contour 224.

[0051]

[0062] In yet another exemplary embodiment, at each of a plurality of possible attachment locations to which the first repair stringer 300 may be attached, the cap segment 306 of the first repair stringer 300 extends parallel to the cap segment 216 of the base stringer 210, and the flange segment 302 of the first repair stringer 300 extends parallel to the flange segment of the base stringer 210. The same is true for the second repair stringer 310. Specifically, at each of a plurality of possible attachment locations to which the second repair stringer 310 may be attached, the cap segment 316 of the second repair stringer 310 extends parallel to the cap segment 216 of the base stringer 210, and the flange segment 312 of the second repair stringer 310 extends parallel to the flange segment of the base stringer 210.

[0052]

[0063] Repairing a hat stringer with one or more repair stringers, each having a lazy Z cross-sectional shape, may provide certain advantages. For example, the lazy Z cross-sectional shape of the part allows the repair stringer to be attached at multiple attachment points along the cross-section of the hat stringer, thereby providing flexibility in the repair process. Additionally, the repair may require less shims compared to conventional techniques. For example, in FIG. 3B, the flange segment 302 of the first repair stringer 300 may be positioned directly above or adjacent to the first flange segment 212 of the base stringer 210, such that a shim 320 is required on only one side of the hat stringer. Additionally, the repair stringer having a lazy Z cross-sectional shape includes three segments that may contact three corresponding segments of one or more other stringers. This three-point contact may provide structural stability to the repaired hat stringer. Additionally, repairing a hat stringer with multiple lazy Z-shaped repair stringers has the advantage that the repair stringers may be overlapped on the hat stringer without requiring changes in shape or angle (e.g., as shown in FIG. 3C), which may eliminate or greatly reduce the need for individually adapted repair stringers for overlapping arrangements. In other words, multiple identically shaped lazy Z-shaped repair stringers may be used for overlap repairs. This advantage may improve the ease with which workers can perform the repair process, and stack, inventory repair parts, etc.

[0053]

[0064] 4A and 4B, which show the hat-style stringer 200 of FIG. 2 having been subjected to a full stringer repair using repair stringers having a "lazy L" shape. In particular, the base stringer 210 has been subjected to a full stringer repair process using a first repair stringer 400, a second repair stringer 410, a third repair stringer 420, and a fourth repair stringer 430 (all having a lazy L shape or, rather, a lazy L cross-section when viewed along a first direction D1). The first, second, third, and fourth repair stringers 400, 410, 420, 430 may each be formed of one or more plies (such as one or more carbon fiber plies). A full stringer repair may be performed in response to the base stringer 210 being damaged or the structural integrity of the base stringer 210 being otherwise compromised.

[0054]

[0065] As shown in Figures 4A and 4B, the first, second, third, and fourth repair stringers 400, 410, 420, 430 generally each include a web segment and a second segment, which may be a flange segment or a cap segment depending on the orientation of the repair stringer. The second segment of a given repair stringer is non-parallel to its web segment. An obtuse angle is defined between the web segment and the second segment of each of the first, second, third, and fourth repair stringers 400, 410, 420, 430. In particular, as shown, the first repair stringer 400 has a web segment 404 and a second segment, which in this example is a flange segment 402. The second repair stringer 410 includes a web segment 414 and a second segment, which in this example is a flange segment 416. The third repair stringer 420 includes a web segment 424 and a second segment, which in this example is a flange segment 422. The fourth repair stringer 430 includes a web segment 434 and a second segment, which in this example is a cap segment 436.

[0055]

[0066] The first repair stringer 400 has an inner contour 408 that matches at least a portion of the contour 224 of the internal cavity 222 defined by the hat stringer 200. In FIG. 4A , the inner contour 408 of the first repair stringer 400 is represented by a dashed line extending along the inner surface of the first repair stringer 400. As shown, the inner contour 408 of the first repair stringer 400 is shaped to match or complement at least a portion of the first web portion 224A of the contour 224. In other words, the inner contour 408 of the first repair stringer 400 is shaped to match or complement at least a portion of the outer surface of the stringer or stringers to which the first repair stringer 400 is positioned adjacent. For example, as shown in FIG. 4A , the inner contour 408 of the first repair stringer 400 is shaped to match or complement at least a portion of the outer surface 228 of the base stringer 210.

[0056]

[0067] The second repair stringer 410 has an inner contour 418 that matches at least a portion of the contour 224 of the internal cavity 222 defined by the hat stringer 200. In FIG. 4A, the inner contour 418 of the second repair stringer 410 is represented by a dashed line extending along the inner surface of the second repair stringer 410. As shown, the inner contour 418 of the second repair stringer 410 is shaped to match or complement at least a portion of the first web portion 224A and the cap portion 224B of the contour 224. In other words, the inner contour 418 of the second repair stringer 410 is shaped to match or complement at least a portion of the outer surface of the stringer or stringers to which the second repair stringer 410 is disposed adjacent. For example, as shown in FIG. 4A , the inner contour 418 of the second repair stringer 410 is shaped to match or complement at least a portion of the outer surface 228 along the cap segment 216 of the base stringer 210 and at least a portion of the outer surface of the first repair stringer 400.

[0057]

[0068] The third repair stringer 420 has an inner contour 428 that matches at least a portion of the contour 224 of the internal cavity 222 defined by the hat stringer 200. In FIG. 4A , the inner contour 428 of the third repair stringer 420 is represented by a dashed line extending along the inner surface of the third repair stringer 420. As shown, the inner contour 428 of the third repair stringer 420 is shaped to match or complement at least a portion of the second web portion 224C of the contour 224. In other words, the inner contour 428 of the third repair stringer 420 is shaped to match or complement at least a portion of the outer surface of the stringer or stringers to which the third repair stringer 420 is disposed adjacent. For example, as shown in FIG. 4A , the inner contour 428 of the third repair stringer 420 is shaped to match or complement at least a portion of the outer surface 228 of the base stringer 210.

[0058]

[0069] The fourth repair stringer 430 has an inner contour 438 that matches at least a portion of the contour 224 of the internal cavity 222 defined by the hat stringer 200. In FIG. 4A, the inner contour 438 of the fourth repair stringer 430 is represented by a dashed line extending along the inner surface of the fourth repair stringer 430. As shown, the inner contour 438 of the fourth repair stringer 430 is shaped to match or complement at least a portion of the second web portion 224C and the cap portion 224B of the contour 224. In other words, the inner contour 438 of the fourth repair stringer 430 is shaped to match or complement at least a portion of the outer surface of the stringer or stringers to which the fourth repair stringer 430 is disposed adjacent. For example, as shown in FIG. 4A , the inner contour 438 of the fourth repair stringer 430 is shaped to match or complement at least a portion of the outer surface of the third repair stringer 420 and at least a portion of the outer surface of the second repair stringer 410.

[0059]

[0070] 4A and 4B, the cross-sectional area of ​​the first repair stringer 400, when viewed along the first direction D1 (e.g., the spanwise direction of the wing), is less than the combined cross-sectional area of ​​the hat-shaped stringer 200, when viewed along the first direction D1. The same is true for the second, third, and fourth repair stringers 410, 420, 430. Thus, the first, second, third, and fourth repair stringers 400, 410, 420, 430 may each be considered to have a partial cross-section relative to the hat-shaped stringer 200.

[0060]

[0071] 4A and 4B, the first, second, third, and fourth repair stringers 400, 410, 420, 430 may each have the same cross-sectional shape as one another when viewed along the first direction D1. In FIGURES 4A and 4B, the second repair stringer 410 is oriented vertically inverted relative to the first repair stringer 400, or rather, the second repair stringer 410 is rotated one hundred and eighty degrees (180°) relative to the first repair stringer 400 about an axis of rotation that extends along the second direction D2. The third repair stringer 420 is oriented in a horizontal flip relative to the first repair stringer 400, or rather, the third repair stringer 420 is rotated one hundred eighty degrees (180°) about an axis of rotation extending along the third direction D3 relative to the first repair stringer 400. The fourth repair stringer 430 is oriented in a vertical and horizontal flip relative to the first repair stringer 400, or rather, the fourth repair stringer 430 is rotated one hundred eighty degrees (180°) about an axis of rotation extending along the third direction D3 relative to the first repair stringer 400 for its horizontal flip, and rotated one hundred eighty degrees (180°) about an axis of rotation extending along the second direction D2 relative to the first repair stringer 400 for its vertical flip.

[0061]

[0072] For a total stringer repair using a repair stringer having a "lazy L" shape, the total stringer repair may be performed by positioning a first repair stringer 400 at a first attachment location along the cross section of the hat stringer 200. For example, as shown in FIG. 4A, the first repair stringer 400 is shown positioned at a first attachment location indicated by arrow 1. At the first attachment location, the first repair stringer 400 is positioned such that its flange segment 402 and web segment 404 are flush with or positioned adjacent to the first flange segment 212 and first web segment 214 of the base stringer 210, respectively. When the first repair stringer 400 is placed at the first attachment location, the flange segment 402 and web segment 404 of the first repair stringer 400 extend parallel to the first flange segment 212 and the first web segment 214 of the base stringer 210, respectively.

[0062]

[0073] Global stringer repair using a repair stringer having a "lazy L" shape may further be performed by positioning a second repair stringer 410 at a second attachment location along the cross-section of the hat stringer 200. For example, as shown in FIG. 4A, the second repair stringer 410 is shown positioned at a second attachment location indicated by arrow 2. At the second attachment location, the second repair stringer 410 is positioned such that the web segment 414 and cap segment 416 of the second repair stringer 410 extend parallel to the first web segment 214 and cap segment 216 of the base stringer 210, respectively. Furthermore, at the second attachment location, the second repair stringer 410 is positioned such that its web segment 414 is flush with or positioned adjacent to the web segment 404 of the first repair stringer 400. Thus, the web segment 414 of the second repair stringer 410 physically overlaps the web segment 404 of the first repair stringer 400, with the web segment 404 sandwiched or positioned between the web segment 414 and the first web segment 214 of the base stringer 210. Further, at the second attachment location, the second repair stringer 410 is positioned such that its cap segment 416 is flush with or positioned adjacent to the cap segment 216 of the base stringer 210.

[0063]

[0074] Global stringer repair using a repair stringer having a "lazy L" shape may also be performed by placing a third repair stringer 420 at a third attachment location along the cross-section of the hat stringer 200. For example, as shown in FIG. 4A, the third repair stringer 420 is shown placed at a third attachment location indicated by arrow 3. At the third attachment location, the third repair stringer 420 is positioned such that its flange segment 422 and web segment 424 are flush with or positioned adjacent to the second flange segment 220 and second web segment 218, respectively, of the base stringer 210. When the third repair stringer 420 is placed at the third attachment location, the flange segment 422 and web segment 424 of the third repair stringer 420 extend parallel to the second flange segment 220 and second web segment 218, respectively, of the base stringer 210.

[0064]

[0075] A global stringer repair using a repair stringer having a "lazy L" shape may further be performed by positioning a fourth repair stringer 430 at a fourth attachment location along the cross-section of the hat stringer 200. For example, as shown in FIG. 4A, the fourth repair stringer 430 is shown positioned at a fourth attachment location indicated by arrow 4. At the fourth attachment location, the fourth repair stringer 430 is positioned such that the web segment 434 and the cap segment 436 of the fourth repair stringer 430 extend parallel to the second web segment 218 and the cap segment 216 of the base stringer 210, respectively. Additionally, at the fourth attachment location, the fourth repair stringer 430 is positioned such that its web segment 434 is flush with or adjacent to the web segment 424 of the third repair stringer 420. Thus, the web segment 434 of the fourth repair stringer 430 physically overlaps the web segment 424 of the third repair stringer 420, with the web segment 424 sandwiched or positioned between the web segment 434 and the second web segment 218 of the base stringer 210. Further, at the fourth attachment location, the fourth repair stringer 430 is positioned such that its cap segment 436 is flush with or positioned adjacent to the cap segment 416 of the second repair stringer 410. The cap segment 436 of the fourth repair stringer 430 is spaced from the cap stringer 216 of the base stringer 210, for example along the third direction D3.

[0065]

[0076] An overall stringer repair using repair stringers having a "lazy L" shape may further be performed by connecting the first, second, third, and fourth repair stringers 400, 410, 420, 430 to the base stringer 210 at their respective attachment points. For example, as shown in FIG. 4B , a plurality of fasteners 440 may be used to connect the first, second, third, and fourth repair stringers 400, 410, 420, 430 to the base stringer 210. One of the plurality of fasteners 440 may connect the flange segment 402 of the first repair stringer 400 to the first flange segment 212 of the base stringer 210. One of the plurality of fasteners 440 may connect the web segment 404 of the first repair stringer 400, the web segment 414 of the second repair stringer 410, and the first web segment 214 of the base stringer 210. One of the plurality of fasteners 440 may connect the cap segment 416 of the second repair stringer 410, the cap segment 436 of the third repair stringer 420, and the cap segment 216 of the base stringer 210. One of the plurality of fasteners 440 may connect the web segment 424 of the third repair stringer 420, the web segment 434 of the fourth repair stringer 430, and the second web segment 218 of the base stringer 210. Finally, one of a plurality of fasteners 440 may connect the flange segment 422 of the third repair stringer 420 to the second flange segment 220 of the base stringer 210. Any suitable type of fastener may be utilized, including but not limited to rivets, bolts, screws, anchors, etc. In alternative exemplary embodiments, the first, second, third and / or fourth repair stringers 400, 410, 420, 430 may be connected to the base stringer 210 in other manners (e.g., by a combination of compression and heat treatment processes).

[0066]

[0077] Once the first, second, third, and fourth repair stringers 400, 410, 420, 430 are connected to the base stringer 210, as shown in FIG. 4B, the hat stringer 200 may be considered a restored or repaired hat stringer.

[0067]

[0078] In particular, due at least in part to the geometric arrangement or cross-sectional shape of the first repair stringer 400, the first attachment point is one of a plurality of possible attachment points along the cross-section of the hat stringer 200 at which the first repair stringer 400 may be positioned. At each of the plurality of possible attachment points, the inner contour 408 of the first repair stringer 400 matches at least a portion of the contour 224 of the interior cavity 222 defined by the hat stringer 200. For example, first repair stringer 400 may be flipped vertically and / or horizontally to be attached to any one of the attachment points shown in Figures 4A and 4B for the second, third, and / or fourth repair stringers, as well as any other possible attachment points, with the inner contour of first repair stringer 400 shaped to match or complement at least a portion of contour 224 of internal cavity 222. The same is true for second repair stringer 410, third repair stringer 420, and fourth repair stringer 430. In this manner, each of the first, second, third and fourth repair stringers 400 , 410 , 420 , 430 can be attached to a plurality of attachment points along the cross section of the hat-shaped stringer 200 .

[0068]

[0079] Repairing a hat stringer with one or more repair stringers, each having a lazy L cross-sectional shape, may provide certain advantages. For example, the lazy L cross-section may allow the repair stringer to be attached at multiple attachment points along the cross-section of the hat stringer, thereby providing flexibility in the repair process. Additionally, the need for shims in the repair may be eliminated or otherwise significantly reduced. For example, in FIG. 4B, no shims are required to repair the hat stringer. Additionally, the repair stringer having a lazy L cross-sectional shape includes two segments that may contact two corresponding segments of one or more other stringers. This two-point contact may provide structural stability to the repaired hat stringer. Additionally, repairing hat stringers with multiple lazy-L shaped repair stringers has the advantage that such hat stringers may be stacked without requiring modification of the shape or angle of the repair stringers, which may eliminate or greatly reduce the need for custom repair stringers for stacking arrangements, which may improve the ease with which workers can perform the repair process, stack, inventory repair parts, etc.

[0069]

[0080] 4C is a cross-sectional view of another hat-shaped stringer in which a total stringer repair has been performed using multiple repair stringers with a "lazy Z" shape and one repair stringer with a "lazy U" shape. In particular, the base stringer 210 has been subjected to a total stringer repair process using a first repair stringer 400, a second repair stringer 420 (configured and oriented similarly to the third repair stringer 420 of FIGS. 4A and 4B), and a third repair stringer 450. Both the first and second repair stringers 400, 420 have a lazy L shape, or rather a lazy L cross-section, when viewed along the first direction D1. The third repair stringer 450 has a lazy U shape, or rather a lazy U cross-section, when viewed along the first direction D1. The third repair stringer 450 may be positioned in an upward orientation, for example, as shown in Figure 4C, or in an upside-down lazy U. The first, second, and third repair stringers 400, 420, 450 may each be formed of one or more plies (such as one or more carbon fiber plies). A total stringer repair may be performed in response to the base stringer 210 being damaged or otherwise compromising the structural integrity of the base stringer 210.

[0070]

[0081] The first and second repair stringers 400, 420 may be positioned as described above with reference to Figures 4A and 4B. The third repair stringer 450 includes a first web segment 454, a cap segment 456, and a second web segment 458. The cap segment 456 extends between and connects the first web segment 454 and the second web segment 458. A first obtuse angle is defined between the first web segment 454 and the cap segment 456. A second obtuse angle is defined between the second web segment 458 and the cap segment 456. In Figure 4C, the third repair stringer 450 does not include a flange segment.

[0071]

[0082] The third repair stringer 450 has an inner contour 460 that matches at least a portion of the contour 224 of the internal cavity 222 defined by the hat stringer 200. In FIG. 4C, the inner contour 460 of the third repair stringer 450 is represented by a dashed line extending along the inner surface of the third repair stringer 450. As shown, the inner contour 460 of the third repair stringer 450 is shaped to match or complement the first web portion 224A, the cap portion 224B, and the second web portion 224C of the contour 224. In other words, the inner contour 460 of the third repair stringer 450 is shaped to match or complement the outer surface of the stringer or stringers to which the third repair stringer 450 is disposed adjacent. For example, as shown in FIG. 4C , the inner contour 460 of the third repair stringer 450 is shaped to match or complement at least a portion of the outer surface of the first repair stringer 400, at least a portion of the outer surface of the baseline stringer 210, and at least a portion of the outer surface of the second repair stringer 420.

[0072]

[0083] Thus, a repair stringer having a lazy U shape may be arranged such that its first web segment is connected to one repair stringer web segment, its cap segment is connected to and spans the entire length of the baseline stringer cap segment, and its second web segment is connected to another repair stringer web segment, which may provide advantageous structural integrity, etc., in the repaired hat stringer cap and web segments.

[0073]

[0084] Referring now to FIG. 5, FIG. 5 illustrates the hat stringer 200 of FIG. 2 having undergone a partial stringer repair using at least one repair stringer having a "lazy L" shape. In particular, the base stringer 210 has undergone a process of partial stringer repair using a single repair stringer (first repair stringer 500 in this example) having a lazy L shape or rather a lazy L cross-section when viewed along a first direction D1. The first repair stringer 500 may be formed of one or more plies (such as one or more carbon fiber plies). The partial stringer repair may be performed in response to the base stringer 210 having been damaged (e.g., as represented by damaged portion 204 in FIG. 5) or the structural integrity of the base stringer 210 having otherwise been compromised. The damaged portion 204, in this example, is located at the transition between the first flange segment 212 and the first web segment 214, but in other examples, may be located at another area along the cross-section of the hat stringer 200. Additionally, in some alternative exemplary embodiments, a repair stringer having a "lazy Z" shape may be used for partial stringer repair.

[0074]

[0085] As shown in FIG. 5, the first repair stringer 500 includes a first segment (e.g., a web segment) and a second segment, which may be a flange segment or a cap segment depending on the orientation of the first repair stringer 500, similar to the repair stringers 400, 410, 420, 430 of FIGS. 4A and 4B. The second segment of the first repair stringer 500 is non-parallel to the first segment. An obtuse angle is defined between the first and second segments of the first repair stringer 500. In the example of FIG. 5, the first segment of the first repair stringer 500 is a web segment 504, and the second segment is a flange segment 502.

[0075]

[0086] The first repair stringer 500 has an inner contour 508 that matches at least a portion of the contour 224 of the internal cavity 222 defined by the hat stringer 200. In FIG. 5 , the inner contour 508 of the first repair stringer 500 is represented by a dotted line extending along the inner surface of the first repair stringer 500. As shown, the inner contour 508 of the first repair stringer 500 is shaped to match or complement at least a portion of the first web portion 224A of the contour 224. In other words, the inner contour 508 of the first repair stringer 500 is shaped to match or complement at least a portion of the outer surface of the stringer or stringers to which the first repair stringer 500 is positioned adjacent. For example, as shown in Figure 5, the inner contour 508 of the first repair stringer 500 is shaped to match or complement at least a portion of the outer surface 228 of the base stringer 210. Additionally, in the example shown in Figure 5, the cross-sectional area of ​​the first repair stringer 500 when viewed along the first direction D1 (e.g., the spanwise direction of the wing) is less than the combined cross-sectional area of ​​the hat stringers 200 when viewed along the first direction D1.

[0076]

[0087] For partial stringer repair using a repair stringer having a "lazy L" shape, the partial stringer repair may be performed by positioning a first repair stringer 500 at a first attachment location along the cross-section of the hat stringer 200. For example, as shown in FIG. 5, the first repair stringer 500 is shown positioned at a first attachment location indicated by arrow 1. At the first attachment location, the first repair stringer 500 is positioned such that its flange segment 502 and web segment 504 are flush with or positioned adjacent to the first flange segment 212 and first web segment 214 of the base stringer 210, respectively. When the first repair stringer 500 is placed at the first attachment location, the flange segment 502 and web segment 504 of the first repair stringer 500 extend parallel to the first flange segment 212 and the first web segment 214 of the base stringer 210, respectively.

[0077]

[0088] A partial stringer repair using a repair stringer having a "lazy L" shape may further be performed by connecting a first repair stringer 500 to a base stringer 210 at a first attachment point. For example, as shown in FIG. 5, a plurality of fasteners 520 may be used to connect the first repair stringer 500 to the base stringer 210. One of the plurality of fasteners 520 may connect a flange segment 502 of the first repair stringer 500 to a first flange segment 212 of the base stringer 210. One of the plurality of fasteners 520 may connect a web segment 504 of the first repair stringer 500 to a first web segment 214 of the base stringer 210. Any suitable type of fastener may be utilized, including, but not limited to, rivets, bolts, screws, anchors, and the like. In alternative exemplary embodiments, the first repair stringer 500 may be coupled to the base stringer 210 in other manners (e.g., by a combination of compression and heat treatment processes). Once the first repair stringer 500 is coupled to the base stringer 210 as shown in FIG. 5, the hat stringer 200 may be considered a restored or repaired hat stringer.

[0078]

[0089] In particular, due at least in part to the geometric arrangement or cross-sectional shape of the first repair stringer 500, the first attachment point is one of a plurality of possible attachment points along the cross-section of the hat stringer 200 at which the first repair stringer 500 may be positioned. At each of the plurality of possible attachment points, the inner contour 508 of the first repair stringer 500 matches at least a portion of the contour 224 of the internal cavity 222 of the hat stringer 200. The first repair stringer 500 may be positioned vertically and / or horizontally inverted at another possible attachment point.

[0079]

[0090] As an example, to repair damage to the transition between, for example, the second web segment 218 and the second flange segment 220 of the base stringer 210, the first repair stringer 500 may be flipped horizontally so that the web segment 504 and the flange segment 502 are aligned with the second web segment 218 and the second flange segment 220 of the base stringer 210, respectively. As another example, to repair damage to the transition between, for example, the first web segment 214 and the cap segment 216 of the base stringer 210, the first repair stringer 500 may be flipped vertically so that the web segment 504 and the second segment are aligned with the first web segment 214 and the cap segment 216 of the base stringer 210, respectively. As yet another example, to repair damage to the transition between the second web segment 218 and the cap segment 216 of the base stringer 210, for example, the first repair stringer 500 may be flipped both vertically and horizontally and positioned such that the web segment 504 and its second segment are aligned with the second web segment 218 and the cap segment 216 of the base stringer 210, respectively. In any of the possible attachment locations, the inner contour of the first repair stringer 500 matches or complements at least a portion of the contour 224 of the internal cavity 222.

[0080]

[0091] Hat-style partial stringer repair using the repair stringers disclosed herein may provide certain advantages by having such repair stringers have a lazy L or Z cross-sectional shape. For example, the repair stringers disclosed herein have a partial cross-section relative to the total cross-section of the hat stringer, which allows the repair stringers to be strategically and centrally located at the damaged sections of the hat stringer. This may also reduce the material used in the repair, which may advantageously reduce the weight of the aircraft.

[0081]

[0092] 6A, which illustrates the hat stringer 200 of FIG. 2 undergoing a splice repair using repair stringers having a "lazy L" shape. In particular, the process of splice repair is performed on the base stringer 210 with a plurality of strategically placed and oriented repair stringers, including a first set 600 of repair stringers located primarily on the first side 232 of the hat stringer 200 as needed for the splice repair, and a second set 602 of repair stringers located primarily on the second side 234. The first set 600 includes a first repair stringer 610, a second repair stringer 620, a third repair stringer 630, and a fourth repair stringer 640. Regardless of their respective mounting positions or orientations, the first, second, third, and fourth repair stringers 610, 620, 630, 640 are each shaped to have an inner contour that matches at least a portion of the contour 224 of the interior cavity 222 defined by the hat stringer 200. In some aspects, the first, second, third, and fourth repair stringers 610, 620, 630, 640 all have the same cross-sectional shape as one another, for example, when viewed along a first direction D1 (which may be a spanwise direction along the aircraft wing).

[0082]

[0093] The second set 602 includes a first repair stringer 650, a second repair stringer 660, a third repair stringer 670, and a fourth repair stringer 680. The repair stringers 610, 620, 630, 640, 650, 660, 670, 680 (i.e., 610-680) may each be formed of one or more plies (such as one or more carbon fiber plies). Regardless of their respective mounting positions or orientations, the first, second, third, and fourth repair stringers 650, 660, 670, 680 are each shaped to have an inner contour that matches at least a portion of the contour 224 of the interior cavity 222 defined by the hat stringer 200. In some aspects, the first, second, third, and fourth repair stringers 650, 660, 670, 680 all have the same cross-sectional shape as one another, for example, when viewed along a first direction D1 (which may be a spanwise direction along the wing of the aircraft).

[0083]

[0094] A splice repair may be performed in response to a base stringer 210 being damaged with a missing section (e.g., missing section 206 shown in FIG. 6A). In the example of FIG. 6A, a first web segment, a cap segment, and a second web segment of the base stringer 210 are missing, thus collectively forming the missing section 206 or chip of the base stringer 210. A plane 208 may be defined where the missing section 206 of the base stringer 210 was previously located. The plane 208 is shown in FIG. 6A as a dotted line.

[0084]

[0095] In a splice repair using repair stringers having a "lazy L" shape, the splice repair may be performed by constructing a first set of repair stringers 600. In particular, constructing the first set 600 may include positioning the first repair stringer 610 such that a segment of the first repair stringer 610 (e.g., web segment 614) is positioned at or adjacent to the plane 208 in which the missing section 206 of the base stringer 210 was previously located. In FIG. 6A , the web segment 614 of the first repair stringer 610 is positioned at least partially in the plane 208 in which the first web segment of the base stringer 210 was previously located.

[0085]

[0096] Constructing the first set 600 further includes positioning the second repair stringer 620 and the third repair stringer 630 such that the segments of the second repair stringer 620 and the third repair stringer 630 (e.g., web segment 624 of the second repair stringer 620 and web segment 634 of the third repair stringer 630) sandwich a segment of the first repair stringer 610 (e.g., web segment 614) positioned in the plane 208. As shown in FIG. 6A , the third repair stringer 630 has a flange segment 632 that is flush with or positioned adjacent to the first flange segment 212 of the base stringer 210. The second repair stringer 620 has a flange segment 622 that is flush with or positioned adjacent to a flange segment 632 of a third repair stringer 630. The flange segments 622, 632 are positioned relative to the first flange segment 212 such that a space or gap is defined between the web segments 624, 634. The gap between the web segments 624, 634 is sized to receive the web segment 614 of the first repair stringer 610, or rather, such that the web segment 614 is sandwiched between the web segments 624, 634. Positioning the web segment 614 between the web segments 624, 634 may advantageously improve the structural integrity of the hat stringer 200.

[0086]

[0097] Assembling the first set of repair stringers 600 along the first side 232 may further include positioning the fourth repair stringer 640 such that a segment of the fourth repair stringer 640 (e.g., web segment 644) and a segment of the first repair stringer 610 (e.g., web segment 614) sandwich the second repair stringer 620 (e.g., web segment 624). As shown in FIG. 6A, the first repair stringer 610 and the fourth repair stringer 640 are positioned to define a space or gap between their respective web segments 614, 644. The gap between the web segments 614, 644 is sized such that the web segment 624 of the second repair stringer 620 may be received therein, or rather, such that the web segment 624 may be sandwiched between the web segments 614, 644. The web segment 624 between the web segments 614 , 644 may advantageously improve the structural integrity of the hat stringer 200 .

[0087]

[0098] 6A , with the first, second, third, and fourth repair stringers 610, 620, 630, 640 positioned as described above, the second and third repair stringers 620, 630 have the same mounting orientation, and the first and fourth repair stringers 610, 640 have the same mounting orientation. As shown, the second and third repair stringers 620, 630 are oriented inverted vertically and horizontally relative to the first and fourth repair stringers 610, 640.

[0088]

[0099] Assembling the first set of repair stringers 600 along the first side 232 may further include coupling the first, second, third, and fourth repair stringers 610, 620, 630, 640 to the base stringer 210. For example, as shown in FIG. 6A , a plurality of fasteners 690 are used to couple the first, second, third, and fourth repair stringers 610, 620, 630, 640 of the first set 600 to the base stringer 210. One of the plurality of fasteners 690 may couple the flange segment 622 of the second repair stringer 620 and the flange segment 632 of the third repair stringer 630 to the first flange segment 212 of the base stringer 210. One of the plurality of fasteners 690 may connect the web segments 614, 624, 634, 644 of the first, second, third, and fourth repair stringers 610, 620, 630, 640. The first and fourth repair stringers 610, 640 are connected to the second and third repair stringers 620, 630 which are connected to the base stringer 210, and therefore also to the base stringer 210. Any suitable type of fastener may be utilized, including, but not limited to, rivets, bolts, screws, anchors, and the like. In alternative exemplary embodiments, the first, second, third, and / or fourth repair stringers 610, 620, 630, 640 of the first set 600 may be connected to the base stringer 210 in other manners (e.g., by a combination of compression and heat treatment processes).

[0089]

[0100] When the first, second, third, and fourth repair stringers 610, 620, 630, 640 of the first set 600 are in position and connected to the base stringer 210, the first set 600 can be considered to be repairing a first portion of the first web segment and cap segment of the base stringer 210.

[0090]

[0101] Further, the splice repair may be performed by assembling the second set of repair stringers 602. In particular, the second set of repair stringers 602 may include positioning the first, second, third, and / or fourth repair stringers 650, 660, 670, 680 relative to the first set 600 as described above, and further coupling them to the base stringer 210 (e.g., the second flange segment 220 of the base stringer 210).

[0091]

[0102] When the first and fourth repair stringers 610, 640 of the first set 600 are positioned as described above, a gap is defined between their respective cap segments 616, 646. In the example of FIG. 6A, the gap defined between the cap segments 616, 646 is located in the plane 208 where the missing section 206 of the base stringer 210 was previously located. The gap is sized to be capable of receiving (e.g., along the third direction D3) another repair stringer (e.g., in FIG. 6A, the cap segment 656 of the first repair stringer 650 of the second set 602). Furthermore, when the first repair stringer 650 and the fourth repair stringer 680 of the second set 602 are positioned as described above, a gap is defined between their respective cap segments 656, 686. In the example of Figure 6A, the gap defined between the cap segments 616, 646 is disposed in the plane 208 where the missing section 206 of the base stringer 210 previously located. The gap is sized to be capable of receiving (e.g., along the third direction D3) another repair stringer (e.g., in Figure 6A, the cap segment 646 of the fourth repair stringer 640 of the first set 600).

[0092]

[0103] 6A , an inner surface of the cap segment 686 of the fourth repair stringer 680 of the second set 602 is flush with or positioned adjacent to an outer surface 646 of the fourth repair stringer 640 of the first set 600. Thus, the cap segment 686 of the fourth repair stringer 680 of the second set 602 physically overlaps with the cap segment 646 of the fourth repair stringer 640 of the first set 600. The cap segment 646 of the fourth repair stringer 640 of the first set 600 physically overlaps with the cap segment 656 of the first repair stringer 650 of the second set 602. The cap segment 656 of the first repair stringer 650 of the second set 602 physically overlaps with the cap segment 616 of the first repair stringer 610 of the first set 600.

[0093]

[0104] 6A , the cap segments 616, 656, 646, 686 of each of the repair stringers 610, 650, 640, 680 extend from their respective major sides across the mid-plane 230. For example, the first repair stringer 610 is positioned primarily on the first side 232 of the hat-shaped stringer 200, while an end of the cap segment 616 extends across the mid-plane 230 to the second side 234. The first repair stringer 650 is positioned primarily on the second side 234 of the hat-shaped stringer 200, while an end of the cap segment 656 extends across the mid-plane 230 to the first side 232. Similarly, the fourth repair stringer 640 is positioned primarily on the first side 232 of the hat stringer 200, but an end of the cap segment 646 extends across the mid-plane 230 to the second side 234. The fourth repair stringer 680 is positioned primarily on the second side 234 of the hat stringer 200, but an end of the cap segment 686 extends across the mid-plane 230 to the first side 232. One of a number of fasteners 690 may connect the cap segments 616, 656, 646, 686, thereby connecting the first set 600 with the second set 602, as shown in FIG. 6A .

[0094]

[0105] With the first, second, third, and fourth repair stringers 650, 660, 670, 680 of the second set 602 in place and coupled to the base stringer 210, the second set 602 may be considered to be repairing the second web segment and a second portion of the cap segment of the base stringer 210. With the first and second sets 600, 602 coupled as described above, the first flange segment 212 and the second flange segment 220 are spliced ​​together and the splice repair may be considered to be complete.

[0095]

[0106] In some further exemplary embodiments, a hat stringer may have a splice repair performed using only a single set of repair stringers (e.g., a set of "lazy Z" repair stringers). For example, and referring briefly to FIG. 6B, a first set of repair stringers 600 is shown utilized to repair a first web segment and a portion of the cap segment 216 that are missing from the cross-section of the hat stringer 200. In this example, the base stringer 210 is not damaged or otherwise compromised in its structural integrity. Thus, in the example of FIG. 6B, a second set of repair stringers (e.g., second set 602 of FIG. 6A) is not required to complete the splice repair.

[0096]

[0107] In yet another exemplary embodiment, a full repair, partial repair, or splice repair may be performed using hat stringers, at least one lazy Z-shaped repair stringer, and at least one lazy L-shaped repair stringer.

[0097]

[0108] In some exemplary aspects, a repair stringer is provided that may be used to repair or restore a hat stringer according to any of the techniques disclosed herein. The repair stringer may include a web segment. The web segment has an inner contour shaped to match a web portion of the contour of the interior cavity defined by the hat stringer. The repair stringer may further include at least one of a cap segment and a flange segment extending from the web segment. The repair stringer may have a partial cross section relative to the total cross section of the hat stringer. The repair stringer may be attached at a plurality of possible attachment points along the cross section of the hat stringer (e.g., as viewed along the spanwise direction of the hat stringer). At each of the plurality of possible attachment points, the repair stringer is shaped to have an inner contour that matches at least a portion of the contour of the interior cavity defined by the hat stringer. The repair stringer may be formed of one or more plies (such as one or more carbon fiber reinforced polymer (CFRP) plies), examples of such repair stringers are provided in the examples of Figures 3A and 3B, 3C, 4A and 4B, 5, and 6A and 6B.

[0098]

[0109] In yet another exemplary embodiment, a hat stringer, or rather a repaired or restored hat stringer, is provided. The hat stringer includes a stringer (e.g., a base stringer or an existing repair stringer). The hat stringer further includes at least one repair stringer connected to the stringer. The repair stringer is connected to the stringer at an attachment point that is one of a plurality of possible attachment points along a cross-section of the hat stringer, and is shaped to have an inner contour that matches at least a portion of the contour of the internal cavity defined by the hat stringer at each of the plurality of possible attachment points. The cross-sectional area of ​​the repair stringer is less than the total cross-sectional area of ​​the hat stringer. Examples of such repaired hat stringers are provided in the examples of Figures 3B, 3C, 4B, 5, and 6B.

[0099]

[0110] In some embodiments, the repaired hat stringer may include at least one Lazy Z repair stringer and at least one Lazy L repair stringer.

[0100]

[0111] FIG. 7 presents a flow diagram of a method 700 for repairing a hat stringer (such as a hat stringer on an aircraft wing).

[0101]

[0112] The method 700 includes, at 702, placing a repair stringer at an attachment location that is one of a plurality of possible attachment locations along a cross-section of the hat-shaped stringer, where at each of the plurality of possible attachment locations, at least a portion of an inner contour of the repair stringer matches at least a portion of a contour of an internal cavity defined by the hat-shaped stringer, and a cross-sectional area of ​​the repair stringer as viewed along a first direction is less than a total cross-sectional area of ​​the hat-shaped stringer as viewed along the first direction. Thus, the repair stringer may be considered to have a partial cross-section relative to the hat-shaped stringer. The repair stringer may be placed relative to a base stringer and / or another stringer (e.g., another repair stringer).

[0102]

[0113] In some implementations of the method, at each of the plurality of possible attachment locations, the repair stringer has a web segment that extends parallel to the stringer's web segment. In other words, at each of the plurality of possible attachment locations, the repair stringer has a web segment that extends parallel to the web portion of the internal cavity's profile. In some further implementations, at each of the plurality of possible attachment locations, the repair stringer has at least one segment that extends parallel to the stringer's cap segment or flange segment. In other words, at each of the plurality of possible attachment locations, the repair stringer has at least one segment that extends parallel to the stringer's cap segment or the stringer's flange segment. In yet another implementation, at each of the plurality of possible attachment locations, the repair stringer has one segment that extends parallel to the stringer's cap segment and one segment that extends parallel to the stringer's flange segment. In other words, at each of a plurality of possible attachment points, the repair stringer has one web segment that extends parallel to the cap portion of the internal cavity profile and one segment that extends parallel to the flange segment of the stringer.

[0103]

[0114] In yet a further implementation, the hat stringer defines a midplane that divides a first side and a second side of the hat stringer. In such implementation, the plurality of possible attachment locations includes a first possible attachment location where the repair stringer is primarily positioned on the first side of the hat stringer and a second possible attachment location where the repair stringer is primarily positioned on the second side of the hat stringer. In this manner, the repair stringer can be attached to either the first or second side of the hat stringer, and at least a portion of the inner contour of the repair stringer matches at least a portion of the contour of the interior cavity defined by the hat stringer, regardless of whether the repair stringer is attached to the first or second possible attachment location.

[0104]

[0115] In a further implementation, the repair stringer has a cap segment, a flange segment, and a web segment that extends between and connects the cap and flange segments. For example, the repair stringer may have a "lazy Z" cross-section. In such implementations, when the repair stringer is placed at its attachment point, the cap segment, web segment, and flange segment of the repair stringer extend parallel to the cap segment, web segment, and flange segment of the stringer, respectively. In other words, when the repair stringer is placed at its attachment point, the cap segment, web segment, and flange segment of the repair stringer extend parallel to the cap portion of the internal cavity profile, the web portion of the internal cavity profile, and the flange segment of the stringer, respectively.

[0105]

[0116] In some additional implementations, the plurality of possible attachment points includes at least four possible attachment points, in which the hat stringer defines a midplane that divides a first side and a second side of the hat stringer, and the at least four possible attachment points may include at least two possible attachment points where the repair stringer is primarily positioned on the first side of the hat stringer and at least two possible attachment points where the repair stringer is primarily positioned on the second side of the hat stringer.

[0106]

[0117] In some implementations, the at least two possible attachment points where the repair stringer is primarily positioned on a first side of the hat-shaped stringer include a first attachment point and a second attachment point, where at the first attachment point, one segment of the repair stringer extends parallel to a first flange segment of the stringer and another segment of the repair stringer extends parallel to a first web segment of the stringer, and where at the second attachment point, one segment of the repair stringer extends parallel to a cap segment of the stringer and another segment of the repair stringer extends parallel to the first web segment of the stringer. Further, in such implementations, the at least two possible attachment points where the repair stringer is primarily positioned on the second side of the hat-shaped stringer include a first attachment point and a second attachment point, where at the first attachment point on the second side, one segment of the repair stringer extends parallel to the cap segment of the stringer and another segment of the repair stringer extends parallel to the second web segment of the stringer, and at the second attachment point on the second side, one segment of the repair stringer extends parallel to the second flange segment of the stringer and another segment of the repair stringer extends parallel to the second web segment of the stringer.

[0107]

[0118] In some further implementations where the plurality of possible attachment points includes at least four possible attachment points, the stringer includes a first flange segment, a first web segment, a cap segment, a second web segment, and a second flange segment, and the plurality of possible attachment points along a cross section of the hat stringer includes a first attachment point, a second attachment point, a third attachment point, and a fourth attachment point. At the first attachment point, one segment of the repair stringer extends parallel to the first flange segment of the stringer and another segment of the repair stringer extends parallel to the first web segment of the stringer. At the second attachment point, one segment of the repair stringer extends parallel to the cap segment of the stringer and another segment of the repair stringer extends parallel to the first web segment of the stringer. At the third attachment location, one segment of the repair stringer extends parallel to the stringer cap segment and another segment of the repair stringer extends parallel to the stringer second web segment, and at the fourth attachment location, one segment of the repair stringer extends parallel to the stringer second flange segment and another segment of the repair stringer extends parallel to the stringer second web segment. In such an implementation, the repair stringer may be a first repair stringer, the attachment point may be a first attachment point, and the method may further include placing a second repair stringer at the second attachment point, placing a third repair stringer at the third attachment point, and placing a fourth repair stringer at the fourth attachment point, and connecting the second repair stringer, the third repair stringer, and the fourth repair stringer to the stringer at the second attachment point, the third attachment point, and the fourth attachment point, respectively, and the first repair stringer is connected to the stringer at the first attachment point.

[0108]

[0119] In some further implementations, the first and second repair stringers physically overlap one another, the second and third repair stringers physically overlap one another, and the third and fourth repair stringers physically overlap one another (e.g., see examples in Figures 4A and 4B). In yet other implementations, the first, second, third, and fourth repair stringers all have the same cross-section, and the second repair stringer is oriented vertically and horizontally flipped relative to the first repair stringer, the third repair stringer is oriented vertically flipped relative to the first repair stringer, and the fourth repair stringer is oriented horizontally flipped relative to the first repair stringer (e.g., see examples in Figures 4A and 4B).

[0109]

[0120] In some implementations of method 700, the repair stringer may have a "lazy Z" cross-sectional shape and may be attachable to multiple possible attachment points along the cross-section of the hat stringer. Also, at least a portion of the inner contour of the repair stringer matches at least a portion of the contour of the internal cavity defined by the hat stringer, regardless of its attachment point. For example, the repair stringer may be attached to the attachment point where the first repair stringer 300 is attached in FIGS. 3A and 3B, the attachment point where the second repair stringer 310 is attached in FIGS. 3A and 3B, or somewhere else. At each of these attachment points, the inner contour of the repair stringer matches at least a portion of the contour of the internal cavity of the hat stringer. In some implementations, the repair stringer is attachable to at least two possible attachment points. In some implementations, a repair stringer having a "lazy Z" cross-sectional shape can be attached to multiple possible attachment locations along the cross-section of the hat stringer, and with different attachment orientations at at least two of the possible attachment locations (e.g., a first orientation in which the repair stringer is upside-down at a first attachment location, and a second orientation in which the repair stringer is flipped horizontally relative to the first orientation at a second attachment location), such that at least a portion of the interior contour of the repair stringer matches at least a portion of the contour of the interior cavity defined by the hat stringer at each attachment orientation.

[0110]

[0121] In some alternative implementations of method 700, the repair stringer may have a "lazy Z" cross-sectional shape and may be attachable to multiple possible attachment points along the cross-section of the hat stringer, and at least a portion of the interior contour of the repair stringer matches at least a portion of the contour of the interior cavity defined by the hat stringer regardless of its attachment point. For example, the repair stringer may be attached to the attachment point where the first repair stringer 400 is attached in Figures 4A and 4B, where the second repair stringer 410 is attached in Figures 4A and 4B, where the third repair stringer 420 is attached in Figures 4A and 4B, where the fourth repair stringer 430 is attached in Figures 4A and 4B, or somewhere else. At each of these attachment points, the interior contour of the repair stringer matches at least a portion of the contour of the interior cavity of the hat stringer. In some implementations, the repair stringer is attachable to at least four possible attachment points.

[0111]

[0122] In some further implementations, a repair stringer having a "lazy L" cross-sectional shape can be attached to a plurality of possible attachment locations along the cross-section of the hat stringer, and in different attachment orientations at at least four of the possible attachment locations (e.g., a first attachment location in a first orientation where the repair stringer is in one up-down orientation, a second attachment location in a second orientation where the repair stringer is up-down relative to the first orientation, a third attachment location in a third orientation where the repair stringer is in the same up-down orientation but flipped horizontally relative to the first orientation, and a fourth attachment location in a fourth orientation where the repair stringer is up-down and flipped horizontally relative to the first orientation). In each attachment orientation, at least a portion of the interior contour of the repair stringer matches at least a portion of the contour of the interior cavity defined by the hat stringer.

[0112]

[0123] Method 700 includes connecting the repair stringer to a stringer of the hat stringer at an attachment point, at 704. For example, the repair stringer may be connected to the hat stringer in any suitable manner (e.g., by mechanical fasteners, a heat treatment process, a compression process, combinations thereof, etc.).

[0113]

[0124] In some further implementations, the repair stringer may be a first repair stringer, and the method 700 may further include placing a second repair stringer at an attachment location along a cross-section of the hat stringer, the second repair stringer being shaped to have an inner contour that matches at least a portion of a contour of the internal cavity. Like the first repair stringer, the cross-sectional area of ​​the second repair stringer when viewed along the first direction is less than the total cross-sectional area of ​​the hat stringer when viewed along the first direction. Thus, the second repair stringer may be considered to have a partial cross-section relative to the hat stringer. In some implementations, the second repair stringer has the same cross-sectional shape as the first repair stringer, for example when viewed along the first direction.

[0114]

[0125] In some further implementations, the second repair stringer is positioned such that its cap segment physically overlaps and each extends parallel to the cap segment of the stringer, or in other words, each extends parallel to the cap portion of the contour of the hat stringer's interior cavity. In still further implementations, the first repair stringer has a web segment that physically overlaps with the first web segment of the stringer, and the second repair stringer has a web segment that physically overlaps with the second web segment of the stringer.

[0115]

[0126] In yet additional implementations, the second repair stringer has a flange segment that extends parallel to but is spaced apart from the second flange segment of the stringer, In such implementations, the method 700 may further include disposing one or more shims between the second flange segment and the second repair stringer flange segment.

[0116]

[0127] In implementations in which a second repair stringer is positioned along a cross section of the hat-shaped stringer, method 700 may further include, at 704, coupling the second repair stringer to the stringer, for example by mechanical fasteners, a heat treatment process, a compression process, combinations thereof, etc.

[0117]

[0128] FIG. 8 presents a flow diagram of a method 800 for repairing a hat stringer (such as a hat stringer on an aircraft wing).

[0118]

[0129] The method 800 includes, at 802, positioning a first repair stringer along a cross section of the hat stringer, where an inner contour of the first repair stringer matches at least a portion of a contour of the internal cavity defined by the hat stringer. As an example, the first repair stringer may have a "lazy Z" cross-sectional shape. As another example, the first repair stringer may have a "lazy L" cross-sectional shape. The first repair stringer may be positioned such that at least a first segment of the first repair stringer is disposed parallel to a web portion of the contour of the internal cavity, and such that a second segment of the first repair stringer is disposed parallel to a cap portion of the contour of the internal cavity, or such that the second segment is disposed parallel to a flange segment of the base stringer. In some implementations, the first repair stringer can include a third segment connected to the second segment through the first segment, the third segment extending parallel to the second segment.

[0119]

[0130] The method 800 includes, at 804, positioning a second repair stringer along a cross section of the hat stringer, where an inner contour of the second repair stringer matches at least a portion of the contour of the internal cavity, and the first and second repair stringers are positioned such that a segment of the second repair stringer physically overlaps a segment of the first repair stringer. As one example, the second repair stringer may have a "lazy Z" cross-sectional shape. As another example, the second repair stringer may have a "lazy L" cross-sectional shape. The second repair stringer may be positioned such that at least a first segment of the second repair stringer is positioned parallel to a web portion of the contour of the internal cavity. The web portion of the profile of the internal cavity may be the same web portion as the first segment of the first repair stringer is aligned parallel to, or a different web portion. The second segment of the second repair stringer may be positioned parallel to the cap portion of the profile of the internal cavity or such that the second segment of the second repair stringer is positioned parallel to the flange segment of the base stringer. In some implementations, the second repair stringer may include a third segment connected to the second segment of the second repair stringer through the first segment of the second repair stringer. The third segment of the second repair stringer extends parallel to the second segment of the second repair stringer.

[0120]

[0131] Further, in some implementations, the first and second repair stringers are positioned such that a segment of the second repair stringer physically overlaps a segment of the first repair stringer along the web section of the hat stringer (an example is shown in FIG. 4A , where web segment 414 of second repair stringer 410 physically overlaps web segment 404 of first repair stringer 400 along the web section of hat stringer 200). In yet another implementation, the first and second repair stringers are positioned such that a segment of the second repair stringer physically overlaps a segment of the first repair stringer along the cap section of the hat stringer (an example is shown in FIG. 3B , where cap segment 316 of second repair stringer 310 physically overlaps cap segment 306 of first repair stringer 300 along the cap section of the hat stringer 200).

[0121]

[0132] Method 800 includes connecting the first repair stringer and the second repair stringer to a stringer of the hat stringer, at 806. For example, the repair stringers may be connected to the hat stringer in any suitable manner, such as by mechanical fasteners (such as in the examples of FIGS. 3B, 3C, 4B), a heat treatment process, a compression process, combinations thereof, etc.

[0122]

[0133] FIG. 9 presents a flow diagram of a method 900 for performing a splice repair on a hat stringer (such as an aircraft wing hat stringer).

[0123]

[0134] The method 900 includes, at 902, positioning a first repair stringer such that a segment of the first repair stringer is positioned in or adjacent to the plane in which the missing section of the base stringer was previously located. By way of example, in FIG. 6A, the first repair stringer 610 is shown positioned such that the web segment 614 of the first repair stringer 610 is positioned in or adjacent to the plane 208 in which the missing section 206 of the base stringer 210 was previously located. FIG. 6B provides another example. In some implementations, the missing section may include one or more web segments, cap segments, or a combination thereof of the base stringer.

[0124]

[0135] Method 900 further includes positioning the second and third repair stringers at 904 such that the second and third repair stringer segments sandwich a first repair stringer segment positioned in or adjacent to the plane. By way of example, in Figure 6A, second repair stringer 620 and third repair stringer 630 are shown positioned such that their respective web segments 624, 634 sandwich a web segment 614 of first repair stringer 610 positioned in or adjacent to plane 208. Figure 6B provides another example.

[0125]

[0136] The method 900 also includes positioning the fourth repair stringer such that a segment of the fourth repair stringer and the first repair stringer sandwich the second repair stringer, at 906. By way of example, in Figure 6A, the fourth repair stringer 640 is shown positioned such that a web segment 644 of the fourth repair stringer 640 and a web segment 614 of the first repair stringer 610 sandwich a web segment 624 of the second repair stringer 620. Figure 6B provides another example.

[0126]

[0137] The method 900 also includes, at 908, coupling the first, second, third, and fourth repair stringers to the base stringer. For example, the repair stringers may be coupled to the base stringer in any suitable manner, such as by mechanical fasteners (such as in the examples of FIG. 6A or FIG. 6B), a heat treatment process, a compression process, combinations thereof, etc.

[0127]

[0138] In some implementations, the first, second, third, and fourth repair stringers are all shaped to have an inner contour that matches at least a portion of a contour of the interior cavity defined by the hat stringer, hi some further implementations, the first, second, third, and fourth repair stringers all have the same cross-section as one another.

[0128]

[0139] In some further implementations, the second and third repair stringers have the same mounting orientation, and the first and fourth repair stringers have the same mounting orientation. For example, in the example of Figure 6A, the second and third repair stringers 620, 630 have the same mounting orientation, and the first and fourth repair stringers 610, 640 have the same mounting orientation. Specifically, in the example of Figure 6A, the second and third repair stringers 620, 630 are oriented in a vertically and horizontally inverted manner relative to the first and fourth repair stringers 610, 640.

[0129]

[0140] In some implementations, the missing section includes a first web segment, a cap segment, and a second web segment of the base stringer. In such implementations, the first, second, third, and fourth repair stringers form a first set of repair stringers that are coupled to the base stringer to repair the first web segment of the base stringer and a first portion of the cap segment. In such implementations, the method 900 may further include positioning a second set of repair stringers, which may include the first, second, third, and fourth repair stringers, and coupling the second set of repair stringers to the base stringer to repair the second web segment of the base stringer and a second portion of the cap segment. An example of the first set of repair stringers and the second set of repair stringers utilized to splice a damaged base stringer is illustrated in FIG. 6A.

Claims

1. 1. A method comprising: placing (702) a repair stringer (300, 400) at an attachment location that is one of a plurality of possible attachment locations along a cross-section of the hat-shaped stringer (200), wherein at each of the plurality of possible attachment locations, at least a portion of an inner contour (308) of the repair stringer (300) matches at least a portion of a contour (224) of an internal cavity (222) defined by the hat-shaped stringer (200); Positioning (702) a repair stringer (300, 400) such that a cross-sectional area of ​​the repair stringer (300) when viewed along a first direction (D1) is smaller than a combined cross-sectional area of ​​the hat stringers (200) when viewed along the first direction (D1); connecting (704) the repair stringer (300) to a stringer (210) of the hat stringer (200) at the attachment point; The method (700).

2. 2. The method (700) of claim 1, wherein at each of the plurality of possible attachment locations, the repair stringer (300) has a web segment (304) that extends parallel to a web portion (224A) of the contour (224) of the internal cavity (222).

3. 3. The method (700) of claim 2, wherein at each of the plurality of possible attachment points, the repair stringer (300) has at least one segment (306, 302) that extends parallel to a cap portion (224B) of the internal cavity (222) or a flange segment (212) of the stringer (210).

4. 2. The method of claim 1, wherein the hat-shaped stringer defines a midplane that divides a first side and a second side of the hat-shaped stringer, and wherein the plurality of possible attachment locations includes a first possible attachment location where the repair stringer is primarily positioned on the first side of the hat-shaped stringer and a second possible attachment location where the repair stringer is primarily positioned on the second side of the hat-shaped stringer.

5. 2. The method of claim 1, wherein the repair stringer (300) comprises a cap segment (306), a flange segment (302), and a web segment (304) extending between and connecting the cap segment (306) and the flange segment (302), and wherein when the repair stringer (300) is placed at the attachment site, the cap segment (306), the web segment (304), and the flange segment (302) of the repair stringer (300) extend parallel to the cap segment (216), web segment (214), and flange segment (212) of the stringer (210), respectively.

6. the repair stringer (300) is a first repair stringer (300), and the method (700) further comprises:

2. The method of claim 1, comprising: positioning a second repair stringer (310) at an attachment location along the cross section of the hat-shaped stringer (200), the second repair stringer (310) being shaped to have an inner contour (318) that matches at least a portion of the contour of the internal cavity (222), a cap segment (316) of the second repair stringer (310) and a cap segment (306) of the first repair stringer (300) physically overlap one another and each extend parallel to a cap portion (224B) of the contour (224) of the internal cavity (222).

7. 7. The method (700) of claim 6, wherein the first repair stringer (300) has a web segment (304) that physically overlaps with a first web segment (214) of the stringer (210), and the second repair stringer (310) has a web segment (314) that physically overlaps with a second web segment (218) of the stringer (210).

8. the second repair stringer (310) having a flange segment (312) extending parallel to but spaced from the second flange segment (220) of the stringer (210), the method (700) further comprising:

8. The method (700) of claim 7, comprising disposing one or more shims (320) between the second flange segment (220) and the flange segment (312) of the second repair stringer (310).

9. 9. The method (700) of claim 8, wherein the second repair stringer (310) has the same cross-sectional shape as the first repair stringer (300) when viewed along the first direction (D1).

10. The method (700), placing a second repair stringer (420) at an attachment location along the cross-section of the hat stringer (200), the second repair stringer (420) being shaped to have an inner contour (418) that matches at least a portion of the contour (224) of the internal cavity (222); placing a third repair stringer (450) at an attachment location along the cross-section of the hat stringer (200), the third repair stringer (450) having a first web segment (454), a cap segment (456), and a second web segment (458); Further comprising:

2. The method (700) of claim 1, wherein the first web segment (454) is connected to the repair stringer (400), the cap segment (456) is connected to the stringer (210), and the second web segment (458) is connected to the second repair stringer (420).

11. 2. The method of claim 1, wherein the hat-shaped stringer defines a midplane that divides a first side and a second side of the hat-shaped stringer, and wherein the plurality of possible attachment points includes at least four possible attachment points, the at least four possible attachment points including at least two possible attachment points where the repair stringer may be primarily positioned on the first side of the hat-shaped stringer and at least two possible attachment points where the repair stringer may be primarily positioned on the second side of the hat-shaped stringer.

12. the at least two possible attachment points at which the repair stringer may be positioned primarily on the first side (232) of the hat stringer (200) include a first attachment point and a second attachment point; At the first attachment location, one segment of the repair stringer (300) extends parallel to a first flange segment (212) of the stringer (210) and another segment (304) of the repair stringer (300) extends parallel to a first web segment (214) of the stringer (210); 12. The method (700) of claim 11, wherein at the second attachment location, one segment of the repair stringer (300) extends parallel to a cap segment (216) of the stringer (210) and another segment (304) of the repair stringer (300) extends parallel to the first web segment (214) of the stringer (210).

13. the at least two possible attachment points at which the repair stringer is primarily positioned on the second side (234) of the hat-shaped stringer (200) include a first attachment point and a second attachment point; At the first attachment point, one segment of the repair stringer (300) extends parallel to a cap segment (216) of the stringer (210) and another segment (314) of the repair stringer (300) extends parallel to a second web segment (218) of the stringer (210); 13. The method (700) of claim 12, wherein at the second attachment location, one segment (312) of the repair stringer (300) extends parallel to a second flange segment (220) of the stringer (210) and another segment (314) of the repair stringer (300) extends parallel to the second web segment (218) of the stringer (210).

14. the stringer (210) includes a first flange segment (212), a first web segment (214), a cap segment (216), a second web segment (218), and a second flange segment (220), and the plurality of possible attachment points along the cross-section of the hat stringer (200) includes a first attachment point, a second attachment point, a third attachment point, and a fourth attachment point; At the first attachment location, one segment (402) of the repair stringer (400) extends parallel to the first flange segment (212) of the stringer (210) and another segment (404) of the repair stringer (400) extends parallel to a first web segment (214) of the stringer (210); At the second attachment point, one segment (402) of the repair stringer (400) extends parallel to the cap segment (216) of the stringer (210) and another segment (404) of the repair stringer (300) extends parallel to the first web segment (214) of the stringer (210); At the third attachment point, one segment (402) of the repair stringer (400) extends parallel to the cap segment (216) of the stringer (210) and another segment (402) of the repair stringer (400) extends parallel to the second web segment (218) of the stringer (210); 2. The method (700) of claim 1, wherein at the fourth attachment location, one segment (402) of the repair stringer (400) extends parallel to the second flange segment (220) of the stringer (210) and another segment of the repair stringer (400) extends parallel to the second web segment (218) of the stringer (210).

15. the repair stringer (400) is a first repair stringer and the attachment point is a first attachment point, the method (700) further comprising: placing a second repair stringer (410) at the second attachment location; placing a third repair stringer (420) at the third attachment location; placing a fourth repair stringer (430) at the fourth attachment location; and connecting the second repair stringer (410), the third repair stringer (420), and the fourth repair stringer (430) to the stringer (210) at the second attachment point, the third attachment point, and the fourth attachment point, respectively, wherein the first repair stringer (410) is connected to the stringer (210) at the first attachment point.

16. 16. The method (700) of claim 15, wherein the first repair stringer (400) and the second repair stringer (410) physically overlap one another, the second repair stringer (410) and the third repair stringer (420) physically overlap one another, and the third repair stringer (420) and the fourth repair stringer (430) physically overlap one another.

17. 17. The method (700) of claim 16, wherein the first repair stringer (400), the second repair stringer (410), the third repair stringer (420), and the fourth repair stringer (430) all have the same cross-sectional shape when viewed along the first direction (D1), and the second repair stringer (410) is oriented vertically and horizontally flipped relative to the first repair stringer (400), the third repair stringer (420) is oriented vertically flipped relative to the first repair stringer (400), and the fourth repair stringer (430) is oriented horizontally flipped relative to the first repair stringer (400).

18. and wherein the repair stringer (300) is a first repair stringer (610) positioned such that a segment (614) of the first repair stringer (610) is positioned in or adjacent to a plane in which a missing section (206) of the stringer (210) was previously located, the method (700) further comprising: positioning a second repair stringer (620) and a third repair stringer (630) such that a segment (624) of the second repair stringer (620) and a segment (634) of the third repair stringer (630) sandwich the segment (614) of the first repair stringer (610) positioned in or adjacent to the plane; positioning a fourth repair stringer (640) such that a segment (644) of the fourth repair stringer (640) and the first repair stringer (610) sandwich the second repair stringer (310); 2. The method (700) of claim 1, comprising connecting the first repair stringer (610), the second repair stringer (620), the third repair stringer (630), and the fourth repair stringer (640) to each other and to the stringer (210).

19. 1. A method (800), comprising: positioning a first repair stringer (300) along a cross section of the hat-shaped stringer (200), wherein an inner contour (308) of the first repair stringer (300) matches at least a portion of a contour (224) of an internal cavity (222) defined by the hat-shaped stringer (200); placing a second repair stringer (310) along the cross section of the hat stringer (200), wherein an inner contour (318) of the second repair stringer (310) matches at least a portion of the contour (224) of the internal cavity (222); the first repair stringer (300) and the second repair stringer (310) are positioned such that a segment (316) of the second repair stringer (310) physically overlaps a segment (306) of the first repair stringer (300), and the method (800) further comprises: A method (800) comprising connecting the first repair stringer (300) and the second repair stringer (310) to a stringer (210) of the hat stringer (200).

20. A repair stringer (300, 400), a web segment (304) having an inner contour (308) shaped to match a web portion (224A) of a contour (224) of an interior cavity (222) defined by the hat stringer (200); at least one of a cap segment (306) and a flange segment (302) extending from the web segment (304); the repair stringer (300) has a partial cross section relative to the total cross section of the hat stringer (200); Repair stringer (300, 400).

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