Flexible cable fire resistance test method and aircraft engine

Abstract

The invention discloses a flexible cable fire resistance test method and an aircraft engine, comprising the following contents: cable electrical connection design, comprising setting a main circuit and an insulation degradation detection circuit, matching the connection relationship between the insulation degradation detection circuit and the cable according to the structure of the cable to be tested, if the cable to be tested does not have a metal shielding net, the main circuit is connected to the first core of the cable to be tested, and the insulation degradation detection circuit is connected to the second core of the cable to be tested, if the cable to be tested has a metal shielding net, the cores of the cable to be tested are bundled and connected to the main circuit, and the insulation degradation detection circuit is connected to the metal shielding net of the cable to be tested; test preparation, comprising cable preparation, setting test conditions and installing the cable to be tested, wherein the test condition setting comprises simulating a combustion environment and simulating working conditions; conducting a fire resistance test on the cable to be tested and detecting the insulation resistance of the cable to be tested in real time through the insulation degradation detection circuit; and testing after the test.

Description

Technical Field

[0001] The present invention relates to the technical field of cable performance testing for aircraft engines, and in particular, to a flexible cable fire resistance test method. In addition, the present invention also relates to an aircraft engine including the flexible cable fire resistance test method. Background Art

[0002] Aircraft engines usually use flexible cables to transmit signals and control commands. As an important component of the engine control system, the fire resistance of the cable in the event of an engine fire is one of the key verification points in the airworthiness requirements of civil aircraft engines. According to relevant regulations: Engine control system components located in designated fire zones must be determined to be fireproof or fire-resistant. Generally, in order to ensure the safety of civil aircraft engines in the event of a fire, the engine cable should maintain the signal transmission function within 5 minutes of the fire, thereby ensuring the control safety of the engine.

[0003] At present, the fire resistance test method for domestic flexible cables is mainly to install the cable on a fire resistance test bench mainly based on a fuel burner by fixing it with a bracket, and then burn it with a flame for 5 minutes. The main criterion for the cable to pass the fire resistance test is that the cable does not spread flames during the test and does not break after the test. For the existing test methods, there is a lack of real-time monitoring of cable performance, and it is impossible to provide monitoring data of cable performance during the 5-minute test. There is a problem of missing test data in terms of test piece performance; the cable is fixedly installed on the fire resistance test bench, which cannot accurately simulate the working environment of the cable's continuous vibration on the aircraft engine. The test conditions for the cable are lacking the necessary conditions, and the test assessment is too loose. Therefore, the existing test methods are no longer sufficient to meet the requirements of verifying the fire resistance of cables and providing support for the safety of aircraft engines. Patent No.: 202310559565.2 discloses a method for testing the insulation resistance of fire-resistant cables under fire conditions. The insulation resistance of the sample during the test is tested by an insulation resistance tester to record in real time and statistically judge the fire resistance performance of the sample. However, its statistics, calculations, and analysis are relatively complex, and involve many influencing parameters. It is difficult, costly, and inefficient to obtain the cable fire resistance performance indicators. Summary of the invention

[0004] The present invention provides a flexible cable fire resistance test method and an aircraft engine to solve the technical problems that the fire resistance test method in the prior art cannot reflect the cable performance in real time during the combustion test when detecting the cable performance at the end of the test, and the fire resistance performance evaluation is difficult and inefficient.

[0005] According to one aspect of the present invention, a flexible cable fire resistance test method is provided, comprising the following contents:

[0006] S1. Cable electrical connection design, including setting up a main circuit and an insulation degradation detection circuit, matching the connection relationship between the insulation degradation detection circuit and the cable according to the structure of the cable to be tested, if the cable to be tested does not have a metal shielding mesh, the main circuit is connected to the first core of the cable to be tested, and the insulation degradation detection circuit is connected to the second core of the cable to be tested, if the cable to be tested has a metal shielding mesh, the cores of the cable to be tested are bundled and connected to the main circuit, and the insulation degradation detection circuit is connected to the metal shielding mesh of the cable to be tested; the main circuit includes a main fuse, a first ammeter, and a first resistor, the first end of the main fuse is connected to the live wire, the second end of the main fuse is connected to the cable to be tested via the first ammeter, and the other end of the cable to be tested is connected to the neutral wire via the first resistor; the insulation degradation detection circuit includes a second resistor, a test switch, a secondary fuse, and a second ammeter; the second end of the main fuse is connected to the cable to be tested via the second resistor and the test switch, and the other end of the cable to be tested is connected to the neutral wire via the secondary fuse and the second ammeter;

[0007] S2. Test preparation, including cable preparation, setting test conditions and installing the cable to be tested. The test condition setting includes simulating the combustion environment and simulating the working conditions;

[0008] S3. Perform a fire resistance test on the cable to be tested and detect the insulation resistance of the cable to be tested in real time through the insulation degradation detection circuit, satisfying the following formula: In the formula, R1 is the resistance value of the first resistor, R2 is the resistance value of the second resistor, R 试验件 is the insulation resistance of the cable to be tested; I1 is the current of the main circuit, I 漏电 is the current of the insulation degradation detection circuit, and U is the voltage applied across the test circuit;

[0009] During the test, the test switch is connected to turn on the insulation degradation detection circuit, and the second current indication value gradually increases from 0. During the test, the second current indication value does not exceed R 试验件 The corresponding leakage current I 漏电 The fire-resistant insulation performance of the cable to be tested meets the requirements;

[0010] S4. Post-test testing;

[0011] When setting the test conditions in step S2, multiple control groups are set based on fixing the first resistance value R1 and adjusting the second resistance value R2. In step S3, the insulation resistance level of the cable to be tested under fire is quantitatively characterized according to the selected resistance value of R2, thereby quantitatively characterizing the fire-resistant insulation performance of the cable to be tested.

[0012] As a further improvement of the above technical solution, step S2 includes:

[0013] S21. Prepare the cable to be tested;

[0014] S22. The middle part of the cable to be tested is used as the test section, and the test section is immersed in the target liquid for a preset time according to the simulated combustion environment, and the target liquid is fuel, lubricating oil or hydraulic oil;

[0015] S23. Install the cable to be tested on the vibration test bench and set the vibration parameters.

[0016] As a further improvement of the above technical solution, the vibration test bench includes a stand, symmetrically distributed mounting buckles arranged on the stand, and a fireproof layer arranged on the mounting buckles. A movable burner is arranged on one side of the vibration test bench. Step S23 includes:

[0017] S231. Pass the cables to be tested through the two mounting buckles and place the test section between the two mounting buckles;

[0018] S232. Tighten the mounting buckle to make the fireproof layer fit the outer wall of the cable to be tested;

[0019] S233. Set vibration parameters and burner operating parameters.

[0020] As a further improvement of the above technical solution, step S233 includes: setting the ejection temperature of the burner to 1093±83°C and the heat flux density ≥105.4kW / m².

[0021] As a further improvement of the above technical solution, step S233 includes: setting the vibration frequency to 30 Hz-60 Hz, the vibration direction to be perpendicular to the axis of the test section, and the vibration acceleration to 4 ,gn=9.80665m / .

[0022] As a further improvement of the above technical solution, step S3 includes:

[0023] S31. Burner calibration before test;

[0024] S32. Move the burner along the installation direction of the test section of the cable to be tested, conduct a fire test for a preset time and detect in real time;

[0025] S33. Remove the burner and perform post-test burner calibration.

[0026] As a further improvement of the above technical solution, the test method includes:

[0027] Check whether the cable has a circuit break fault. If the first current indication number is 0, the cable under test has a circuit break fault. If the first current indication number is not 0, the cable under test does not have a circuit break fault. Check whether there is residual fire in the test section and observe whether the test section of the cable under test continues to burn.

[0028] According to another aspect of the present invention, there is also provided an aircraft engine, which includes the above-mentioned flexible cable fire resistance test method.

[0029] The present invention has the following beneficial effects:

[0030] This test method uses the insulation resistance of the flexible cable as a monitoring parameter to design an insulation degradation detection circuit, and uses the insulation degradation detection circuit to measure the insulation resistance of the cable to reflect the degree of degradation of the cable insulation layer in real time during the test as an indicator to characterize the degree of cable leakage. On the other hand, the flexible cables used in civil engines are mostly multi-core cables. This test method matches the connection relationship of the insulation degradation detection circuit based on the design characteristics of the flexible cable. If the cable to be tested does not have a metal shielding mesh, the test is carried out based on the core-to-core insulation. The main circuit is connected to one core of the cable to be tested, and the insulation degradation detection circuit is connected to the other core of the cable to be tested. The circuit is isolated by using the structure between the cores, and the insulation degradation detection circuit is used to characterize the insulation performance between the two harnesses. If the cable to be tested has a metal shielding mesh, the test is carried out based on the core-to-metal shielding mesh insulation. The main circuit is connected to all the cores of the cable to be tested after bundling, and the insulation degradation detection circuit is connected to a conductive metal shielding mesh. The insulation between the core and the external structure of the cable is used to achieve circuit isolation, and the insulation between the core and the metal shielding mesh of the cable is characterized by the measurement results of the insulation degradation detection circuit. Insulation performance; Based on the design of the detection circuit, in the test, by fixing the resistance value of the first resistor and selecting multiple groups of second resistance values ​​in a step distribution as the control group for testing, when the first resistance remains unchanged, the smaller the value of the second resistance is, the stronger the fire resistance of the cable is. Since the circuit is open before and during the test according to whether the first current representation number is 0, and whether the insulation resistance meets the requirements can be judged according to whether the second current representation number exceeds the corresponding leakage current value, based on this, the fire-resistant insulation resistance of the cable to be tested can be quantitatively characterized directly according to whether each control group passes the test, and then the fire-resistant insulation capacity of the cable to be tested is quantitatively characterized, and the fire-resistant insulation performance index level can be divided according to the selection of the second resistance value, without relying on a large amount of data statistical analysis, which greatly improves the test efficiency; This test method realizes real-time monitoring of the cable performance during the test through the cable electrical connection design, and simulates the actual working conditions and combustion environment to set the test conditions in the test, effectively simulating the actual working environment of the cable applied to the aircraft engine, effectively improving the accuracy and reference value of the cable test results, and improving the safety performance of the aircraft engine.

[0031] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0033] Figure 1 is a circuit diagram of a core-to-core insulation solution of a preferred embodiment of the present invention;

[0034] Figure 2 It is a circuit diagram of the wire core to metal shielding mesh insulation scheme of the preferred embodiment of the present invention;

[0035] Figure 3 is a reference diagram of the use state of the vibration test bench of the preferred embodiment of the present invention;

[0036] Figure 4 It is a flow chart of the test method of the preferred embodiment of the present invention.

[0037] Legend:

[0038] 101, main fuse; 102, first ammeter; 103, cable to be tested; 104, auxiliary fuse; 105, second ammeter; 106, test section; K, test switch; R1, first resistor; R2, second resistor; 201, stand; 202, mounting buckle; 203, fireproof layer. DETAILED DESCRIPTION

[0039] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0040] Figure 1 is a circuit diagram of a core-to-core insulation solution of a preferred embodiment of the present invention; Figure 2 It is a circuit diagram of the wire core to metal shielding mesh insulation scheme of the preferred embodiment of the present invention; Figure 3 is a reference diagram of the use state of the vibration test bench of the preferred embodiment of the present invention; Figure 4 It is a flow chart of the test method of the preferred embodiment of the present invention.

[0041] like Figures 1 to 4 As shown, the flexible cable fire resistance test method of this embodiment includes the following contents:

[0042] S1. Cable electrical connection design, including setting up a main circuit and an insulation degradation detection circuit, matching the connection relationship between the insulation degradation detection circuit and the cable according to the structure of the cable to be tested, if the cable to be tested does not have a metal shielding mesh, the main circuit is connected to the first core of the cable to be tested, and the insulation degradation detection circuit is connected to the second core of the cable to be tested, if the cable to be tested has a metal shielding mesh, the cores of the cable to be tested are bundled and connected to the main circuit, and the insulation degradation detection circuit is connected to the metal shielding mesh of the cable to be tested; the main circuit includes a main fuse, a first ammeter, and a first resistor, the first end of the main fuse is connected to the live wire, the second end of the main fuse is connected to the cable to be tested via the first ammeter, and the other end of the cable to be tested is connected to the neutral wire via the first resistor; the insulation degradation detection circuit includes a second resistor, a test switch, a secondary fuse, and a second ammeter; the second end of the main fuse is connected to the cable to be tested via the second resistor and the test switch, and the other end of the cable to be tested is connected to the neutral wire via the secondary fuse and the second ammeter;

[0043] S2. Test preparation, including cable preparation, setting test conditions and installing the cable to be tested. The test condition setting includes simulating the combustion environment and simulating the working conditions;

[0044] S3. Perform a fire resistance test on the cable to be tested and detect the insulation resistance of the cable to be tested in real time through the insulation degradation detection circuit, satisfying the following formula:

[0045] In the formula, R1 is the resistance value of the first resistor, R2 is the resistance value of the second resistor, R 试验件 is the insulation resistance of the cable to be tested; I1 is the current of the main circuit, I 漏电 is the current of the insulation degradation detection circuit, and U is the voltage applied across the test circuit;

[0046] During the test, the test switch is connected to turn on the insulation degradation detection circuit, and the second current indication value gradually increases from 0. During the test, the second current indication value does not exceed R 试验件 The corresponding leakage current I 漏电 The fire-resistant insulation performance of the cable to be tested meets the requirements;

[0047] S4. Post-test testing;

[0048] When setting the test conditions in step S2, multiple control groups are set based on fixing the first resistance value R1 and adjusting the second resistance value R2. In step S3, the insulation resistance level of the cable to be tested under fire is quantitatively characterized according to the selected resistance value of R2, thereby quantitatively characterizing the fire-resistant insulation performance of the cable to be tested.

[0049] The first core is any core of the cable to be tested, and the second core is any core other than the first core of the cable to be tested;

[0050] It is understandable that in a fire situation, the impact of flames on cable performance is mainly manifested as leakage and power outages. The main cause of the impact is the degradation of the cable insulation layer. This test method uses the insulation resistance of the flexible cable as a monitoring parameter to design an insulation degradation detection circuit. The insulation resistance of the cable is measured using the insulation degradation detection circuit to reflect the degree of degradation of the cable insulation layer in real time during the test as an indicator of the degree of cable leakage. On the other hand, the flexible cables used in civil engines are mostly multi-core cables. This test method is based on the design characteristics of the flexible cable to match the connection relationship of the insulation degradation detection circuit. If The cable to be tested does not have a metal shielding mesh. The test is carried out based on the core-to-core insulation. The main circuit is connected to one core of the cable to be tested, and the insulation degradation detection circuit is connected to the other core of the cable to be tested. The circuit isolation is achieved by using the structure between the cores. The insulation degradation detection circuit is used to characterize the insulation performance between the two harnesses. If the cable to be tested has a metal shielding mesh, the test is carried out based on the core-to-metal shielding mesh insulation. The main circuit is connected to all the cores of the cable to be tested after being bundled, and the insulation degradation detection circuit is connected to the conductive metal shielding mesh. The circuit isolation is achieved by using the insulation between the core and the external structure of the cable, and the insulation degradation detection circuit is tested by The measurement result of the insulation degradation detection circuit characterizes the insulation performance between the wire core and the metal shielding net of the cable; based on the design of this detection circuit, in the test, by fixing the resistance value of the first resistor and selecting multiple groups of second resistance values ​​in a step distribution as the control group for testing, when the first resistance remains unchanged, the smaller the value of the second resistance is, the stronger the fire resistance of the cable is. Since the circuit is open before and during the test according to whether the first current representation number is 0, and whether the insulation resistance meets the requirements according to whether the second current representation number exceeds the corresponding leakage current value, it can be judged. Based on this, the fire-resistant insulation resistance of the cable to be tested can be quantitatively characterized directly according to whether each control group passes the test, and then the fire-resistant insulation capacity of the cable to be tested is quantitatively characterized, and the fire-resistant insulation performance index level can be divided according to the selection of the second resistance value, without relying on a large amount of data statistical analysis, which greatly improves the test efficiency; this test method realizes real-time monitoring of the cable performance during the test through the cable electrical connection design, and simulates the actual working conditions and combustion environment to set the test conditions in the test, effectively simulating the actual working environment of the cable applied to the aircraft engine, effectively improving the accuracy and reference value of the cable test results, and improving the safety performance of the aircraft engine.

[0051] In this embodiment, step S2 includes:

[0052] S21. Prepare the cable to be tested;

[0053] Specifically, a plurality of cables to be tested are prepared before the test. The cable length in this embodiment is preferably set to 750 mm, but is not limited in other embodiments.

[0054] S22. The middle part of the cable to be tested is used as the test section. The test section is immersed in the target liquid for a preset time according to the simulated combustion environment. The target liquid is fuel, lubricating oil or hydraulic oil. The length of the test section in this preferred embodiment is about 500mm in the middle of the cable. The immersion time is preferably 24h or more to ensure that the test section is fully soaked and closer to the actual use environment state. It should be noted that the test section of each cable is immersed in only one target liquid, that is, to simulate its liquid contact state in a matching working environment.

[0055] S23. Install the cable to be tested on the vibration test bench and set the vibration parameters;

[0056] Specifically, the vibration test bench includes a stand 201, symmetrically distributed mounting buckles 202 arranged on the stand 201, and a fireproof layer 203 arranged on the inner wall of the mounting buckle 202, wherein the fireproof layer 203 is preferably a fireproof cotton with a certain length, and a movable burner is arranged on one side of the vibration test bench. Step S23 includes:

[0057] S231. Pass the cables to be tested through the two mounting buckles and place the test section between the two mounting buckles;

[0058] S232. Tighten the mounting buckle to make the fireproof layer fit the outer wall of the cable to be tested;

[0059] S233. Set vibration parameters and burner operating parameters.

[0060] Among them, step S233 includes: setting the burner's ejection temperature to 1093±83°C, the heat flux density ≥105.4kW / m², and the heat flux density parameter can also be changed to a heat flow of not less than 1320W (4500Btu / h) measured by the copper tube water flow method.

[0061] Step S233 includes: setting the vibration frequency to 30 Hz-60 Hz, the vibration direction to be perpendicular to the axis of the test section, and the vibration acceleration to 4 (gn=9.80665m / ), the vibration is applied to the cable through the vibration test bench, effectively simulating the working state of the aircraft engine.

[0062] In this embodiment, step S3 includes:

[0063] S31. Before the test, the burner is calibrated and the main circuit is energized;

[0064] S32. Move the burner along the installation direction of the test section of the cable to be tested, conduct a fire test for a preset time and detect in real time;

[0065] The fire resistance test duration is usually 5 minutes, which means that the cable can maintain the signal transmission function within 5 minutes in the event of a fire, ensuring the safety of engine control.

[0066] S33. Remove the burner and perform post-test burner calibration.

[0067] In this embodiment, the test method includes:

[0068] Check whether the cable has a circuit breakage fault. Before the test starts, the first current indication number is not 0, which indicates that the cable to be tested does not have a circuit breakage fault. If the indication is 0, the cable to be tested has a circuit breakage fault. During the test, the first current indication number of the main circuit is 0, and the indication before the test is checked to check whether the cable has a circuit breakage fault. Check whether there is residual fire in the test section, and observe whether the test section of the cable to be tested continues to burn, that is, after the test is completed, there should be no circuit breakage fault and no residual fire at both ends of the cable. It should be noted that after the burner is removed, if the test section quickly and automatically extinguishes and does not reignite, it is within an acceptable range.

[0069] In one embodiment, a 2A current is connected to the cable under test, the resistance value of R1 is 62.5Ω, the resistance value of R2 is 5kΩ, the main fuse is 5A, the auxiliary fuse is 50mA, the second ammeter is a milliammeter, and during the fire resistance test, the second ammeter should read 25mA.

[0070] This test method is based on setting up an insulation degradation detection circuit to achieve real-time monitoring of the fire resistance test of flexible cables for aircraft engines, and determines the test pass criteria, namely, the indication of the second ammeter of the insulation degradation detection circuit during the test should satisfy the above formula; there is no short circuit fault at both ends of the cable after the test; there is no residual fire after the test; the accuracy and reference of the test results are guaranteed, and vibration loads are reliably applied to the cables by liquid infiltration of the cables, designing cable installation and fixing the vibration test bench, effectively simulating the real working environment on the aircraft engine.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A flexible cable fire resistance test method, characterized in that: Includes the following: S1. Cable electrical connection design, including setting up a main circuit and an insulation degradation detection circuit, matching the connection relationship between the insulation degradation detection circuit and the cable according to the structure of the cable to be tested, if the cable to be tested does not have a metal shielding mesh, the main circuit is connected to the first core of the cable to be tested, and the insulation degradation detection circuit is connected to the second core of the cable to be tested, if the cable to be tested has a metal shielding mesh, the cores of the cable to be tested are bundled and connected to the main circuit, and the insulation degradation detection circuit is connected to the metal shielding mesh of the cable to be tested; the main circuit includes a main fuse, a first ammeter, and a first resistor, the first end of the main fuse is connected to the live wire, the second end of the main fuse is connected to the cable to be tested via the first ammeter, and the other end of the cable to be tested is connected to the neutral wire via the first resistor; the insulation degradation detection circuit includes a second resistor, a test switch, a secondary fuse, and a second ammeter; the second end of the main fuse is connected to the cable to be tested via the second resistor and the test switch, and the other end of the cable to be tested is connected to the neutral wire via the secondary fuse and the second ammeter; S2. Test preparation, including cable preparation, setting test conditions and installing the cable to be tested. The test condition setting includes simulating the combustion environment and simulating the working conditions; S3. Carry out fire resistance test on the cable to be tested and detect the insulation resistance of the cable to be tested in real time through the insulation degradation detection circuit. During the test, the test switch is connected to turn on the insulation degradation detection circuit, and the second current indication number gradually increases from 0. If the second current indication number does not exceed the leakage current threshold corresponding to the insulation resistance of the cable to be tested, the fire-resistant insulation performance of the cable to be tested meets the requirements; S4. Post-test testing; When setting the test conditions in step S2, multiple control groups are set based on fixing the resistance value of the first resistor and adjusting the resistance value of the second resistor. In step S3, the insulation resistance level of the cable to be tested under fire is quantitatively characterized according to the resistance value of the selected second resistor, thereby quantitatively characterizing the fire-resistant insulation performance of the cable to be tested.

2. The flexible cable fire resistance test method according to claim 1, characterized in that: Step S2 includes: S21. Prepare the cable to be tested; S22. The middle part of the cable to be tested is used as the test section, and the test section is immersed in the target liquid for a preset time according to the simulated combustion environment, and the target liquid is fuel, lubricating oil or hydraulic oil; S23. Install the cable to be tested on the vibration test bench and set the vibration parameters.

3. The flexible cable fire resistance test method according to claim 2, characterized in that: The vibration test bench includes a frame, symmetrically distributed mounting buckles arranged on the frame, and a fireproof layer arranged on the mounting buckles. A movable burner is arranged on one side of the vibration test bench. Step S23 includes: S231. Pass the cables to be tested through the two mounting buckles and place the test section between the two mounting buckles; S232. Tighten the mounting buckle to make the fireproof layer fit the outer wall of the cable to be tested; S233. Set vibration parameters and burner operating parameters.

4. The flexible cable fire resistance test method according to claim 3, characterized in that: Step S233 includes: setting the burner's ejection temperature to 1093±83°C and the heat flux density to ≥105.4kW / m².

5. The flexible cable fire resistance test method according to claim 3, characterized in that: Step S233 includes: setting the vibration frequency to 30 Hz-60 Hz, the vibration direction to be perpendicular to the axis of the test section, and the vibration acceleration to 4 g. n , g n =9.80665m / s 2 .

6. The flexible cable fire resistance test method according to claim 3, characterized in that: Step S3 includes: S31. Before the test, the burner is calibrated and the main circuit is energized; S32. Move the burner along the installation direction of the test section of the cable to be tested, conduct a fire test for a preset time and detect in real time; S33. Remove the burner and perform post-test burner calibration.

7. The flexible cable fire resistance test method according to claim 6, characterized in that: Step S31 includes: Detect whether the cable has a circuit break fault. If the first current indication number is 0, the cable under test has a circuit break fault. If the first current indication number is not 0, the cable under test does not have a circuit break fault. Step S33 includes: Check whether there is any residual fire in the test section and observe whether the test section of the cable under test continues to burn.

8. An aircraft engine, characterized in that: The flexible cable fire resistance test method according to any one of claims 1 to 7 is applied.

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