FR3129381A1 - IMPROVED REPAIR METHOD AND ASSEMBLY FOR AN AIRCRAFT EXTERIOR COATING. - Google Patents

Abstract

The invention relates to a method of repairing a damaged part (10) of an aircraft having a damaged zone, the method comprising: making an opening (12) in the entire thickness of the damaged part (10) around a damaged area; positioning a doubler (14) on the inner surface (10i) of the damaged part (10), the doubler (14) comprising a support surface (14a) of a shape complementary to the shape of said inner surface (10i), and the doubler (14) having a relief (14b) having an outer surface (14d) and a shape complementary to the shape of said opening (12), such that said relief (14b) fills said opening (12) when said surface d seat (14a) is positioned against said interior surface (10i); fix the doubler (14) on the damaged part (10). It is thus possible to recreate an aerodynamic profile in accordance with the aerodynamic requirements of the aircraft, carrying out a simplified and faster repair. Fig. 5

Description

IMPROVED REPAIR METHOD AND ASSEMBLY FOR AN AIRCRAFT EXTERIOR COATING.

The present invention relates to a method for repairing an exterior coating of an aircraft. The invention relates more particularly to a method for repairing, a repair element and an assembly for repairing an exterior covering of an aircraft, the repair assembly comprising the repair element.

PRIOR ART

The exterior coatings of aircraft are sometimes subject to damage, in particular due to impacts with birds, but also impacts with tools, airport vehicles or even airport facilities. The impacts created by shocks cause areas of damage likely to present modifications in terms of mechanical resistance, areas in which structural defects may appear. In addition, certain areas of the fuselage of an aircraft are particularly critical and, in addition to the changes in resistance likely to occur following an impact, changes in shape can lead to aerodynamic changes such as is the case around an air inlet of an engine, on a wing leading edge, on an underside, a tail unit, or even on other external surfaces of the aircraft.

The presence of a zone of damage on such a surface requires a maintenance intervention which can be long and complex.

The situation can be improved.

An object of the present invention is to provide a method for repairing part of the exterior skin of an aircraft, making it possible to reduce the repair time and/or the downtime of the aircraft.

To this end, a method is proposed for repairing a damaged part of an aircraft comprising an inner surface and an outer surface, the outer surface, at least, having a damaged zone, the method comprising the steps:

- operate an opening in the entire thickness of the damaged part around a damaged zone, so as to remove the damaged zone from the damaged part of the aircraft,

- positioning an inner doubler on the inner surface of the damaged part, the inner doubler comprising a support surface of a shape complementary to the shape of said inner surface of the damaged part, around said opening, and the inner doubler having a relief of a shape complementary to the shape of said opening, so that the relief fills the opening when the bearing surface of the inner doubler is positioned against the inner surface of the damaged part,

- attach the inner doubler to the damaged part of the aircraft.

Advantageously, it is thus possible to recreate an aerodynamic profile in accordance with the aerodynamic requirements of the aircraft, by carrying out a simplified and therefore faster repair.

The repair process according to the invention may also include the following characteristics, considered alone or in combination:

• The doubler positioned according to the repair method has a relief configured so that its outer surface has surface continuity with the outer surface of the part of the aircraft into which it is intended to be inserted.

- The repair process includes, prior to the step of making an opening in the damaged part, the steps:

- remove the damaged part,

- obtain information representative of the damaged part, and,

- define, from the information obtained, all or part of the dimensions of the interior doubler.

- The repair process includes, after the stage of defining the dimensions of the interior doubler:

- print, using 3D printing technology, the inner doubler, from the defined dimensions.

- The repair process includes, after the interior doubler printing step:

- print, using said 3D printing technology, and from the defined dimensions, a drilling template configured to facilitate the fixing of the inner doubler to the damaged part.

- The printing of the inner doubler and the printing of the drilling template are carried out during the same 3D printing phase of the repair process.

The invention also relates to an aircraft interior doubler device, comprising a bearing surface of shape substantially complementary to the shape of an interior surface of a damaged part of the aircraft, and having a relief configured to be inserted in an opening made in the damaged part, so that the relief fills the opening when the bearing surface of the doubler is positioned against the surface.

Advantageously, the relief is configured so that its outer surface has surface continuity with the outer surface of the part of the aircraft in which it is intended to be inserted.

According to one embodiment of the invention, the interior aircraft doubler is made of titanium.

The invention also relates to an aircraft repair assembly comprising an interior doubler as mentioned above and a drilling jig configured to facilitate the fixing by rivets of the doubler on the damaged part of the aircraft.

The characteristics of the invention mentioned above, as well as others, will appear more clearly on reading the following description of an exemplary embodiment, said description being made in relation to the attached drawings, among which:

is a schematic representation in perspective of an aircraft engine whose air intake lip has a damaged area;

is a schematic representation, from the front, of a damaged part of the air intake lip including the damaged area visible on the ;

is a schematic representation, from the front, of the damaged part of the aircraft lip already represented on the in which an opening has been made to remove the damaged area;

is a schematic representation, from the front, of an internal repair doubler for the damaged part of the air intake lip shown in the And ;

is a schematic representation of a positioning of the inner repair doubler shown in the on the inner surface of the damaged part of the air intake lip;

is a schematic representation, from the front, of a drilling jig configured to facilitate the attachment of the internal doubler to the internal surface of the damaged part of the air inlet lip; And,

is a diagram representing the steps of a method for repairing a damaged aircraft air intake lip according to one embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

In the present description, the part of the damaged coating that is the subject of the repair process is an air intake lip of an aircraft engine. Obviously, this example is not limiting and the method according to the invention, as well as the doubler and the drilling jig previously described, can be applied to any other part of the exterior skin of the aircraft whose shape allows it, and in particular with regard to parts for which it is advisable to reproduce, during the repair, aerodynamic characteristics identical to those of origin, or at the very least acceptable for the operation in flight of the aircraft.

There schematically represents an aircraft engine 1000 having a longitudinal axis 1001. The engine 1000 is for example of the turbojet type and has an air inlet delimited by an air inlet lip 100 having a predefined aerodynamic profile so as to optimize the flow of air at the engine inlet 1000. According to one embodiment of the invention, the air inlet lip 100, of generally circular shape, is arranged in one or more parts, and, in the illustrated example, in three parts assembled together and positioned between two planes, each perpendicular to the axis 1001. The three assembled parts each form a portion of the air inlet lip 100 generally describing an arc of a circle having a central angle of 120 degrees. One of the parts of the air intake lip 100, part 10 on the , has a damaged area 11. The damaged area 11 is, for example, a sunken area of the outer surface of the damaged part 10, following an impact with an element external to the aircraft (a bird, for example ). In the present description, the terms "external surface" designate the surface in contact with the air present outside the aircraft, which surface is likely to be damaged by contact with any element of the external environment, such as a bird, hail, a land vehicle, another aircraft, for example. The terms “inner surface” designate a surface of a fuselage element located on the opposite side of the element with respect to the outer surface. There schematically illustrates a detailed view of the damaged area 11 of the damaged part 10 of the air intake lip 100. A depressed area following an impact, such as the damaged area 11, is likely to disturb the air flow at the inlet of the engine 1000, which, consequently, can cause disturbances inside the engine 1000. The repair method described in the present description advantageously uses a repair element fixed against a inner surface 10i of the damaged part 10 and having an outer surface condition so as to avoid any unevenness on the outer surface 10e of the air inlet lip 100, after repair, and therefore to present, after repair, a condition surface as aerodynamic as possible and preferably equivalent to the original one. In other words, a single repair element positionable on (against) the inner surface 10i of the air inlet lip is configured to provide surface continuity between the outer surface of the inlet lip d air and the outer surface of the repair element. To do this, the repair process comprises, after removal of the relevant part of the air inlet lip (when the nacelle located around the engine comprises several parts of the air inlet lip), cutting out the part damaged 10 of the air inlet lip aimed at operating an opening whose contour is outside the damaged zone 11, namely that the contour surrounds the damaged zone 11. To do this, a cutting operation is carried out in all the thickness of the damaged part 10 of the air intake lip 100, around the damaged zone 11, so as to remove the damaged zone 11 from the damaged part 10. The illustrates the damaged part 10 having a through opening 12 revealing an edge 12b forming the outline of the opening 12 after removal by cutting of the damaged zone 11, and the illustrates a single repair element 14, as mentioned above, called here "interior doubler" 14 and advantageously configured to be fixed on the interior surface 10i of the damaged part 10 and to provide an exterior surface continuity with the damaged part 10 of the air inlet lip 100. Advantageously, the inner doubler 14 comprises a relief part 14b (also called here “relief” 14b) having an edge 14c forming a limit between a support surface 14a and an outer surface 14d. Cleverly, the doubler 14 is configured so that the relief 14b has a shape complementary to the shape of the opening 12 made in the damaged part 10 of the air inlet lip. Thus, the doubler 14, positioned resting on the inner surface 10i of the damaged part 10 of the air inlet lip, is provided and configured to fit into the opening 12 made by cutting the damaged part 10 and removal of the damaged area 11. The illustrates an operation of positioning the inner doubler 14 on (against) the inner surface 10i of the damaged part 10 of the air inlet lip, and the arrow represented symbolizes the fitting of the relief 14b in the opening 12 of the damaged part 10, so as to ensure surface continuity between the outer surface of the air inlet lip 100 and the outer surface 14d of the doubler 14, after repair.

According to one embodiment, the inner doubler 14 is cleverly produced by 3D printing using ALM technology (from the English acronym “ Additive Layer Manufacturing ” and which means “additive manufacturing layer by layer”), after characterization of the damaged zone then definition of the contour of the opening 12 to operate, and from a modeling of the air inlet lip 100 according to a computer design model (CAD). An ALM technology here designates processes which make it possible to manufacture a physical object "layer by layer", by adding material, and this, from a digital definition of an object (for example according to the French standard NF E 67- 001). Advantageously, the impression of the inner doubler 14 is made of titanium. According to variants, the inner doubler 14 can be made of another material, the characteristics of which are equivalent to those of titanium and satisfy aeronautical use. Advantageously again, the printing of the inner doubler 14 is followed by the printing of a drilling template element 16 defined from the dimensions of the doubler 14 and the original shape of the damaged part 10 of the inlet lip of air, during the same printing phase. The terms "same 3D printing phase" designate here a continuous or quasi-continuous 3D printing operation which allows the printing of the doubler 14 and the drilling jig 16 without dismantling the print head or without having to operate a new adjustment of the 3D printing means used. Cleverly, the drilling jig 16, represented on the , is configured to conform to the outer surface 10e of the damaged part 10, around the opening 12, and has a plurality of openings 16b or recesses 16b, called here "pre-holes" and arranged to operate a guide a drilling tool; the drilling tool being used to operate a multitude of holes both in the damaged part 10 and in the inner doubler 14, respectively aligned two by two, and which then allow fixing by rivets of the inner doubler 14 in the damaged part 10. The drilling template 16 preferably comprises a central opening 16c configured to be positioned opposite the opening 12 of the damaged part 10, before drilling, in order to best position the holes in the bearing surface of the inner doubler 14. The represents only a limited number of pre-holes 16b, for the purpose of increasing clarity, but the pre-holes 16b can of course be more or less numerous to meet mechanical strength constraints.

In other words, after positioning the inner doubler 14 on the inner surface 10i of the damaged part 10, and after placing the drilling jig 16 on the outer surface 10e of this same damaged part 10, the drilling of a plurality of holes, successively guided by the drilling template 16, allows easy insertion of the fixing rivets of the inner doubler 14 on the damaged part 10 of the air inlet lip. A large number of rivets guaranteeing good mechanical strength of the damaged part 10, after repair.

There illustrates a method of repairing the damaged portion 10 of the air intake lip 100 according to one embodiment of the invention. A step S0 is an initial step at the end of which the air inlet lip portion 100 comprising the damaged part 10 of the air inlet lip is placed in a maintenance site and prepared for carrying out a repair. According to a first embodiment of the invention, the method for repairing the damaged part 10 of the air inlet lip comprises a step S1 of removing the portion of the air inlet lip 100 which comprises the damaged portion 10, which includes the damaged area 11. Removal of the lip portion allows access to the inner and outer surfaces of the air inlet lip portion. A precise characterization of the damage present in the damaged part 10 of the air inlet lip is then carried out, during a step S2, so as to obtain information representative of the damaged part. This information is, for example, a length of the damaged zone, a width of the damaged zone, an arc in the center defining a portion of the air inlet lip portion to be cut and removed. This information may equally well be information representative of a part of the part to be replaced as defined (modeled) according to a model of the part in computer-aided design (CAD) software, that is to say forming a file mechanical definition computer of a part, according to 3 dimensions. According to one example, precise measurement of the damaged part of the air inlet lip, implementing laser metrology, allows immediate modeling of a repair element as defined according to a precise format in CAD software. Such tools then make it possible to define, during a step S3, all or part of the dimensions of a repair element of the inner air inlet lip doubler type, so as to be able to print, during a step S4, and using an additive manufacturing method by successive layers of deposited material, the inner doubler 14 configured to repair the damaged part 10 of the air inlet lip. The use of an additive manufacturing technology by layer of material, called "ALM", from a predetermined CAD model, or in other words, from a set of predetermined dimensions characterizing the shapes of the doubler interior 14, makes it possible to produce the interior doubler 14 in titanium, a material well suited for such a repair. The inner doubler 14 thus printed in 3D advantageously comprises in one piece a base having in particular the bearing surface 14a and the relief 14b, defined from data resulting from a prior characterization of the damaged zone 11 and/or of the damaged part 10 as a whole, that is to say from a set of information representative of the damaged part 10 of the air inlet lip 100. Once the inner doubler has been obtained by controlled manufacturing, a cutting step S5 is performed in the damaged part 10 of the air inlet lip, around the damaged zone 11, so as to remove the damaged zone 11 from the damaged part 10. The cut is made so as to operate the opening 12, in the entire thickness of the damaged part 10. A positioning of the inner doubler 14 on the inner surface of the damaged part 10 of the air inlet lip is then carried out during a step S6 , as shown in the . The relief 14b of the inner doubler 14 has a shape complementary to the opening 12 operated in the damaged part 10. In other words, the relief 14b has a shape similar to the cut out part of the damaged part 10 before it has suffered damage. Thus, when the bearing surface 14a of the inner doubler is positioned bearing against the inner surface of the damaged part 10, the relief 14b fits into the opening 12 so as to fill it. In addition, the thickness of the relief 14b is identical to the thickness of the damaged part 10 so that no unevenness exists after the two parts have been fitted together and there is surface continuity after repair between the outer surface of the damaged part 10 and the surface 14d of the relief 14b.

A fixing by rivets of the inner doubler 14 is then carried out, during a step S7, and after drilling a plurality of holes in the two elements which are the inner doubler 14 and the damaged part 10, to house the various rivets therein. of fasteners. The exterior surface condition is then the subject of finishing work (sanding, painting, for example). Advantageously, the CAD tools used allow the definition of a drilling template 16 adapted to the operations of fixing the inner doubler 14 on the damaged part 10, or more exactly on the lip portion comprising the damaged part 10. Printing, by the same 3D printing technology, of the drilling jig 16, configured to present pre-holes, can be carried out during a step S4′ subsequent to the step S4 of 3D printing of the internal doubler 14 and operated in a same and only 3D printing phase. Advantageously, it is then possible to obtain in the same manufacturing operation an inner air inlet lip doubler such as the inner doubler 14 as well as a drilling jig, such as the jig 16, for the purpose of facilitating and speed up repair operations, which can significantly reduce the time to complete a repair. It is thus possible to dispense with the replacement of an entire portion of the air inlet lip, or even the entire air inlet lip, which also has the advantage of significantly reducing the costs of repair.

The invention is not limited solely to the embodiments and examples described above, but relates more generally to any process for repairing a damaged part of an aircraft (for example, but not only, an inlet lip of air) comprising, after removal of the damaged part, the steps: making an opening in the entire thickness of the damaged part around a damaged zone, so as to remove the damaged zone from the damaged part; positioning an inner doubler on the inner surface of the damaged part, the inner doubler comprising a bearing surface of shape substantially complementary to the shape of the inner surface of the damaged part, around the opening made, and the inner doubler having a relief of a shape complementary to the shape of the opening, so that the relief fills the opening when the bearing surface of the inner doubler is positioned against the inner surface of the damaged part; then fixing, preferably by riveting, of the inner doubler to the damaged part of the air inlet lip. Advantageously, an inner doubler and possibly a drilling template as described can be provided quickly, after characterization and/or modeling of the damaged part of an air inlet lip to carry out the optimized repair process.

Claims (10)

A method of repairing a damaged part (10) of an aircraft, said damaged part (10) comprising an inner surface (10i) and an outer surface (10e), the outer surface (10e) at least having a damaged area ( 11), the method comprising the steps:
- operate (S5) an opening (12) in the entire thickness of the damaged part (10) around one of at least said damaged zone (11), so as to remove the damaged zone (11) from the part damaged (10) of the aircraft,
- positioning (S6) an inner doubler (14) on the inner surface (10i) of the damaged part (10), the inner doubler (14) comprising a support surface (14a) of shape substantially complementary to the shape of said inner surface (10i) of the damaged part (10), around said opening (12), and the inner doubler (14) having a relief (14b) of a shape complementary to the shape of said opening (12), so that said relief (14b) fills said opening (12b) when said bearing surface (14a) of the inner doubler (14) is positioned against said inner surface (10i) of the damaged part (10),
- fix (S7) the inner doubler (14) on the damaged part (10) of the aircraft. Method for repairing a damaged part (10) of an aircraft, according to the preceding claim, in which said relief (14b) is configured so that its outer surface (14d) has surface continuity with the outer surface (10e) of the part of the aircraft (10) in which it is intended to be inserted. Method for repairing a damaged part (10) of an aircraft according to one of claims 1 and 2, comprising, prior to the step of making an opening (12) in the damaged part (10), the steps :
- remove (S1) the damaged part (10) of the aircraft,
- obtaining (S2) information representative of the damaged part (10) of the aircraft, and,
- defining (S3), from said information, all or part of the dimensions of the interior doubler (14) and configuring said doubler so that the surface of the doubler has surface continuity with the surface around said opening to be operated. Method for repairing a damaged part (10) of an aircraft according to the preceding claim comprising, after the step (S3) of defining the dimensions of the inner doubler (14):

• printing (S4), using 3D printing technology, said inner doubler (14), from said defined dimensions.

Method for repairing a damaged part (10) of an aircraft according to the preceding claim comprising, after the step of printing (S4) of said interior doubler:

• printing (S4'), by means of said 3D printing technology and from said defined dimensions, a drilling jig (16) configured to facilitate the attachment of said inner doubler to said damaged part (10).

Method for repairing a damaged part (10) of an aircraft according to the preceding claim, in which the impression (S4) of said interior doubler (14) and the impression (S4') of said drilling jig (16) are produced during the same 3D printing phase (S4, S4'). Interior aircraft doubler (14), comprising a support surface (14a) of shape substantially complementary to the shape of an interior surface (10i) of a damaged part (10) of the aircraft and having a relief (14b ) configured to be inserted into an opening (12) made in said damaged part (10), so that said relief (14b) fills said opening (12) when said bearing surface (14a) of the doubler (14) is positioned against said inner surface (10i). Inner doubler (14) according to the preceding claim, in which the said relief (14b) is configured so that its outer surface has surface continuity with the outer surface of the part of the aircraft into which it is intended to be inserted. Interior doubler (14) of an aircraft part according to one of claims 6 and 7, the doubler being made of titanium. Aircraft repair kit comprising an inner doubler (14) according to one of claims 7 to 9, and a drilling jig (16) configured to facilitate the attachment of said doubler (14) to the aircraft.