Method for inspecting an aeronautical part

Abstract

Method for inspecting an aeronautical part, such as an aircraft turbine-engine cowl (10), comprising: a) a step of performing a three-dimensional scan of a surface (12) of the part, so as to obtain a digitised three-dimensional image of the surface and of its defects, b) a computerised step of analysing the three-dimensional image, and in particular the defects, c) a computerised step of determining a plurality of defect-related dimensional parameters, d) a computerised step of calculating an overall criticality of the defects, by comparing the calculated dimensional parameters with reference values for these dimensional parameters, and e) a step of evaluating the part, based on the calculated overall criticality, in order to determine whether the part is compliant or non-compliant.

Description

[0001] DESCRIPTION

[0002] TITLE: METHOD FOR INSPECTING AN AERONAUTICAL COMPONENT

[0003] Technical field of the invention

[0004] The present invention relates to a method for inspecting an aeronautical part, such as an aircraft turbomachine housing.

[0005] Technical background

[0006] The technical background includes documents FR-A1-3 141 245 and US-A1-2014 / 020485.

[0007] Aeronautical parts generally require inspection to verify their conformity. This inspection can take place on a new part after its production, or on a part that has already been used and mounted, for example on a turbomachine, in which case the inspection usually takes place during a maintenance operation.

[0008] This is particularly true of a fan casing on an aircraft turbomachine. A fan casing is an annular-shaped housing that surrounds the turbomachine's fan. During operation, the casing is susceptible to projectiles such as birds, which can cause impacts on its internal surface. These impacts create defects in the form of dents. During maintenance, the fan casing is inspected to detect these defects and assess their severity.

[0009] In this application, "criticality" (or overall criticality) of a defect or defects means a scale for measuring the impact of a failure and therefore the level of acceptability of a risk.

[0010] In current technology, this inspection is performed visually by a specialized operator. This makes the inspection relatively lengthy and complex. Furthermore, such an inspection carries a risk of misjudgment, particularly due to operator eye strain. The longer the inspection, the greater the maintenance and engine downtime, and consequently, the higher the maintenance costs.

[0011] Therefore, there is a need to find a solution to improve the reliability and speed up this type of inspection and control. A tomographic analysis of a turbomachine component has already been proposed. However, this analysis requires a relatively expensive tomography system. Furthermore, while tomography is useful for identifying potential internal defects, it is not necessarily easy to use for identifying potential surface defects.

[0012] The invention provides a solution to this need, which is simple, effective and economical.

[0013] Summary of the invention

[0014] The invention relates to a method for inspecting an aeronautical part, such as an aircraft turbomachine housing, comprising:

[0015] a) a step of performing a three-dimensional scan of a surface of the aeronautical part, this surface having defects such as hollows, in order to obtain a digitized three-dimensional image of the surface and its defects in the form of a multitude of surface points, called for example a point cloud, b) a computerized step of analyzing the three-dimensional image, and in particular the defects,

[0016] c) a computerized step for determining several dimensional parameters related to defects,

[0017] d) a computerized step for calculating the overall criticality of defects, by comparing the determined dimensional parameters with corresponding reference values ​​for these dimensional parameters, and

[0018] e) a step of evaluating the part, based on the calculated overall criticality, in order to determine whether the part is compliant or non-compliant,

[0019] said process being characterized in that, at step d), the reference values ​​are contained in a pre-established nomogram, said nomogram being in the form of a graph with several curves, each curve representing an evolution of the weighting (in %) of the criticality of one of the parameters as a function of the value of that parameter.

[0020] The invention relates to an inspection method in which several steps can be computerized and thus automated, to accelerate and improve the reliability of the inspection. In this application, "computerized" means that a step is performed by a computer system. The computer system is then configured to control the execution of the step by, for example, controlling the various equipment necessary for its completion. Step a) of the method consists of 3D scanning the surface of the aeronautical part to be inspected. This produces a 3D image of the surface in the form of a point cloud, the points being surface points such that the point cloud represents the relief or profile of this surface with its defects.

[0021] Step b) of the process consists in particular of analyzing the point cloud for example to distinguish the primary defects to be analyzed in more detail.

[0022] Step c) of the process allows several dimensional parameters of the defects to be determined, such as depth, length, etc.

[0023] Step d) of the process calculates the overall criticality of the defects, and step e) determines whether the aeronautical part conforms or does not conform based on this overall criticality. Step e) can be performed by an operator. The process according to the invention may include one or more of the following features, taken individually or in combination:

[0024] - step a) is carried out on a limited area of ​​the part, called the inspection area; -- the inspection area has a parallelogram shape and in particular a square shape; -- the inspection area has dimensions of 25cm x 25cm;

[0025] -- any defects detected outside the inspection area are ignored;

[0026] -- the scan is done by laser;

[0027] -- the inspection area includes a number of points greater than 100, and for example between 200 and 800;

[0028] - step a) is preceded by a step i) of visual inspection, preferably complete, of the surface of the part so as to determine one or more inspection areas, the inspection area or areas having defects;

[0029] - step b) includes the detection, among all the defects, of certain defects called primary defects;

[0030] - Primary defects are defects that have a depth greater than or equal to a reference depth previously determined, for example before the implementation of the process;

[0031] -- the reference depth is between 0.1 and 2mm, preferably between 0.2mm and 1mm, and is for example equal to 0.5mm; - step b) includes the distribution of primary defects in reference surfaces, called islands, each of the islands having one or more adjacent primary defects;

[0032] - in step c), the dimensional parameters of the primary defects are chosen from the depth of each primary defect, the length of each primary defect, and the minimum distance between two adjacent primary defects;

[0033] -- the dimensional parameters are determined in or from a reference plane that is parallel to the surface of the part or tangent to the surface of the part at the level of the primary defect considered;

[0034] -- the primary defects are numbered and each associated with a number;

[0035] - in step d), a weighting is assigned to each of the dimensional parameters according to the results of the comparison with the corresponding reference values ​​for these dimensional parameters;

[0036] - for each of the primary defects, the weights of all the dimensional parameters are added together to determine a criticality of the defect, this criticality being expressed for example as a percentage;

[0037] - the overall criticality of the defects is determined from the criticalities of all the primary defects;

[0038] -- the weightings of all dimensional parameters are added together or averaged to determine the criticality of each primary defect;

[0039] -- criticality is expressed as a percentage;

[0040] -- the criticality of primary defects is averaged to calculate the overall criticality of the inspection area or part under consideration;

[0041] - step e) is carried out, preferably by an operator, by comparing the calculated overall criticality with a reference criticality;

[0042] - the aeronautical part is an annular fan housing for an aircraft turbomachine;

[0043] - the process includes a step iii) of registering the three-dimensional image in a digital model of the aeronautical part, called a digital double, so as to be able to visualize the multitude of points on the digital double of the aeronautical part;

[0044] -- the process includes a step ii) of entering identity information relating to the document; - steps b), c) and d) are carried out automatically and allow an automated control report to be obtained at the end of step d), which is used in step e);

[0045] -- steps b), c) and d) are carried out using Polyworks® software.

[0046] The present invention also relates to an installation for the implementation of a process as described above, characterized in that it comprises a three-dimensional scanner configured to carry out step a) of the process, and a computer system configured to carry out at least steps b) to d) and to control the display of the calculated overall criticality.

[0047] The present invention further relates to a computer program downloadable from a communication network and / or stored on a medium readable by a computer system, characterized in that it comprises instructions for, when said program is executed on a computer system:

[0048] - order a three-dimensional scanner in order to carry out step a) of the process as described above, then

[0049] - carry out at least steps b), c) and d) of said process and command the display of the calculated overall criticality.

[0050] Brief description of the figures

[0051] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the accompanying drawings in which:

[0052] [Fig.1] Figure 1 is a flowchart showing steps of a process according to the invention for controlling an aeronautical part;

[0053] [Fig.2] Figure 2 is a schematic perspective view of an aeronautical part and in particular of a fan housing;

[0054] [Fig.3] Figure 3 is a larger scale view of part of Figure 2 and shows defects on a surface of the part;

[0055] [Fig.4] Figure 4 schematically shows a cloud of points as defined in the invention;

[0056] [Fig.5] Figure 5 is a schematic view of an inspection area;

[0057] [Fig.6] Figure 6 is a schematic view of an identification card for part identification; [Fig.7] Figure 7 is a very schematic view of an inspection area with defects and illustrates a step in the process;

[0058] [Fig.8] Figure 8 is a very schematic view of an inspection area with defects and illustrates one step of the process;

[0059] [Fig.9] Figure 9 is a very schematic view of defects and illustrates one step of the process;

[0060] [Fig. 10] Figure 10 is a table listing dimensional parameters of primary defects as well as the criticality of each of these primary defects; and

[0061] [Fig.11] Figure 11 is a schematic view of an installation for implementing the process according to the invention.

[0062] Detailed description of the invention

[0063] Figure 1 is a flowchart that schematically shows an embodiment of a method for controlling an aeronautical part according to the invention.

[0064] The aeronautical component is, for example, a casing, in particular a fan casing, for an aircraft turbomachine. Figures 2 and 3 illustrate such a fan casing 10 (also referred to as "casing 10" in this description). The casing 10 has a generally annular shape around an axis A. This casing 10 includes an internal surface 12 that may have defects 14 such as impacts, which must be detected and analyzed during the casing 10 inspection process (Figure 3).

[0065] The control process essentially comprises 5 steps, noted as steps a) to e), and may include other optional steps noted i), ii), etc.

[0066] Step a) of the inspection process is a step of carrying out a three-dimensional (3D) scan of a surface of the part, such as the surface 12 of the housing 10, this surface having defects such as hollows, so as to obtain a digitized three-dimensional image of the surface and its defects in the form of a multitude of surface points, called a point cloud 20.

[0067] Figure 4 shows a scatter plot of 20 points that can be obtained at the end of this step a).

[0068] Step a) is preferably performed on a limited area of ​​the part, called the inspection zone. In the case of the housing in Figures 2 and 3, for example, only an inspection zone Z of the surface can be inspected according to the method. It is therefore understood that only this inspection zone Z is scanned in step a). The inspection zone Z preferably has a simple geometric shape so that it can be easily delimited. Preferably, the inspection zone Z has the shape of a parallelogram, and in particular a square.

[0069] The inspection zone Z, for example, has dimensions of 25 cm x 25 cm (centimeters).

[0070] 3D scanning is preferably performed using a laser, and in particular by laser line(s). For example, it could involve at least one laser line that scans the surface to be inspected and automatically records different points on the surface.

[0071] The 3D scan is preferably carried out using a 3D scanner such as the one marketed by the company FARO under the name Probe Laser Liben FAROBIu xR.

[0072] The 3D scan thus allows the creation of a point cloud corresponding to the relief or profile of the surface to be inspected. If points are detected outside the inspection zone Z, these points can be ignored to limit the analysis of defects within this inspection zone Z.

[0073] Figure 5 shows, for example, the inspection zone Z and some points that are located outside (around) this zone Z and will be ignored.

[0074] The Z inspection zone can include a number of points greater than 100, and for example between 200 and 800.

[0075] As can be seen in Figure 1, the inspection process may include, prior to step a), a step i) of visual inspection, preferably complete, of the surface of the part so as to determine one or more inspection areas, the inspection area or areas having defects.

[0076] In the case of the housing 10 for example, it is understood that the operator visually checks the entire surface 12 before step a). During this inspection, he will detect defects and will decide which inspection zone Z or which inspection zones Z containing defects will / will have to be subject to a more thorough inspection according to steps a) and following.

[0077] The process may include, for example, before step a), a step ii) of entering identification information relating to the part. This information allows the part to be identified and traced. In the case of the housing 10, this could, for example, be a reference number for this housing, a reference number for the turbomachine incorporating this housing, information on the aircraft equipped with this turbomachine, information on the airline operating this aircraft, etc. An identification record 30 for the part is then obtained, preferably in computerized form.

[0078] Figure 6 illustrates such an identity card 30 which can be directly completed by an operator via a computer system.

[0079] The process may include, for example after step a), a step iii) of registration of the three-dimensional image (point cloud) in a digital model of the part, called a digital twin, so as to be able to view the point cloud on the digital twin of the part.

[0080] This step is particularly advantageous for building a digital library of the most frequently inspected areas of a part, and therefore the areas most often exhibiting defects. The digital library allows for the storage of feedback from previous inspections, which can facilitate and accelerate step i) mentioned above, for example.

[0081] Figure 2 can be considered as illustrating this step iii). This figure allows visualization of the position and dimensions of the inspection zone Z on the housing 10. Step iii) is carried out via a computer system.

[0082] The control process then includes several steps b), c) and d) also carried out by a computer system and which allow for detailed analysis of the point cloud obtained in step a).

[0083] Step b) is a computerized step of three-dimensional image analysis, and in particular of defects.

[0084] Step b) may, for example, include the detection of primary defects among all the defects. Primary defects are, for example, defects that have a depth P (visible in Figure 7, for example) greater than or equal to a previously determined reference depth. The reference depth may be between 0.1 and 2 mm (millimeters), preferably between 0.2 mm and 1 mm, and is, for example, on the order of 0.5 mm.

[0085] Figure 7 schematically illustrates some defects 14 in an inspection zone Z. Among these defects 14, some have a depth P greater than the reference depth Pref, and others do not. The primary defects (referenced 14' in Figure 7) having a depth greater than the reference depth will be analyzed in more detail later.

[0086] Step b) may involve the distribution or assignment of primary defects to reference surfaces, called islands 22, each island containing one or more adjacent primary defects (Figure 8). Using these islands can simplify the analysis of defects due to their distribution across reference surfaces.

[0087] Put another way, the dimensional parameters of the primary defects of each island can be determined with respect to the reference surface of that specific island and, in general, the steps implemented in the rest of the process can be limited to the islands without having to treat the entire inspection area Z.

[0088] Step c) is a computerized step for determining several dimensional parameters relating to defects, in particular primary defects.

[0089] In step c), the dimensional parameters of the primary defects can be chosen from the depth P of each primary defect, the length L of each primary defect, and the minimum distance Dmin between two adjacent primary defects (Figure 9). Other dimensional parameters or different dimensional parameters could, of course, be measured.

[0090] These dimensional parameters are preferably determined in or from a reference plane Q which is parallel to the surface 12 of the part or tangent to the surface of the part at the level of the primary defect considered (figure 9).

[0091] Step c) is advantageously carried out for each of the 22 islands identified in step b).

[0092] Primary defects can be numbered and each associated with a number X1, X2, etc., to identify and list them (figure 9).

[0093] Step d) is a computerized step of calculating an overall criticality C of the defects, by comparing the dimensional parameters (P, L, Dmin, etc.) determined with reference values ​​for these dimensional parameters.

[0094] The reference values ​​are preferably contained in a pre-established nomogram. For the determination of overall criticality, a weighting can be assigned to each of the dimensional parameters based on the results of the comparison with the reference values.

[0095] This weighting can be obtained using a nomogram, for example, presented as a graph with several curves, each curve representing the percentage weighting of a parameter's criticality as a function of that parameter's value. For a given parameter, this type of nomogram thus provides the criticality weighting for each measured dimensional parameter. The weightings of all dimensional parameters can then be added or averaged to determine the criticality C of each primary defect. This criticality is, for example, expressed as a percentage.

[0096] Figure 10 illustrates an example of criticality C of each of the primary defects in an inspection zone Z, as a function of the comparison of the dimensional parameters (P, L, Dmin, etc.) determined with the reference values ​​of a nomogram.

[0097] The criticality values ​​C in the table in Figure 10 are averaged, for example, to calculate the overall criticality of the inspection area or part under consideration. Alternatively, the maximum criticality C in the table in Figure 10 could be used as the overall criticality of the inspection area or part under consideration. In this particular case, the average criticality is approximately 2.60% and the maximum criticality is 3.56%.

[0098] The process may include a step (iv) of displaying the overall criticality calculated in step (d), for example on a computer system screen. All or part of the information useful for calculating the criticality may be displayed, and for example, the information contained in the table in Figure 10.

[0099] The process finally includes a step e) of evaluating the part, based on the calculated overall criticality, to determine whether the part is compliant or non-compliant. Step e) can be performed by an operator by comparing the calculated overall criticality with a reference criticality.

[0100] For example, if the criticality of each defect in a part should not exceed 4%, the area inspected based on the data in Figure 10 could be considered compliant because the criticality of all defects is less than 4%. If the inspected area is the only area of ​​the part, then the part can be declared compliant. If the part has other areas to be inspected, it must also be ensured that the criticality of the primary defects in these other areas is also less than 4%.

[0101] As mentioned above, steps b), c) and d) are preferably carried out automatically and allow an automated control report to be obtained at the end of step d), which is used in step e). These steps b), c) and d) are carried out for example using Polyworks® software.

[0102] The present invention also relates to an installation 30 for implementing the control method according to the invention, as illustrated in Figure 11. The installation 30 comprises a three-dimensional scanner 32 configured to perform step a) of the method, and a computer system 34 configured to perform at least steps b) to d) and control the display on a screen 36 of the calculated criticality C. The computer system 34 comprises, for example, a processor (which enables the implementation of at least certain steps of the control method), a memory (which enables, for example, the storage of reference values), etc.

[0103] The invention further relates to a computer program downloadable from a communication network and / or stored on a computer-readable medium. This computer program includes instructions for, when said program is executed on the computer system 34:

[0104] - order the three-dimensional scanner 32 in order to carry out step a) of the control process, then

[0105] - carry out at least steps b), c) and d) of the control process and command the display of the calculated criticality.

Claims

DEMANDS 1. A method for inspecting an aeronautical component, such as an aircraft turbomachine housing (10), comprising: a) a step of carrying out a three-dimensional scan of a surface (12) of the aeronautical part, this surface having defects (14) such as hollows, so as to obtain a digitized three-dimensional image of the surface and its defects in the form of a multitude of surface points, b) a computerized step for analyzing the three-dimensional image, and in particular the defects, c) a computerized step for determining several dimensional parameters related to defects, d) a computerized step for calculating the overall criticality of defects, by comparing the determined dimensional parameters with corresponding reference values ​​for these dimensional parameters, and e) a step of evaluating the part, based on the calculated overall criticality, in order to determine whether the part is compliant or non-compliant, said process being characterized in that, at step d), the reference values ​​are contained in a pre-established nomogram, said nomogram being in the form of a graph with several curves, each curve representing an evolution of the weighting (in %) of the criticality of one of the parameters as a function of the value of that parameter.

2. Method according to claim 1, wherein step a) is carried out on a limited area of ​​the part, called inspection zone (Z).

3. Method according to claim 1 or 2, wherein step a) is preceded by a step i) of visual inspection of the surface (12) of the part so as to determine one or more inspection zones (Z), the inspection zone or each inspection zone having defects.

4. A method according to any one of the preceding claims, wherein step b) comprises the detection, among all the defects, of certain defects called primary defects.

5. Method according to claim 4, wherein the primary defects are the defects which have a depth (P) greater than or equal to a previously determined reference depth (Pref).

6. Method according to claim 4 or 5, wherein, in step c), the dimensional parameters of the primary defects are chosen from the depth (P) of each primary defect, the length (L) of each primary defect, and the minimum distance (Dmin) between two adjacent primary defects.

7. A method according to any one of the preceding claims, wherein, in step d), a weighting is assigned to each of the dimensional parameters based on the results of the comparison with the corresponding reference values ​​for these dimensional parameters.

8. A method according to claim 7, wherein, for each of the primary defects, the weights of all the dimensional parameters are added together to determine a criticality of the defect, this criticality being expressed for example as a percentage.

9. A method according to claim 8, wherein the overall criticality of the defects is determined from the criticalities of all the primary defects.

10. A method according to any one of the preceding claims, wherein step e) is carried out by comparing the calculated global criticality with a reference criticality.

11. A method according to any one of the preceding claims, wherein the aeronautical part is an annular fan housing for an aircraft turbomachine.

12. A method according to any one of the preceding claims, wherein it includes a step iii) of registering the three-dimensional image in a digital model of the aeronautical part, called a digital twin, so as to be able to visualize the multitude of points on the digital twin of the aeronautical part.

13. A method according to any one of the preceding claims, wherein steps b), c) and d) are carried out automatically and allow an automated control report to be obtained at the end of step d), which is used in step e).

14. Installation (30) for carrying out a process according to one of the preceding claims, characterized in that it comprises a three-dimensional scanner (32) configured to carry out step a) of the process, and a computer system (34) configured to carry out at least steps b) to d) and to display the calculated overall criticality.

15. A computer program downloadable from a communication network and / or stored on a medium readable by a computer system, characterized in that that it includes instructions for, when said programme is run on a computer system (34): - order a three-dimensional scanner (32) in order to carry out step a) of the process according to one of the preceding claims, then - carry out at least steps b), c) and d) of said process and command the display of the calculated overall criticality.

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