Method and system for optimizing the maintenance of an aircraft structure against corrosion.

Abstract

- Method and system for optimizing the maintenance of an aircraft structure against corrosion. - The method comprises a step (E1) of collecting corrosion incidents (6) on a plurality of aircraft (AC), a step (E3) of determining the zones (71, 73) and the corrosion incident rates in each of the zones (71, 73), a step (E4) of determining risk zones (19), a step (E5) of determining a corrosion depth (Eb), a step (E6) of determining a corrosion rate, and a step (E7) of determining a proposed inspection frequency for each of the risk zones (19) based on its corrosion rate and a predetermined limit depth (Ec) of each of the risk zones (19). The method makes it possible to obtain a more precise inspection frequency proposal adapted to the different parts of the aircraft structure. Figure for the abstract: Fig. 1

Description

Title of the invention: Method and system for optimizing maintenance of an aircraft structure against corrosion. Technical field

[0001] The present invention relates to a method for optimizing maintenance of an aircraft structure, for example an aircraft fuselage or wings, against corrosion. State of the art

[0002] Currently, during the manufacture of an aircraft, the parts of the aircraft structure, and in particular the parts of the wings or fuselage of said aircraft, undergo different levels of protection against corrosion. This protection depends, among other things, on the location and function of said parts.

[0003] For example, fuselage parts located in the lower portion of the aircraft generally require more corrosion protection than the protection for parts located in the upper portion of the aircraft. Similarly, moving fuselage parts, such as doors or the landing gear bay, generally require more corrosion protection than the protection for fixed fuselage parts.

[0004] There are currently different levels of corrosion protection, namely, in ascending order of increase from least to most: level 1, level 2, level 3 and level 4.

[0005] Corrosion protection is established at the elementary part level and at the assembly level.

[0006] The protection carried out at the elementary part level includes 4 levels:

[0007] Level 1 includes surface treatment, such as tribo-finishing, cadmium plating, anodizing, galvanizing, etc. Level 1 also includes installation without sealant.

[0008] Level 2 includes a surface treatment and a coat of paint. Level 2 also includes an installation with sealant between two parts.

[0009] Level 3 includes a surface treatment and two coats of paint. Level 3 also includes an installation with sealant at the interposition between two parts, as well as a bead of sealant around the entire perimeter.

[0010] Level 4 includes a surface treatment, two coats of paint and a water-repellent treatment. Level 4 also includes an installation with sealant at the interposition between two parts, as well as a bead of sealant covering the edges.

[0011] Furthermore, the fuselage parts are classified into different categories depending on of their need for protection against corrosion: category 1, category 2, category 3, category 4 and category 5.

[0012] Category 1 includes parts and assemblies that require little corrosion protection (level 1 and 2).

[0013] Category 2 includes parts that require level 2 of protection and assemblies that require level 3 of protection.

[0014] Categories 3 and 4 include parts and assemblies that require level 3 protection.

[0015] Category 5 includes parts and assemblies that require level 3 or 4 protection.

[0016] There is currently a two-dimensional map of the aircraft indicating the corrosion zones and the respective protection categories of each of the fuselage parts, as well as the inspection frequencies of the different parts ([Fig.3]).

[0017] However, this mapping is fixed, and is not necessarily optimal. Indeed, the corrosion rate of an aircraft can differ depending on the use made of it and the climate in which it is usually used. The current fixed mapping is therefore not fully satisfactory. Statement of the invention

[0018] The object of the present invention is to overcome the drawbacks mentioned above, and in particular to take into account environmental constraints for the adaptation of maintenance inspection intervals.

[0019] For this, it relates to a method for optimizing maintenance of an aircraft structure against corrosion, the aircraft structure comprising at least one aircraft structure part.

[0020] According to the invention, the method comprises the following steps: - a collection step implemented by a collection unit to collect a plurality of corrosion incidents on a plurality of aircraft, each of the corrosion incidents comprising a position of the corrosion incident, a remaining thickness of the aircraft structural part at the position of the corrosion incident and an age of the aircraft for which the corrosion incident was collected, - a reporting step implemented by a reporting unit to report the plurality of collected corrosion incidents on a digital twin virtually defining an aircraft structure comprising at least one aircraft structure part, - a first determination step implemented by a first determination unit to determine areas and corrosion incident rates in each of the areas for each part of the aircraft structure of the digital twin, the corrosion incident rate of each of the areas being equal to a ratio between number of corrosion incidents collected in each of the areas and a number of aircraft of the plurality of aircraft on which the plurality of corrosion incidents were collected, - a second determination step implemented by a second determination unit to determine risk areas, the risk areas corresponding to areas whose corrosion incident rate is greater than or equal to a predetermined corrosion incident rate, - a third determination step implemented by a third determination unit to determine a corrosion depth for each part of the aircraft structure located in the risk zones from the remaining thickness, - a fourth determination step implemented by a fourth determination unit to determine a corrosion rate for each of the risk zones from the corrosion depth and the age of the aircraft for each part of the aircraft structure comprising a risk zone, - a fifth determination step implemented by a fifth determination unit to determine a proposed inspection frequency for each of the risk areas based on its corrosion rate and a predetermined limit depth of each of the risk areas, - a transmission step implemented by a transmission unit to transmit to a user device the proposed inspection frequency for each of the risk areas.

[0021] Thus, by determining areas on the parts of the aircraft structure for which there are high rates of corrosion incidents, it is possible to determine more precisely and more appropriately the inspection frequencies required before excessive corrosion appears.

[0022] The inspection frequency proposal corresponds to a correction of the inspection frequency initially defined for maintenance. The inspection frequency initially defined for maintenance can therefore be adapted on the basis of the plurality of collected corrosion incidents, when it is determined that the inspection intervals are not optimally defined.

[0023] The aircraft maintenance plan can thus be optimized, making it possible to reduce the inspection frequencies of risk areas, and therefore to limit aircraft downtime and reduce the maintenance tasks to be carried out.

[0024] Advantageously, the first determination step comprises the following sub-steps: - a first cutting sub-step implemented by a first cutting sub-unit to cut each part of the aircraft structure of the digital twin according to a mesh of zones comprising zones of predetermined size, - a first calculation sub-step implemented by a first calculation sub-unit to calculate a corrosion incident rate for each of the zones of the zone mesh.

[0025] In addition, the first determination step further comprises the following sub-steps implemented if at least two zones of the zone mesh of a part of the aircraft structure have a difference in corrosion incident rate greater than a predetermined difference: - a second cutting sub-step implemented by a second cutting sub-unit to cut the part of the aircraft structure according to a sub-mesh of zones comprising zones of predetermined size smaller than the predetermined size of the zones of the mesh of zones, - a second calculation sub-step implemented by a second calculation sub-unit to calculate a corrosion incident rate for each of the zones of the zone sub-mesh.

[0026] Furthermore, the corrosion depth of a part of the aircraft structure determined in the third determination step is equal to a difference between a nominal thickness of the part of the aircraft structure and the remaining thickness of the part of the aircraft structure.

[0027] Furthermore, the corrosion rate of each of the risk zones determined in the fourth determination step is equal to a ratio between the average corrosion depth in each of the risk zones over a time at the end of which this corrosion depth is reached.

[0028] Furthermore, the fifth determination step comprises the following sub-steps: - a third calculation sub-step implemented by a third calculation sub-unit to calculate the inspection frequency required for each of the risk zones so that the corrosion depth reaches the predetermined limit depth, - a determination sub-step implemented by a determination sub-unit to determine the proposed inspection frequency, the proposed inspection frequency being strictly lower than the inspection frequency necessary for each of the risk zones for the corrosion depth to reach the predetermined limit depth.

[0029] The invention also relates to a system for optimizing maintenance of an aircraft structure against corrosion, the aircraft structure comprising at least one part of the aircraft structure.

[0030] According to the invention, the optimization system comprises: - a collection unit for collecting a plurality of corrosion incidents on a plurality of aircraft, each of the corrosion incidents comprising a position of the corrosion incident, a remaining thickness of the aircraft structure part at the position of the corrosion incident and an age of the aircraft for which the corrosion incident was collected, - a reporting unit for reporting the plurality of collected corrosion incidents on a digital twin virtually defining the aircraft structure comprising at least one part of the aircraft structure, - a first determination unit for determining areas and corrosion incident rates in each of the areas for each aircraft structural part of the digital twin, the corrosion incident rate of each of the areas being equal to a ratio between the number of corrosion incidents collected in each of the areas and a number of aircraft of the plurality of aircraft on which the plurality of corrosion incidents were collected, - a second determination unit for determining risk areas, the risk areas corresponding to areas whose corrosion incident rate is greater than or equal to a predetermined corrosion incident rate, - a third determination unit to determine a corrosion depth for each part of the aircraft structure located in each of the risk zones from the remaining thickness, - a fourth determination unit to determine a corrosion rate for each of the risk areas based on the corrosion depth and the age of the aircraft for each part of the aircraft structure comprising a risk area, - a fifth determination unit to determine a proposed inspection frequency for each of the risk areas based on its corrosion rate and a predetermined limit depth for each of the risk areas, - a transmission unit for transmitting to a user device the proposed inspection frequency for each of the risk areas.

[0031] Advantageously, the first determination unit comprises: - a first cutting sub-unit for cutting each part of the aircraft structure of the digital twin according to a mesh of zones comprising zones of predetermined size, - a first calculation sub-unit to calculate a corrosion incident rate for each of the zones in the zone mesh.

[0032] In addition, the first determination unit further comprises: - a second cutting sub-unit for cutting the part of the aircraft structure according to a sub-mesh of zones comprising zones of predetermined size smaller than the predetermined size of the zones of the zone mesh, - a second calculation sub-unit to calculate a corrosion incident rate for each of the zones in the zone sub-mesh.

[0033] Furthermore, the fifth determination unit comprises: - a third calculation sub-unit to calculate the inspection frequency required for each of the risk areas so that the corrosion depth reaches the predetermined limit depth, - a determination sub-unit for determining the proposed inspection frequency, the proposed inspection frequency being strictly lower than the inspection frequency required for each of the risk areas for the corrosion depth to reach the predetermined limit depth. Brief description of the figures

[0034] The attached figures will make it clear how the invention can be implemented. In these figures, identical references designate similar elements.

[0035] [Fig.l] schematically represents the optimization process.

[0036] [Fig.2] schematically represents a cross-section of a fuselage part having a nominal thickness.

[0037] [Fig. 3] represents a fixed two-dimensional map of an aircraft showing fuselage parts to which protection categories have been assigned.

[0038] [Fig.4] represents a portion of an aircraft digital twin on which collected corrosion incidents were reported.

[0039] [Fig.5] represents two curves of evolution of the depth of corrosion of a fuselage part as a function of time.

[0040] [Fig.6] schematically represents the optimization system.

[0041] [Fig.7] represents a side view of one of the plurality of aircraft on which the corrosion incidents are collected. Detailed description

[0042] The optimization process is shown schematically in [Fig.l].

[0043] The optimization method is intended to optimize maintenance of an aircraft structure, or of an aircraft part, including the wings and the aircraft structure against corrosion. The aircraft structure is defined here as being the mechanical structure of an aircraft AC, also called “cell” of the aircraft AC (or “airframe” in English). In the remainder of the description, the method will be described for a fuselage 1, but it is of course applicable to the other elements of the aircraft structure, such as the wings. The fuselage 1 comprises at least one fuselage part 4.

[0044] The optimization method comprises the following steps: - a collection step El implemented by a COL 10 collection unit (COL for “collecting unit” in English), - a reporting step E2 implemented by a reporting unit REP 12 (REP for "reporting unit" in English), - a first determination step E3 implemented by a first determination unit DET1 13 (DET for “determining unit” in English), - a second determination step E4 implemented by a second determination unit DET2 14, - a third determination step E5 implemented by a third determination unit DET3 15, - a fourth determination step E6 implemented by a fourth determination unit DET4 16, - a fifth determination step E7 implemented by a fifth determination unit DET5 17, - a transmission step E8 implemented by a transmission unit TRANS 18 (TRANS for “transmitting unit” in English).

[0045] The collection step E1 is intended to be implemented to collect a plurality of corrosion incidents 6 on a plurality of aircraft AC such as that shown in [Fig. 7]. Each of the corrosion incidents 6 comprises parameters including a position of the corrosion incident 6, a remaining thickness Ea of the fuselage part 4 at the position of the corrosion incident 6 and an age of the aircraft AC for which the corrosion incident 6 was collected. For example, in this collection step E1, the plurality of corrosion incidents are collected and stored in a database DB 11 (DB for “database” in English). The collection unit 10 may correspond to an input device, such as a keyboard. The database 11 may thus group together the returns to service of the plurality of aircraft AC.

[0046] A "corrosion incident" is a region or zone of the fuselage 1 that includes corrosion. The corrosion incident includes at least the position on the fuselage 1 of the region that includes the corrosion. The position may correspond to a position of a corroded surface.

[0047] The reporting step E2 is intended to be implemented to report the plurality of corrosion incidents 6 collected on a digital twin 2 simulating a fuselage 1 comprising at least one fuselage part 4. Thus, each of the corrosion incidents 6 is reported on the digital twin 2 at their respective position ([Fig.4]). [Fig.4] represents a fuselage part 4 of the digital twin 2 or a part of the fuselage 1 of the digital twin 2.

[0048] The digital twin 2 corresponds to a modeling of an aircraft AC in three dimensions. This modeling can be implemented by a processor of a calculator, such as a computer.

[0049] The first determination step E3 is intended to be implemented to determine zones 71, 73 and corrosion incident rates in each of said zones. areas 71,73 for each part 4 of the fuselage of the digital twin 2. The corrosion incident rate of each of the areas 71,73 is equal to a ratio between a number of corrosion incidents 6 collected in each of the areas 71,73 of the plurality of aircraft AC and a number of aircraft AC equal to the number of aircraft of the plurality of aircraft AC.

[0050] The first determination step E3 may comprise the following sub-steps: - a first cutting sub-step E31 implemented by a first cutting sub-unit CUTI 131 (CUT for “cutting unit” in English), - a first calculation sub-step E32 implemented by a first calculation sub-unit COMP1 132 (COMP for “computing unit” in English). The first cutting sub-step E31 is intended to be implemented to cut each fuselage part 4 of the digital twin 2 according to a mesh of zones 70 comprising zones 71 of predetermined size.

[0051] The mesh of zones 70 may correspond to a mesh having square-shaped cells or any other shape adapted to the part 4. These cells correspond to the zones 71.

[0052] [Fig. 4] represents a mesh of zones 70 in solid lines. This mesh of zones 70 defines the zones 71. The predetermined size of the zones 71 depends on the precision that is desired to determine the corrosion incident rates determined for each of the zones 71. The zones 71 of the mesh of zones 70 may have a size smaller than the size of a fuselage part 4.

[0053] The first calculation sub-step E32 is intended to be implemented to calculate a corrosion incident rate for each of the zones 71 of the zone mesh 70.

[0054] Furthermore, the first determination step E3 may further comprise the following sub-steps: - a second cutting sub-step E33 implemented by a second cutting sub-unit CUT2 133, - a second calculation sub-step E34 implemented by a second calculation sub-unit COMP2 134.

[0055] Sub-steps E33 and E34 are implemented if at least two zones 71 of the mesh of zones 70 of a fuselage part 4 have a difference in corrosion incident rate greater than a predetermined difference.

[0056] The second sub-step E33 is intended to be implemented to cut the fuselage part 4 according to a sub-mesh of zones 72 comprising zones 73 of predetermined size smaller than the predetermined size of the zones 71 of the mesh of zones 70.

[0057] For example, a zone 71 of the zone mesh 70 is cut by a sub-mesh of zones 72 comprising zones 73. As for the zone mesh 70, the sub- zone mesh 72 may correspond to a mesh having square-shaped cells or any other shape suitable for part 4 or the cells of zone mesh 70. These cells of zone sub-mesh 72 correspond to zones 73.

[0058] For example, [Fig.4] shows in dotted lines, a sub-mesh of zones 72 comprising zones 73 having a size smaller than the size of zones 71.

[0059] The second calculation sub-step E34 is intended to be implemented to calculate a corrosion incident rate for each of the zones 73 of the zone sub-mesh 72.

[0060] The second determination step E4 is intended to be implemented to determine risk zones 19. The risk zones 19 correspond to the zones 71, 73 whose corrosion incident rate is greater than or equal to a predetermined corrosion incident rate ([Fig.4]).

[0061] The third determination step E5 is intended to be implemented to determine a corrosion depth Eb for each fuselage part 4 located in the risk zones 19 from the remaining thickness Ea ([Fig.2]).

[0062] The corrosion depth Eb of a fuselage part 4 may be equal to a difference between a nominal thickness E of the fuselage part 4 and the remaining thickness Ea of the fuselage part 4.

[0063] The fourth determination step E6 is intended to be implemented to determine a corrosion rate for each of the risk zones 19 from the corrosion depth Eb and the age of the aircraft for each fuselage part 4 comprising a risk zone 19.

[0064] The corrosion rate of each of the risk zones 19 may be equal to a ratio between the average corrosion depth Eb in each of the risk zones 19 over a time at the end of which this corrosion depth Eb is reached.

[0065] According to an alternative embodiment, the corrosion rate determined in the fourth determination step E6 can be modulated by at least one parameter dependent on the climate or climatic conditions in which the aircraft are likely to fly.

[0066] The fifth determination step E7 is intended to be implemented to determine a proposed inspection frequency for each of the risk zones 19 from its corrosion rate and a predetermined limit depth Ec of each of the risk zones 19. Each fuselage part 4 may have a predetermined limit depth Ec different from the other fuselage parts 4. This predetermined limit depth Ec may depend on a limit thickness of the part 4 considered or on a minimum thickness authorized for the corrosion of the part 4 considered.

[0067] The fifth determination step E7 may comprise the following sub-steps: - a third calculation sub-step E71 implemented by a third sub-unit of calculation COMP3 171, - a determination sub-step E72 implemented by a determination sub-unit DET 172.

[0068] The third calculation sub-step E71 is intended to be implemented to calculate the inspection frequency necessary for each of the risk zones 19 so that the corrosion depth Eb reaches the predetermined limit depth Ec.

[0069] The determination sub-step E72 is intended to be implemented to determine the inspection frequency proposal. The inspection frequency proposal is strictly lower than the inspection frequency necessary for each of the risk zones 19 so that the corrosion depth Ea reaches the predetermined limit depth Ec.

[0070] The transmission step E8 is intended to be implemented to transmit to a user device USER 20 (USER for “user device” in English) the proposed inspection frequency of each of the risk zones 19.

[0071] The user device 20 may comprise a display device intended to display the digital twin 2 accompanied by the proposed inspection frequency of each of the risk zones 19.

[0072] As an example, [Fig.5] represents two curves Vcl and Vc2 of the evolution of the corrosion depth Eb (for example in millimeters) as a function of time t (for example in years). The line Ec represents the predetermined limit depth. A different evolution can be noted between the two curves Vcl and Vc2. This difference in evolution corresponds to a modulation of the corrosion rate thanks to the parameter(s) dependent on the climate or the climatic conditions in which the aircraft are likely to fly. It can also be noted that a proposal for an inspection frequency greater than t0 may be too high to avoid the predetermined limit depth being reached. Indeed, at t0, the curves join a point 5 above the predetermined limit depth Ec.Furthermore, depending on the evolution of the corrosion depth Eb, the inspection frequencies may be different depending on the modulation parameter(s) dependent on the climate or climatic conditions in which the aircraft are likely to fly. For example, if we have an evolution of the corrosion depth Eb according to the curve Vcl, we can have a higher inspection frequency proposal at tl than if we have an evolution of the corrosion depth Eb according to the curve Vc2 which is at t2.

[0073] The invention also relates to a system S for optimizing maintenance of an aircraft fuselage 1 AC against corrosion ([Fig.6]). The system S can be implemented by a processor of a calculator, such as a computer.

[0074] The optimization system S comprises: - the collection unit 10 for collecting a plurality of corrosion incidents 6 on a plurality of AC aircraft, - the reporting unit 12 for reporting the plurality of corrosion incidents 6 collected on the digital twin 2 simulating a fuselage comprising at least one fuselage part 4, - the first determination unit 13 for determining areas and corrosion incident rates in each of the areas 71, 73 for each part 4 of the fuselage of the digital twin 2, - the second determination unit to determine risk areas 19, - the third determination unit 15 for determining a corrosion depth Eb for each fuselage part 4 located in each of the risk zones 19 from the remaining thickness Ea, - the fourth determination unit 16 for determining a corrosion rate for each of the risk zones 19 from the corrosion depth Eb and the age of the aircraft AC for each fuselage part 4 comprising a risk zone 19, - the fifth determination unit 17 for determining a proposed inspection frequency for each of the risk zones 19 from its corrosion rate and a predetermined limit depth Ec of each of the risk zones 19, - the transmission unit 18 for transmitting to a user device 20 the proposed inspection frequency for each of the risk zones 19.

[0075] The first determination unit 13 may comprise: - the first cutting sub-unit 131 for cutting each fuselage part 4 of the digital twin 2 according to a mesh of zones 70 comprising zones 71 of predetermined size, - the first calculation sub-unit 132 for calculating a corrosion incident rate for each of the zones 71 of the zone mesh 70.

[0076] The first determination unit 13 may further comprise: - the second cutting sub-unit 133 for cutting the fuselage part 4 according to a sub-mesh of zones 72 comprising zones 73 of predetermined size smaller than the predetermined size of the zones 71 of the zone mesh 70, - the second calculation sub-unit 134 for calculating a corrosion incident rate for each of the zones 73 of the zone sub-mesh 72.

[0077] Furthermore, the fifth determination unit 17 may comprise: - the third calculation sub-unit 172 for calculating the inspection frequency required for each of the risk zones 19 so that the corrosion depth Eb reaches the predetermined limit depth Ec, - determination subunit 172 to determine the inspection frequency proposal.

[0078] The optimization system S may comprise the database 11 in which the plurality of corrosion incidents 6 are stored. However, according to another embodiment, the database may be comprised by another system distinct from the optimization system S.

Claims

1. Claims Method for optimizing maintenance of an aircraft structure against corrosion, the aircraft structure comprising at least one aircraft structure part, characterized in that it comprises the following steps: - a collection step (El) implemented by a collection unit (10) for collecting a plurality of corrosion incidents (6) on a plurality of aircraft (AC), each of the corrosion incidents (6) comprising a position of the corrosion incident (6), a remaining thickness (Ea) of the part (4) of the aircraft structure at the position of the corrosion incident (6) and an age of the aircraft (AC) for which the corrosion incident (6) was collected, - a reporting step (E2) implemented by a reporting unit (12) to report the plurality of corrosion incidents (6) collected on a digital twin (2) virtually defining an aircraft structure comprising at least one aircraft structure part (4), - a first determination step (E3) implemented by a first determination unit (13) to determine zones (71, 73) and corrosion incident rates in each of the zones (71, 73) for each part (4) of the aircraft structure of the digital twin (2), the corrosion incident rate of each of the zones (71, 73) being equal to a ratio between the number of corrosion incidents (6) collected in each of the zones (71, 73) and a number of aircraft (AC) of the plurality of aircraft (AC) on which the plurality of corrosion incidents (6) were collected, - a second determination step (E4) implemented by a second determination unit (14) to determine risk zones (19), the risk zones (19) corresponding to the zones whose corrosion incident rate is greater than or equal to a predetermined corrosion incident rate, - a third determination step (E5) implemented by a third determination unit (15) to determine a corrosion depth (Eb) for each part (4) of the aircraft structure located in the risk zones (19) to from the remaining thickness (Ea), - a fourth determination step (E6) implemented by a fourth determination unit (16) to determine a corrosion rate for each of the risk zones (19) from the corrosion depth (Eb) and the age of the aircraft for each part (4) of the aircraft structure comprising a risk zone (19), - a fifth determination step (E7) implemented by a fifth determination unit (17) to determine a proposed inspection frequency for each of the risk zones (19) from its corrosion rate and a predetermined limit depth (Ec) of each of the risk zones (19), - a transmission step (E8) implemented by a transmission unit (18) to transmit to a user device (20) the proposed inspection frequency for each of the risk zones (19).

2. Method according to claim 1, characterized in that the first determination step (E3) comprises the following sub-steps: - a first cutting sub-step (E31) implemented by a first cutting sub-unit (131) for cutting each part (4) of the aircraft structure of the digital twin (2) according to a zone mesh (70) comprising zones (71) of predetermined size, - a first calculation sub-step (E32) implemented by a first calculation sub-unit (132) for calculating a corrosion incident rate for each of the zones (71) of the zone mesh (70).

3. Method according to claim 2, characterized in that the first step (E3) of determination further comprises the following sub-steps implemented if at least two zones (71) of the mesh of zones (70) of a part (4) of the aircraft structure has a difference in corrosion incident rate su- greater than a predetermined difference: - a second cutting sub-step (E33) implemented by a second cutting sub-unit (133) for cutting the part (4) of the aircraft structure according to a sub-mesh of zones (72) comprising zones (73) of predetermined size smaller than the predetermined size of the zones (71) of the mesh of zones (70), - a second calculation sub-step (E34) implemented by a second calculation sub-unit (134) for calculating a corrosion incident rate for each of the zones (73) of the sub-mesh of zones (72).

4. Method according to one of claims 1 to 3, characterized in that the corrosion depth (Eb) of a part (4) of the aircraft structure determined in the third determination step (E5) is equal to a difference between a nominal thickness (E) of the part (4) of the aircraft structure and the remaining thickness (Ea) of the part (4) of the aircraft structure.

5. Method according to one of claims 1 to 4, characterized in that the corrosion rate of each of the risk zones (19) determined in the fourth determination step (E6) is equal to a ratio between the average corrosion depth (Eb) in each of the risk zones (19) over a time after which this corrosion depth (Eb) is reached.

6. Method according to one of claims 1 to 5, characterized in that the fifth determination step (E7) comprises the following sub-steps: - a third calculation sub-step (E71) implemented by a third calculation sub-unit (171) to calculate the inspection frequency necessary for each of the risk zones (19) so that the corrosion depth (Eb) reaches the predetermined limit depth (Ec), - a determination sub-step (E72) implemented by a determination sub-unit (172) to determine the inspection frequency proposal, the inspection frequency proposal being strictly lower than the inspection frequency necessary for each of the risk zones (19) so that the corrosion depth (Ea) reaches the predetermined limit depth (Ec).

7. System for optimizing maintenance of an aircraft structure against corrosion, the aircraft structure comprising at least one aircraft structure part, characterized in that it comprises: a collection unit (10) for collecting a plurality of corrosion incidents (6) on a plurality of aircraft (AC), each of the corrosion incidents (6) comprising a position of the corrosion incident (6), a remaining thickness (Ea) of the part (4) of the aircraft structure at the position of the corrosion incident (6) and an age of the aircraft (AC) for which the corrosion incident (6) was collected, a reporting unit (12) for reporting the plurality of corrosion incidents (6) collected on a digital twin (2) virtually defining an aircraft structure comprising at least one part (4) of the aircraft structure, a first determination unit (13) for determining areas and corrosion incident rates in each of the areas (71, 73) for each part (4) of the aircraft structure of the digital twin (2), the corrosion incident rate of each of the areas (71, 73) being a value of the corrosion incident rate of the aircraft structure.73) being equal to a ratio between the number of corrosion incidents (6) collected in each of the zones (71, 73) and a number of aircraft (AC) of the plurality of aircraft (AC) on which the plurality of corrosion incidents (6) were collected, a second determination unit for determining risk zones (19), the risk zones (19) corresponding to the zones (71, 73) whose corrosion incident rate is greater than or equal to a predetermined corrosion incident rate, a third determination unit (15) for determining a corrosion depth (Eb) for each part (4) of the aircraft structure located in each of the risk zones (19) from the remaining thickness (Ea), a fourth determination unit (16) for determining a corrosion rate for each of the risk zones (19) from the corrosion depth (Eb) and the age of the aircraft (AC) for each part (4) of the aircraft structure comprising a risk zone (19), a fifth determination unit (17) for determining a proposed inspection frequency for each of the risk zones (19) from its corrosion rate and a predetermined limit depth (Ec) of each of the risk zones (19), a transmission unit (18) for transmitting to a user device (20) the proposed inspection frequency of each of the risk zones (19).

8. System according to claim 7, characterized in that the first determination unit (13) comprises: - a first cutting sub-unit (131) for cutting each part (4) of the aircraft structure of the digital twin (2) according to a mesh of zones (70) comprising zones (71) of predetermined size, - a first calculation sub-unit (132) for calculating a corrosion incident rate for each of the zones (71) of the mesh of zones (70).

9. System according to claim 8, characterized in that the first determination unit (13) further comprises: - a second cutting sub-unit (133) for cutting the part (4) of the aircraft structure according to a sub-mesh of zones (72) comprising zones (73) of predetermined size smaller than the predetermined size of the zones (71) of the zone mesh (70), - a second calculation sub-unit (134) for calculating a corrosion incident rate for each of the zones (73) of the sub-mesh of zones (72).

10. System according to one of claims 7 to 9, characterized in that the fifth determination unit (17) comprises: - a third calculation sub-unit (172) for calculating the inspection frequency required for each of the risk zones (19) so that the corrosion depth (Eb) reaches the predetermined limit depth (Ec), - a determination sub-unit (172) for determining the inspection frequency proposal, the inspection frequency proposal being strictly lower than the inspection frequency necessary for each of the risk zones (19) so that the corrosion depth (Ea) reaches the predetermined limit depth (Ec).

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