An equivalent alternative verification method for aircraft system-level high-intensity radiation field protection

Abstract

The present invention provides an aircraft system-level high-intensity radiation field protection equivalent substitution verification method, S1. When the induced current I of the test equipment harness in the low-level scanning current test of the whole aircraft HIRF test is LLSC ( f ), which is higher than the upper limit of the level of the interference current injected in the system-level HIRF protection conducted sensitivity test I CS_MAX ( f ), the shielding effectiveness S when the cable type of the tested equipment harness is a harness with a wave-proof sleeve or a shielded wire X ( f ); S2. Based on I LLSC ( f ), S X ( f ) Calculate the induced current I of the wiring harness of the equipment under test after removing the anti-wave sleeve or changing to unshielded wire LLSC_X ( f ); S3. with I LLSC_X ( f ) as the test level for conducting a system-level HIRF protection conducted susceptibility test after removing the shielding sleeve or replacing it with unshielded cables. Passing the test demonstrates the compliance of the aircraft system's HIRF protection. This invention solves the problem of verifying the compliance of HIRF protection for aircraft systems, particularly flight control systems.

Description

Technical Field

[0001] The present invention relates to the field of high-intensity radiation field (HIRF) protection testing of aircraft systems, and in particular to an aircraft system-level HIRF protection equivalent substitution verification method. Background Art

[0002] High-intensity radiated fields (HIRF) refer to the electromagnetic environment created by radiation from high-power transmitters such as radar, radio, navigation, and broadcast television on the ground, ships, offshore platforms, or aircraft. Its key characteristics are: 1) a wide frequency band, encompassing all operating frequencies for broadcasting, radio communications, navigation, and radar, ranging from 10 kHz to tens of GHz; 2) high peak values; the maximum field strength in a HIRF environment specified in civil aviation airworthiness regulations can reach 3000 V / m; and 3) a long duration. Compared to transient lightning, HIRF lasts longer, especially during takeoff, landing, and low-altitude flight, when aircraft are within visual range of high-power transmitters on the ground, exposing them to harsh HIRF environments for extended periods of time.

[0003] The inherent characteristics of high-frequency interference (HIRF) expose aircraft electronic and electrical equipment to potential electromagnetic damage, primarily due to interference coupling between strong external electromagnetic fields and the equipment. Electromagnetic energy from the external HIRF environment enters the aircraft through apertures such as windshields, windows, and doors, or through composite airframe structures, generating induced electromagnetic fields within the cabin. These induced electromagnetic fields can couple into the electronic equipment chassis through apertures, radiating interference to internal modules, board-level circuits, and components. Furthermore, through field line coupling, they induce currents in interconnecting cables, disrupting internal circuits. When radiated or conducted interference exceeds the sensitivity thresholds of the equipment and components, the electronic and electrical equipment can experience performance degradation, malfunction, and even, in severe cases, damage or burnout. These symptoms can include unstable control systems, malfunctioning control surfaces, sudden engine speed changes, interference with radio communications, and incorrect display of navigation parameters such as heading and altitude. In severe cases of HIRF interference, aircraft loss of control and crashes are possible.

[0004] To this end, civil aircraft airworthiness standards set clear requirements for aircraft system HIRF protection. To ensure compliance with aircraft system HIRF protection, aircraft-level and system-level HIRF protection testing must be conducted in accordance with relevant standards. The purpose of aircraft-level HIRF testing is to extrapolate the internal RF environmental level (based on frequency, divided into induced current on the wiring harness and internal electric field strength) corresponding to an external HIRF environment, using aircraft low-level coupling testing. The purpose of system-level HIRF protection testing is to confirm the HIRF sensitivity level that the system can withstand based on the aircraft-level HIRF test results. The aircraft-level HIRF test results must not exceed the system-level HIRF protection test results; otherwise, compliance with the aircraft system HIRF protection cannot be demonstrated.

[0005] Due to the presence of electromagnetic openings in the active flight control surfaces such as the aircraft wings, horizontal tail, and vertical tail, electromagnetic waves enter the control surface structure cavity with electromagnetic openings under external HIRF irradiation, resulting in multiple reflections and increased field strength. This will generate conducted interference currents (e.g., levels up to 1A or above) on the flight control system cables that are far higher than the test capability of the system-level HIRF protection laboratory (e.g., the upper limit of the injection current level is 300mA). Therefore, an equivalent alternative method for the aircraft system-level HIRF protection test must be considered; otherwise, the compliance verification work for the aircraft system HIRF protection cannot be continued. Summary of the Invention

[0006] The purpose of the present invention is to provide an aircraft system-level high-intensity radiation field protection equivalent substitution verification method, which solves the HIRF protection compliance verification problem of aircraft systems, especially flight control systems.

[0007] Technical solution: A method for verifying equivalent substitution of aircraft system-level high-intensity radiation field protection, including:

[0008] S1. When the low level scanning current test of the whole machine HIRF test is in the test equipment harness, the induced current I LLSC ( f ), which is higher than the upper limit of the level of the interference current injected in the system-level HIRF protection conducted sensitivity test I CS_MAX ( f ), the shielding effectiveness S when the cable type of the tested equipment harness is a harness with a wave-proof sleeve or a shielded wire X ( f );

[0009] S2. Based on I LLSC ( f ), S X ( f ) Calculate the induced current I of the wiring harness of the equipment under test after removing the anti-wave sleeve or changing to unshielded wire LLSC_X ( f );

[0010] S3. With I LLSC_X ( f ) is used as the test level to conduct a system-level HIRF protection conducted sensitivity test after removing the anti-wave sleeve or changing to an unshielded line. Passing the test can indicate the compliance of the aircraft system HIRF protection.

[0011] In the above-mentioned aircraft system-level high-intensity radiation field protection equivalent alternative verification method S1, when I LLSC ( f )≤I CS_MAX ( f ), there is no need to consider the system-level HIRF protection equivalent alternative test.

[0012] In S1 of the aforementioned aircraft system-level high-intensity radiation field protection equivalent alternative verification method, when the cable type of the test equipment harness is unshielded wire, the HIRF protection design of the test equipment harness is rectified, and then S1 is re-executed.

[0013] In the aforementioned aircraft system-level high-intensity radiation field protection equivalent alternative verification method S1, I LLSC ( f ) is: the induced current on the test equipment wiring harness obtained by extrapolation when the outside of the aircraft is in the certified HIRF environment or the general HIRF environment, based on the low-level sweep current test results in the full-aircraft HIRF test; among which, the low-level sweep current test results in the full-aircraft HIRF test are: the transfer function of the test equipment wiring harness.

[0014] In the aforementioned aircraft system-level high-intensity radiation field protection equivalent alternative verification method S1, I CS_MAX ( f ) is obtained based on the level corresponding to Category O in Chapter 20 of the RF Susceptibility Test (Conduction) in the RTCA DO-160G standard.

[0015] In the above-mentioned aircraft system-level high-intensity radiation field protection equivalent alternative verification method, when the cable type of the test equipment harness in S1 is a harness with a wave-proof sleeve, the tested shielding effectiveness S X ( f ) is the shielding effectiveness S of the wave-proof sleeve H ( f ), at this time the induced current I in S2 LLSC_X ( f ) is: the induced current I of the wiring harness of the tested equipment after removing the anti-wave cover LLSC_H ( f ), I LLSC_H ( f ) is calculated as follows:

[0016] I LLSC_H ( f ) = I LLSC ( f ) / S H ( f ).

[0017] In the above-mentioned aircraft system-level high-intensity radiation field protection equivalent alternative verification method, when the cable type of the test equipment harness in S1 is shielded wire, the tested shielding effectiveness S X ( f ) is the shielding effectiveness S of the shielded wire W ( f ), at this time the induced current I in S2 LLSC_X ( f) is: the induced current I of the harness of the tested equipment after changing to unshielded wire LLSC_W ( f ), I LLSC_W ( f ) is calculated as follows:

[0018] I LLSC_W ( f ) = I LLSC ( f ) / S W ( f ).

[0019] In S3 of the aforementioned aircraft system-level high-intensity radiation field protection equivalent alternative verification method, after removing the anti-wave cover of the test equipment harness or changing it to an unshielded wire, the system-level HIRF protection conducted sensitivity test is carried out, using the conducted sensitivity test method of Chapter 20 of the RTCA DO-160G standard for radio frequency sensitivity test.

[0020] Beneficial Effects: Due to electromagnetic openings in aircraft structures such as wings, horizontal tails, and vertical tails, external HIRF electromagnetic energy entering the aircraft's structural cavities with electromagnetic openings can be reflected multiple times, increasing the electric field strength. This can generate interference currents in system cables that far exceed the system-level HIRF protection conducted susceptibility test capability, making it impossible to complete the aircraft system HIRF protection compliance verification. The aircraft system-level HIRF protection equivalent substitution verification method provided by the present invention can resolve this problem in aircraft system-level HIRF protection conducted susceptibility testing, effectively support aircraft system HIRF protection compliance verification, and have a positive impact and value on aircraft type airworthiness certification. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is an embodiment of the equivalent alternative verification steps for aircraft system-level high-intensity radiation field protection;

[0022] Figure 2 This is the induced current test curve on the actuator wiring harness in the aileron of a certain aircraft flight control system;

[0023] Figure 3 This is a photo of the on-site arrangement for testing the shielding effectiveness of the anti-wave shielding sleeve of the wiring harness of a certain model of aileron internal actuator. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0025] Example 1. An aircraft system-level HIRF protection equivalent alternative verification method, see Figure 1 The main steps are as follows:

[0026] Step 1: Conduct a low-level sweep current (LLSC) test of the full-machine high-intensity radiated field (HIRF) test to obtain the induced current I of the wiring harness of the equipment under test. LLSC ( f );

[0027] Step 2: Determine the induced current I of the wiring harness of the tested equipment LLSC ( f ) is higher than the upper limit value of the level of the interference current injected in the system-level HIRF protection conducted sensitivity test I CS_MAX ( f ), if the result is no, there is no need to consider the system-level HIRF protection equivalent alternative test; if the result is yes, proceed to step 3;

[0028] Step 3. Confirm the cable type of the test equipment harness, such as surge protector, shielded wire, unshielded wire, etc.

[0029] Step 4: Determine whether the wiring harness of the device under test has a surge protector. If the result is no, proceed to step 5; if the result is yes, proceed to step 6.

[0030] Step 5: Determine whether the cables in the harness of the device under test are shielded cables. If not, perform HIRF protection design corrections on the harness of the device under test and restart step 1. If yes, proceed to step 7.

[0031] Step 6: Use the method described in the invention patent "A shielding attenuation measurement method and device for aircraft wiring harness anti-wave sleeve" (ZL201910968003.7) to test the shielding effectiveness of the anti-wave sleeve and obtain the shielding effectiveness S of the anti-wave sleeve. H ( f ), based on the low-level scan current (LLSC) test results of step 1 I LLSC ( f ) and wave shielding effectiveness test results S H ( f ), calculate the induced current I of the harness of the tested equipment after removing the anti-wave cover LLSC_H ( f ) = I LLSC ( f ) / S H ( f );

[0032] Step 7: Use the triaxial method to test the shielding effectiveness of the shielded cable and obtain the shielding effectiveness S of the shielded cable. W ( f ), based on the low-level scan current (LLSC) test results of step 1 I LLSC ( f ) and shielding effectiveness test results S W (f ), calculate the induced current I of the harness of the tested equipment after it is changed to a non-shielded wire LLSC_W ( f ) = I LLSC ( f ) / S W ( f );

[0033] Step 8: For the wiring harness of the tested equipment with the anti-wave cover removed or changed to non-shielded wire, the induced current I LLSC_H ( f ) or I LLSC_W ( f ) as the test level for system-level HIRF protection conducted susceptibility testing;

[0034] Step 9: Determine whether the system-level HIRF protection conducted sensitivity test of the equipment under test has passed. If not, proceed to step 10. If yes, the aircraft system HIRF protection conforms to the test.

[0035] Step 10: Make HIRF protection design corrections for the aircraft structure or the equipment under test and restart Step 1.

[0036] Example 2. Figure 1 As shown, the present invention provides an aircraft system-level HIRF protection equivalent substitution verification method, which is used to solve the problem of being unable to complete aircraft system HIRF protection compliance verification due to interference current generated on system cables that far exceeds the system-level conducted susceptibility test capability, thereby effectively supporting aircraft system HIRF protection compliance verification. The aircraft system-level HIRF protection equivalent substitution verification method specifically includes the following steps:

[0037] Step 1: Conduct a low-level sweep current (LLSC) test of the full-machine high-intensity radiated field (HIRF) test to obtain the induced current I of the wiring harness of the equipment under test. LLSC ( f );

[0038] Step 2: Determine the induced current I of the wiring harness of the tested equipment LLSC ( f ) is higher than the upper limit value of the level of the interference current injected in the system-level HIRF protection conducted sensitivity test I CS_MAX ( f ), the upper limit of the level refers to the level corresponding to Category O of Chapter 20 of the RF Susceptibility Test (Conduction) in the RTCA DO-160G standard. If the judgment result is no, there is no need to consider the system-level HIRF protection equivalent alternative test; if the judgment result is yes, proceed to step 3;

[0039] Step 3. Confirm the cable type of the test equipment harness, such as surge protector, shielded wire, unshielded wire, etc.

[0040] Step 4: Determine whether the wiring harness of the device under test has a surge protector. If the result is no, proceed to step 5; if the result is yes, proceed to step 6.

[0041] Step 5: Determine whether the cables in the harness of the device under test are shielded cables. If not, perform HIRF protection design corrections on the harness of the device under test and restart step 1. If yes, proceed to step 7.

[0042] Step 6: Use the method described in the invention patent "A shielding attenuation measurement method and device for aircraft wiring harness anti-wave sleeve" (ZL201910968003.7) to test the shielding effectiveness of the anti-wave sleeve and obtain the shielding effectiveness S of the anti-wave sleeve. H ( f ), based on the low-level scan current (LLSC) test results of step 1 I LLSC ( f ) and wave shielding effectiveness test results S H ( f ), calculate the induced current I of the harness of the tested equipment after removing the anti-wave cover LLSC_H ( f ) = I LLSC ( f ) / S H ( f );

[0043] Step 7: Use the triaxial method to test the shielding effectiveness of the shielded cable and obtain the shielding effectiveness S of the shielded cable. W ( f ), based on the low-level scan current (LLSC) test results of step 1 I LLSC ( f ) and shielding effectiveness test results S W ( f ), calculate the induced current I of the harness of the tested equipment after it is changed to a non-shielded wire LLSC_W ( f ) = I LLSC ( f ) / S W ( f );

[0044] Step 8: For the wiring harness of the tested equipment with the anti-wave cover removed or changed to non-shielded wire, the induced current I LLSC_H ( f ) or I LLSC_W ( f) as the test level for system-level HIRF protection conducted susceptibility testing;

[0045] Step 9: Determine whether the system-level HIRF protection conducted sensitivity test of the equipment under test has passed. If not, proceed to step 10. If yes, the aircraft system HIRF protection conforms to the test.

[0046] Step 10: Make HIRF protection design corrections for the aircraft structure or the equipment under test and restart Step 1.

[0047] Example 3. The aircraft system-level HIRF protection equivalent substitution verification method adopted in this example is specifically as follows:

[0048] Step 1: Conduct a low-level sweep current test of the high-intensity radiated field (HIRF) test on a certain aircraft model to obtain the induced current I on the actuator harness in the aileron of the flight control system. LLSC ( f ),like Figure 2 As shown, the blue line is the induced current curve when the aircraft's external HIRF environment is the certified HIRF environment, the green line is the induced current curve when the aircraft's external HIRF environment is the general HIRF environment, and the red line is the level limit curve for the system-level HIRF protection conducted susceptibility test.

[0049] Step 2: Determine the induced current I of the aileron actuator harness LLSC ( f ) is higher than the upper limit value of the level of the interference current injected in the system-level HIRF protection conducted sensitivity test I CS_MAX ( f ), the upper limit of the level refers to the level corresponding to Category O of Chapter 20 RF Susceptibility Test (Conduction) in the RTCA DO-160G standard. In some frequency ranges, I LLSC ( f )>I CS_MAX ( f ), the judgment result is yes;

[0050] Step 3. Confirm the cable type of the aileron actuator harness, such as wave-proof sleeve, shielded wire, unshielded wire, etc.

[0051] Step 4: Determine whether the aileron actuator harness has a wave-proof cover. The judgment result is yes.

[0052] Step 5: Use the method described in the invention patent "A method and device for measuring shielding attenuation of aircraft wiring harness anti-wave sleeve" (ZL201910968003.7) to carry out the shielding effectiveness test of the anti-wave sleeve, such as Figure 3 As shown, the shielding effectiveness S of the wave-proof sleeve is obtained H ( f), based on the low-level scan current (LLSC) test results of step 1 I LLSC ( f ) and wave shielding effectiveness test results S H ( f ), calculate the induced current I of the aileron actuator harness after removing the anti-wave cover LLSC_H ( f ) = I LLSC ( f ) / S H ( f );

[0053] Step 6: Remove the aileron actuator wiring harness after the anti-wave cover is removed to determine the wiring harness induced current I LLSC_H ( f ) as the test level for system-level HIRF protection conducted susceptibility testing;

[0054] Step 7: Determine whether the aileron internal actuator system-level HIRF protection conducted sensitivity test has passed. A positive result indicates compliance with the HIRF protection of the flight control system of a certain aircraft model.

Claims

1. A method for verifying equivalent substitution of high-intensity radiation field protection at the aircraft system level, characterized in that: include: S1. When the low level scanning current test of the whole machine HIRF test is in the test equipment harness, the induced current I LLSC ( f ), which is higher than the upper limit of the level of the interference current injected in the system-level HIRF protection conducted sensitivity test I CS_MAX ( f ), the shielding effectiveness S when the cable type of the tested equipment harness is a harness with a wave-proof sleeve or a shielded wire X ( f ); S2. Based on I LLSC ( f ), S X ( f ) Calculate the induced current I of the wiring harness of the equipment under test after removing the anti-wave sleeve or changing to unshielded wire LLSC_X ( f ); S3. With I LLSC_X ( f ) is used as the test level to conduct a system-level HIRF protection conducted sensitivity test after removing the anti-wave sleeve or changing to an unshielded line. Passing the test can indicate the compliance of the aircraft system HIRF protection.

2. The aircraft system-level high-intensity radiation field protection equivalent substitution verification method according to claim 1 is characterized in that: In S1, when I LLSC ( f )≤I CS_MAX ( f ), there is no need to consider the system-level HIRF protection equivalent alternative test.

3. The aircraft system-level high-intensity radiation field protection equivalent substitution verification method according to claim 1 is characterized in that: In S1, if the cable type of the test equipment harness is unshielded, perform HIRF protection design rectification on the test equipment harness, and then re-execute S1.

4. The aircraft system-level high-intensity radiation field protection equivalent substitution verification method according to claim 1 is characterized in that: When the cable type of the tested equipment harness in S1 is a harness with a wave-proof sleeve, the shielding effectiveness S X ( f ) is the shielding effectiveness S of the wave-proof sleeve H ( f ), at this time the induced current I in S2 LLSC_X ( f ) is: the induced current I of the wiring harness of the tested equipment after removing the anti-wave cover LLSC_H ( f ), I LLSC_H ( f ) is calculated as follows: I LLSC_H ( f )= I LLSC ( f ) / S H ( f )。 5. The aircraft system-level high-intensity radiation field protection equivalent substitution verification method according to claim 1 is characterized in that: When the cable type of the tested equipment harness in S1 is shielded wire, the shielding effectiveness S X ( f ) is the shielding effectiveness S of the shielded wire W ( f ), at this time the induced current I in S2 LLSC_X ( f ) is: the induced current I of the harness of the tested equipment after changing to unshielded wire LLSC_W ( f ), I LLSC_W ( f ) is calculated as follows: I LLSC_W ( f )= I LLSC ( f ) / S W ( f )。

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