INSPECTION PROCEDURES AND SYSTEM

Description

[0001] The present invention relates to an on-wing inspection method according to the preamble of patent claim 1 and a system for carrying out such an inspection method.

[0002] Devices such as power machines, such as turbomachines, are usually equipped with a variety of sensors, such as temperature sensors and vibration sensors, to monitor the condition of invisible machine components inside the machine. If, for example, a temperature sensor on the high-pressure turbine side registers an overtemperature, a corresponding warning message is issued in the cockpit of aircraft engines. To determine whether the aircraft engine has been damaged by the overtemperature, the engine is removed from the wing and disassembled at component level. A destructive metallographic microstructure analysis is then performed on the first high-pressure turbine stage. Using microsection standards, the microstructure changes of the high-pressure turbine blade are assessed at three locations.To account for normal, aging-related effects on the microstructure, a micrograph is also taken from non-overheated areas of the test blade, such as the blade root, to evaluate changes in the center of the blade. If unacceptable damage to the component is detected, all blades in that stage must be replaced, and the inspection is continued for a subsequent turbine stage. However, it has been shown that in approximately 80% of cases, no damage to the blade material occurred due to excessive temperatures.

[0003] To date, various methods for testing the condition of components not visible outside a device by means of different test heads, in particular adapted for the respective purposes, are known, some of which have signal processing devices and test heads in various designs for carrying out different inspection methods. Such methods or aspects of such methods and devices for this purpose are described, for example, in the documents US 2012 / 158319 A1, DE 10 2006 048791 A1, DE 11 2014 000505 T5, US 4 139 822 A, US 2017 / 006201 A1, JP H07 270261 A, US 5 301 061 A, US 2004 / 051525 A1, US 20143 / 060289 A1, US 2015 / 192499 A1, DE 10 2016 224 049 A1.

[0004] Furthermore, document US 2017 / 241286 A1 discloses a method for detecting a distortion in a component of a gas turbine engine, EP 3 171 166 A1 discloses a method for checking a component of a device that is not visible from the outside, and US 2014 / 260755 A1 discloses multi-unit robot arms for air applications, wherein the robot arm can be used for the in-situ repair of an internal component of a gas turbine engine.

[0005] The object of the invention is to create an on-wing inspection method that reduces inspection effort. Furthermore, the object of the invention is to create a system that enables the on-wing inspection method to be carried out.

[0006] This object is achieved by an on-wing inspection method having the features of patent claim 1 and by a system having the features of patent claim 10.

[0007] An on-wing inspection method according to the invention for checking the condition of a component that is not visible from the outside, and in particular a component or component area of ​​a device that is not accessible from the outside, involves the use of a borescope. In a first step, a non-destructive testing method is applied in which a physical property of at least one component area is recorded. In a subsequent step, a comparison is made between an actual physical value recorded by the non-destructive testing method and a physical reference value of the component area. The reference value is read from a database and takes into account any aging of the component. In a further step, a deviation of the actual value from the reference value is then evaluated.

[0008] The on-wing inspection method according to the invention makes a reliable and clear decision as to whether a complex conventional inspection, such as opening the device with, for example, a destructive metallographic material examination of individual components, is necessary. It has been recognized that a structural change in the component or the component material can be detected not only by means of a metallographic examination or, more generally, by means of a materialographic examination, but that the structural change also affects the physical properties of the component, which can be detected by appropriate physical measurement methods. The term "materialographic examination" also includes micrograph examinations of components that are not metallic in nature, such as components made of fiber-reinforced plastics.It thus encompasses the term "metallographic examination," which literally only encompasses examinations of metallic components. A borescope-based non-destructive testing of changes in one or more physical properties enables the component to be examined with the fixture closed and thus with the fixture mounted. Unnecessary disassembly of the fixture is avoided. Taking aging into account ensures reliable test results, as a deviation in the measured physical property is not related to a new part, which simply shows no signs of aging, but rather to a used component with the same or at least a similar history. The aging of the component or component material results, for example, from temperature events during flight operation, such as temperature profiles and peak temperatures, operating time, engine operating point, ETM data, and the like.This significantly reduces inspection effort. The comparison and evaluation are preferably automated, so that the person performing the inspection process only needs to select the borescope with a test head and position it accordingly. The selection of the appropriate inspection method can be based on criteria such as the component material, component accessibility, and / or the component's previous history, and can also be automatically suggested to the user, taking these exemplary criteria into account. Examples of devices include power machines such as turbomachines, especially aircraft engines, industrial turbines, power plant turbines, and ship turbines.

[0009] The inspection effort is significantly reduced when using the inspection method according to the invention. The inspection method enables more reliable test results when multiple blades are quickly checked, thus providing a reliable statement about the condition of the respective component. In aircraft engines, unnecessary shop visits are avoided, and on-wing times are increased.

[0010] Preferred non-destructive testing methods include exposing at least one component region to a microwave field, an ultrasonic field, X-rays, or an eddy current. Other alternative or supplementary non-destructive testing methods include, without limitation, thermography analysis, vibration and resonance analysis, and / or conductivity measurements, particularly electrical conductivity measurements.

[0011] For X-ray inspections, accessibility to the component(s) from two sides is advantageous. For example, the X-ray tube can be guided through existing holes, such as those in the combustion chamber of turbomachines, which are used for injection nozzles, and X-ray detectors can be inserted and securely positioned through existing borescope openings in the turbomachine housing.

[0012] When conducting an eddy current test, for example, it is advisable to position the measuring head relative to the component in order to reproducibly define the measured material volume. Orienting and fixing the measuring head at the cooling air holes is particularly useful in this regard.

[0013] Another practical measurement method is process-compensated resonance testing (PCRT). This resonance analysis, using special high-frequency measurement technology and specialized analysis software, can detect even relatively small local changes in the component.

[0014] When performing an electrical conductivity measurement, the electrodes used to define the current path through the component can be designed so that current enters and exits, for example, via the cooling air holes. In particular, when using more than two measuring points, a cross-section measurement is possible, allowing for conclusions about an area.

[0015] The above-mentioned examples of non-destructive testing methods: X-ray testing, eddy current testing, resonance testing and conductivity measurement represent, for example, concrete applications on turbine blades in the installed state of turbomachinery.

[0016] If the assessment determines that the deviation is within a permissible tolerance range, one example provides for the component to be assessed as "OK." The inspection test can then be terminated or repeated for another component area or component to increase the safety and reliability of the test result.

[0017] If the assessment reveals that the deviation lies outside the permissible tolerance range, the component will preferably be subjected to a destructive materialographic examination. Alternatively, a further non-destructive test can be carried out using an alternative testing method. If the second testing method also shows an excessive or intolerable deviation between the measured actual value and the reference value, only then will the component be subjected to a destructive materialographic examination. However, if the second test shows a tolerable deviation, a third test can be carried out using a different non-destructive testing method than the first and second testing methods. If the third test then shows an intolerable deviation, only then will the component be subjected to a destructive materialographic examination.However, if the third test reveals a tolerable deviation, the component can be rated as "OK." These measures can prevent unnecessary destructive materialography testing.

[0018] If it is determined during the assessment that the deviation lies within a permissible tolerance range, one embodiment provides for the aforementioned steps (application of non-destructive testing method, comparison of values ​​and assessment) to be repeated at least once using a different non-destructive testing method for at least one previously inspected component area. This increases the safety, reliability and objectivity of the inspection process. The selection of the testing method for the so-called control test is, as with the initial test, preferably automated based on criteria such as component material, component accessibility and / or previous component history, supplemented by the criterion that the second testing method is different from the first testing method. It can be advantageous to also take into account the criterion that no two identical testing methods are used.For example, if the first test method was to measure electrical conductivity, it may be advantageous for the second test method to include a radiographic test. The comparison is preferably automated.

[0019] If, after repeating the aforementioned steps (application of non-destructive testing, value comparison, and evaluation), the assessment determines that the deviation is within a permissible tolerance range, one example provides for the component to be assessed as "OK." The assessment is preferably carried out automatically.

[0020] If, after repeating the aforementioned steps (application of non-destructive testing, comparison of values, and evaluation), the assessment reveals that the deviation lies outside the permissible tolerance range, one example provides for the device to be opened and the component to be subjected to a destructive materialography examination. Due to the negative result of the control test, the component is most likely defective, so it will likely need to be replaced.

[0021] In order to make a statement about the condition of a component area that is inaccessible to a borescope test head, one embodiment provides for the inaccessible component area to be assessed as "OK" if, after repeating steps a) to c), the assessment includes a determination that the deviation lies within a permissible tolerance range.

[0022] Preferably, the non-destructive testing methods to be applied are calibrated beforehand on reference components. Calibration is a preparatory measure and increases the reliability of the actual inspection procedure. The reference components may, for example, have different operating times, different maximum operating temperatures, and the like.

[0023] A system according to the invention, which is configured to carry out an on-wing inspection method according to the invention, has a computer unit and a test head. It is configured, in particular, for the automated selection of the non-destructive testing method, for the detection of the physical property itself, for the automated performance of the value comparison between the detected actual value and the reference value, and for the automated evaluation of a tolerance between the actual value and the reference value. The system allows for a reliable condition check of a component or component area located inside a device and not visible from the outside, and in particular not accessible from the outside. The system is mobile and preferably portable by a person carrying out the inspection method, so that it can be quickly brought to the respective site.

[0024] The system, comprising a computer unit and test head, is designed to perform on-wing inspections of engines. It has a particularly pincer-shaped design with multiple elements, with a main sensor located centrally on the test head. For example, the test head can be designed to be collapsible, so that when folded, it can be guided through borescope openings to areas subject to high thermal stress, for example on turbine blades such as the leading edge, or the center of the gas duct. A flexible, pincer-shaped design with multiple elements allows the area of ​​a component to be inspected, such as the leading edge of an airfoil, to be opened and optimally enclosed, even with different geometries. The centrally located main sensor can be adapted and / or replaced for different engine types or components, such as high-pressure turbine blades, if required.The lateral links serve to stabilize and fix the test head to the component.

[0025] In one version of the test head, the lateral elements have additional sensors in the form of rigid or movable test buttons in order to test, for example, areas behind the leading edge (internal structure of the blade) on turbine blades via the pressure and suction sides.

[0026] In one version of the test head, the test head is designed to be movable and interchangeable, in particular for carrying out several test procedures and for adapting the system to different test tasks.

[0027] In one embodiment, the test head is arranged on a flexible, rigid or stiffenable test head guide with integrated signal and / or control lines, which connect the test head in particular to the computer unit, and in one embodiment of the test head, a pivotable connection device is provided for connecting the test head to the test head guide in order to enable flexible mobility of the system when carrying out the inspection process.

[0028] In one version of the test head, cameras are provided on the connection device, which can be used in particular for guiding and positioning the test head and / or for carrying out measurements and for documenting the examination.

[0029] Other advantageous embodiments of the invention are the subject of further subclaims.

[0030] Preferred embodiments of the invention are explained in more detail below using highly simplified schematic representations. They show: Figure 1a side view of an example component to be inspected, Figure 2a top view of an area of ​​the Figure 1 shown component, Figure 3 shows a sequence of an inspection method according to the invention, and Figures 4a and 4b show an exemplary test head of a system according to the invention.

[0031] In the Figures 1 to 3 A preferred embodiment of an inspection method 1 according to the invention is explained using an exemplary component 2. The exemplary component 2 is shown in the Figures 1 and 2sketched and a turbine-side rotor blade 2 of a turbomachine such as an aircraft engine. The rotor blade 2 essentially has a blade root 4, an airfoil 6, and a platform 8 arranged between the blade root 4 and the airfoil 6. The airfoil 6 has a suction side 10 and an opposite pressure side 12, which are connected to each other via a leading edge 14 and a trailing edge 16.

[0032] The inspection method 1 according to the invention is to be applied by way of example in a blade-side component section 18, preferably in a component section 18 at half the height of the blade. For this purpose, a pressure-side front component region or inspection region 22 is defined in the blade-side component section 18. The component section 18 and the inspection region 22 can be defined almost arbitrarily, as long as they are accessible for subsequent non-destructive borescope-based testing and, in particular, for a borescope inspection head.

[0033] In Figure 3The sequence of inspection method 1 is now outlined. A borescope with a system according to the invention is required. The system comprises a computer unit and a corresponding probe for the borescope. The probe enables the application of the intended non-destructive testing methods. The database 105 can be part of the computer unit and thus represent a storage medium of the computer unit.

[0034] Before the actual inspection procedure 1 begins, preparatory measures 1.1 (steps 100 and 110) are performed, which enable repeated application of inspection procedure 1. The preparatory measures are performed at least once so that inspection procedure 1 can then be performed as often as desired. Essentially, the preparatory measures create a data set consisting of at least reference values ​​and preferably also reference-value-related tolerances or tolerance fields, which can be supplemented with calibration results from test procedures.

[0035] In step 100 (creating a database), a database 105 is created with reference values ​​from at least the component sections 18 of the component 2, in which the test areas 22, 24, 26, 28 are defined and which are to be examined for changes in their physical material properties as part of the borescope inspection process. The reference values ​​are obtained from reference components that have been in operation and / or are currently in operation and contain aging of the component material, which results, for example, from temperature events from flight operation such as temperature profiles and maximum temperatures, running times, engine operating points, ETM data, and the like. Each reference value is assigned a tolerance field in order to determine whether a deviation between the reference value and a measured actual value of the component or component material in the respective test area 22 is tolerable or intolerable.

[0036] In step 110 (calibration of test methods), possible non-destructive testing methods are then calibrated on the reference component. Examples of non-exhaustive test methods include measurements of electrical, magnetic, and / or thermal conductivity (eddy current, microwave, and thermography), vibration and resonance tests, penetration properties (X-rays and ultrasound), conductivity measurements, in particular, a conductivity measurement, and the like. The results of the calibration can also be written to the database 105.

[0037] The preparatory measures 1.1 for the actual inspection procedure 1 are thus completed. As soon as a warning message 120, such as an overtemperature, is generated by a corresponding sensor on the aircraft engine, the inspection procedure 1 proposes the steps explained below.

[0038] In step 130 (applying a test method with the fixture closed), a non-destructive testing method is selected, and a borescope is equipped with a corresponding test head. Preferably, the system suggests a preferred test method to the user. Criteria for the automated selection can include the component material, component accessibility, and / or previous component history.

[0039] In step 140 (comparison between actual value and reference value), a comparison is then performed between the actual physical value recorded by the non-destructive testing method and a corresponding physical reference value of the component area 22, which is read from the database and, as mentioned above, contains the aging of the component 2 or its material in at least this test area 22. The comparison is preferably automated, ensuring the greatest possible objectivity.

[0040] In step 150 (evaluation of a deviation), it is then determined whether the deviation lies outside or within the permissible reference value-related tolerance range. The evaluation is preferably automated to ensure the greatest possible objectivity.

[0041] If the deviation lies outside the tolerance range, the aircraft engine is disassembled from the respective aircraft in a step 300 (opening the device), and component 2 is subjected to a destructive materialographic examination in a step 310 (materialographic examination). This means that a conventional inspection of the aircraft engine is carried out, as explained above.

[0042] If the deviation lies within the tolerance range, the test area 22 is preferably subjected to a control test in step 200 (control test with the device closed) to increase safety and reliability (variant 1). Alternatively, step 400 (writing results to database) can be proceeded directly after the positive evaluation (variant 2). Step 400 (writing results to database) is explained below.

[0043] In control test 200 (variant 1), steps 130 (application of a test method with the fixture closed) and 140 (comparison between the actual value and the reference value) are performed again using a non-destructive testing method that differs from the first test method. As with the initial test, the test method for the control test is preferably selected automatically based on criteria such as the component material, component accessibility, and / or previous component history, supplemented by the criterion that the second test method differs from the first test method.

[0044] In step 210 (evaluation of a deviation), which corresponds to step 150 (evaluation of a deviation), at the end of the control test 200 it is determined whether the deviation lies outside or within the permissible tolerance range applicable to the control test.

[0045] If the deviation is outside the tolerance range, the procedure continues with steps 300 (opening the device) and step 310 (materialography examination) explained above.

[0046] If the deviation is within the tolerance range, a step 220 (component "OK") determines that the component material in test area 22 has not been damaged by the overtemperature warning to such an extent that the component should not be used any further. Inspection procedure 1 is then completed for test area 22.

[0047] After performing inspection procedure 1, follow-up processing 1.2 follows (step 400). In step 400 (writing test results to database 105), the actual values ​​obtained from the non-destructive testing and any necessary materialographic examinations are entered into database 105 for further consideration of aging with respect to test area 22.

[0048] In order to make a statement about the material properties of a component section that is not accessible to the borescope or its test head, for example a Figure 1For the base-side component section designated by reference numeral 20, inspection method 1 provides for the condition of the inaccessible component section 20 to be assessed as "OK" if the control test 200 (steps 130, 140 and 210) also shows that the deviation for an accessible test area, in the example test area 22, is within the permissible tolerance range.

[0049] In order to increase the reliability of the inspection method 1, the inspection method 1 is preferably not only carried out for one test area 22, but the inspection method 1 is, as in Figure 2 indicated, applied to a plurality of test areas 22, 24, 26, 28. The inspection procedure 1 can be carried out for each test area 22, 24, 26, 28 in isolation from the other test areas 22, 24, 26, 28 or combined.

[0050] "Isolated" means that the first test procedure is performed at each test area 22, 24, 26, and 28, followed by the control test 200 if the deviation of the first test in the front test area 22 was tolerable. Only then does the test move on to the middle test area 24, then the rear test area 26, and then the suction-side test area 28.

[0051] "Combined" means that the first test procedure is first carried out on all test areas 22, 24, 26, 28 and then, provided that no deviation is outside the respective tolerance field, the control test 200 is carried out on the test areas 22, 24, 26, 28.

[0052] The advantage of the isolated approach is that the borescope essentially does not need to be moved or repositioned for each test area during the initial test and the control test. This ensures that the control test is performed on exactly the same test area (22, 24, 26, 28) as the previous or initial test, increasing the reliability of the measurement results.

[0053] The advantage of the combined approach is that, compared to the isolated approach, the probe does not need to be changed as frequently, since the probe is only changed after the initial test has been completed on all test areas 22, 24, 26, and 28. For this, the borescope, and in particular its probe, must be calibrated twice on each test area.

[0054] Disclosed is a borescope-based inspection method for checking the condition of a component of a device that is not visible from the outside, wherein a structural change in the component material is detected on the basis of a physical property and evaluated in relation to at least one physical reference value that takes into account aging of the material, as well as a system with a computer unit and at least one test head for carrying out such an inspection method for computer-aided and in particular computer-implemented selection of a non-destructive testing method for detecting the physical property and the detection of the physical property itself, carrying out a value comparison between a detected actual value and the reference value and evaluating a tolerance between the actual value and the reference value.

[0055] In the Figures 4a and 4bAn exemplary test head 31 of a system 30 according to the invention is shown. The exemplary test head 31 is particularly suitable for on-wing inspections of engines. This is, as shown in Figure 1shown, is connected to a computer unit 32 via a data line 33. The test head 31 can, in the folded state, be guided, for example, via borescope openings to thermally highly stressed areas such as the leading edge or the center of the gas duct of turbine blades. Its flexible, pincer-shaped design with multiple links 36 allows it to be opened and optimally enclosed around the area of ​​a component 2 to be tested, such as the leading edge of an airfoil, even with different geometries. A main sensor 37, for example, for testing the leading edge of an airfoil, is arranged in the center. This main sensor 37 can be adapted and / or replaced for different engine types or components 2, such as high-pressure turbine blades, if necessary. The lateral links 36 serve to stabilize and fix the test head 31 to the component 2.However, these can also have additional sensors in the form of rigid or movable test buttons 38 in order, for example, to test areas behind the leading edge (internal structure of the blade) on turbine blades via the pressure and suction sides.

[0056] The movable and replaceable probe 31 is mounted on a flexible, rigid, or stiffenable probe guide 34 with integrated signal and / or control lines 33, which connect the probe 31 to the computer unit 32. A pivotable connection device 35 can be provided to connect the probe 31 to the probe guide 34, on which cameras 39 can be mounted for guiding and positioning the probe 31, for performing measurements, and for documenting the examination. List of reference symbols

[0057] 1Inspection procedure 2Component / bucket 4Blade root 6Blade 8Platform 10Suction side 12Pressure side 14Leading edge 16Trailing edge 18Blade-side component section 20Foot-side component section 22Front component area / test area 24Middle component area / test area 26Rear component area / test area 28Suction-side component area / test area 30System 31Test head 32Computer unit 33Data line 34Test head guide 35Connection device 36Links 37Main sensor 38Test button 39Camera 100Creating a database 105Database 110Calibrating test procedures 120Warning message 130Applying the test procedure with the fixture closed 140Comparison between actual value and reference value 150Evaluating a deviation 300Opening the fixture 310 Materialography examination 200 Control test with closed device 210 Evaluation of deviation 220 Component "OK" 400 Writing results to database

Claims

1. On-wing inspection method (1) for quickly examining the condition of blades of an aircraft engine that are not visible from the outside using a borescope, the method comprising the steps of: a. applying a non-destructive testing method (130, 200) in which a physical property of at least one component region (22, 24, 26, 28) is captured, b. carrying out a comparison (140) between a physical actual value captured by the non-destructive testing method (130, 200) and a physical reference value of the component region (22, 24, 26, 28), which is read from a database (105) and in which aging of the component (2) is taken into account, c. evaluating (150, 210) a deviation of the actual value from the reference value.

2. On-wing inspection method according to claim 1, wherein in the testing method (130, 200) the component region (22, 24, 26, 28) is exposed to a microwave field, an ultrasonic field, X-rays or an eddy current, a thermography analysis, vibration and resonance analyses or a conductivity measurement is carried out.

3. On-wing inspection method according to either claim 1 or claim 2, wherein the evaluation (150) comprises determining that the deviation is within a permissible tolerance range, and wherein the component (2) is assessed as being "OK".

4. On-wing inspection method according to either claim 1 or claim 2, wherein the evaluation (150) comprises determining that the deviation is outside a permissible tolerance range, and wherein the component (2) is subjected to a destructive materialographic examination.

5. On-wing inspection method according to either claim 1 or claim 2, wherein the evaluation (150) comprises determining that the deviation is within a permissible tolerance range, and wherein steps a) to c) are repeated at least once with a different non-destructive testing method (200) for the previously tested at least one component region (22, 24, 26, 28).

6. On-wing inspection method according to claim 5, wherein after repeating steps a) to c), the evaluation (210) comprises determining that the deviation is within a permissible tolerance range, and wherein the component (2) is assessed as being "OK".

7. On-wing inspection method according to claim 5, wherein after repeating steps a) to c), the evaluation (210) comprises determining that the deviation is outside a permissible tolerance range, and wherein the device is opened and the component (2) is subjected to a materialographic examination.

8. On-wing inspection method according to claim 6, wherein after repeating steps a) to c), the evaluation (210) comprises determining that the deviation is within a permissible tolerance range, and wherein a component region (22, 24, 26, 28) inaccessible to a probe of the borescope is "OK".

9. On-wing inspection method according to any of the preceding claims, wherein the relevant testing method (130, 200) is calibrated on reference components.

10. System comprising computer unit (32) and probe (31), which is designed to carry out an on-wing inspection method (1) according to any of the preceding claims.

11. System comprising computer unit (32) and probe (31) according to claim 10, wherein the probe (31) has a pincer-shaped design with several members (36), wherein a main sensor (37) is arranged centrally on the probe (31).

12. System comprising computer unit (32) and probe (31) according to claim 11, wherein the lateral members (36) have additional sensors in the form of rigid or movable probes (38).

13. System comprising computer unit (32) and probe (31) according to any of claims 10 to 12, wherein the probe (31) is designed to be movable and exchangeable.

14. System comprising computer unit (32) and probe (31) according to any of claims 10 to 13, wherein the probe (31) is arranged on a flexible, rigid or stiffenable probe guide (34) with integrated signal and / or control lines (33) which connect the probe (31) in particular to the computer unit (32).

15. System comprising computer unit (32) and probe (31) according to claim 14, wherein a pivotable connection device (35) is provided for connecting the probe (31) to the probe guide (34).

16. System comprising computer unit (32) and probe (31) according to claim 15, wherein cameras (39) are provided on the connection device (35).