Civil aircraft airborne equipment reliability data verification scheme selection method

Abstract

The invention provides a civil aircraft airborne equipment reliability data verification scheme selection method. Obtaining an I, II and III type function failure state list of the target system; determining the influence level of each airborne device of the target system on safety and reliability; analyzing the reliability data conformity verification method of the system airborne equipment to form a preliminary verification method list; for equipment which needs to be subjected to a necessary reliability test in the preliminary verification method list, preliminarily judging reliability test items which need to be carried out by the equipment; selecting a reliability identification test or a durability / life test according to product characteristics and fault reasons of fault modes having great influence on safety, and obtaining a preliminary reliability test item list of the system airborne equipment; and forming a test item list based on the preliminary reliability test item list of the system airborne equipment. According to the method, the problem of reliability data verification scheme selection of the civil aircraft airborne equipment can be efficiently solved.

Description

Technical Field

[0001] This invention belongs to the field of reliability data verification technology in reliability engineering, and specifically relates to a method for selecting a reliability data verification scheme for civil aircraft airborne equipment. Background Technology

[0002] As an indispensable component of aircraft systems, the reliability level of airborne equipment is a crucial factor affecting aircraft safety and airworthiness. Domestic airworthiness regulations explicitly require that airborne equipment undergo thorough reliability analysis and verification to demonstrate its ability to operate within the expected operating environment and service life, meeting the prescribed reliability requirements. These verification results serve as vital technical evidence supporting aircraft type certification (TC) and continued airworthiness.

[0003] As the integration level and complexity of airborne equipment in civil aircraft systems continue to increase, their types and functions are also becoming increasingly diversified. Currently, when selecting reliability data verification schemes for different airborne equipment, engineering practice mainly relies on historical experience or similar project practices. This approach has significant limitations and is prone to problems such as over-verification or under-verification due to inappropriate scheme selection. For example, using overly stringent testing schemes for non-critical or high-reliability equipment can lead to lengthy testing cycles and wasted resources; insufficient conservatism in the scheme or inadequate data utilization may prevent the provision of the reliability level proof required for airworthiness certification of the target equipment, or even create safety hazards or cause certification delays.

[0004] In summary, current technologies lack a scientific, systematic, and standardized method to efficiently select the optimal and airworthiness-compliant solution from multiple reliability data verification schemes based on the specific characteristics of airborne equipment. This lack of a method not only restricts the efficiency of airborne equipment reliability engineering implementation but may also affect aircraft development cycles and airworthiness safety. Currently, no specific method for selecting airborne equipment reliability data verification schemes has been found in publicly available information in the domestic civil aircraft field. Summary of the Invention

[0005] The purpose of this invention is to provide a method for selecting a reliability data verification scheme for airborne equipment in civil aircraft. This invention can efficiently solve the problem of selecting a reliability data verification scheme for airborne equipment in civil aircraft.

[0006] Technical solution. A method for selecting a reliability data verification scheme for airborne equipment in civil aircraft, comprising: S1. Based on the functional hazard analysis of civil aircraft and the functional hazard analysis of the target system, a list of Class I, II, and III functional failure states of the target system is obtained; S2. Based on the preliminary security analysis and product importance analysis of the target system, determine the impact level of each airborne device of the target system on security and reliability; S3. Based on the magnitude of the safety impact, analyze the reliability data compliance verification methods of the system's airborne equipment and form a preliminary verification method list; S4. For the equipment in the preliminary verification method list that still needs to undergo necessary reliability tests, conduct a reliability test item analysis and make a preliminary determination of the reliability test items that need to be carried out on these equipment; S5. Based on the product characteristics and the causes of failure modes that have a significant impact on safety, select reliability qualification tests or durability / life tests to obtain a preliminary list of reliability test items for the system's airborne equipment; S6. Based on the preliminary reliability test item list of the system's airborne equipment, and in conjunction with the current development progress of civil aircraft, analyze the feasibility and necessity of implementing and verifying each test, confirm the necessary reliability test items for each airborne equipment, and form a test item list.

[0007] The aforementioned method for selecting a reliability data verification scheme for airborne equipment in civil aircraft also includes: S7. Based on the test item list, complete the selection of the reliability data verification method for civil aircraft airborne equipment, and form the final target system airborne equipment reliability data verification scheme.

[0008] In the aforementioned method for selecting a reliability data verification scheme for civil aircraft airborne equipment, S2 classifies the impact levels of safety and reliability into 5 levels: Level 1 - Major Safety Impact: A failure mode of the equipment is a second-order minimal cut set of a Type I failure state, or a single point of failure of a Type II failure state. Level 2 - Major safety impact: Non-Level 1 equipment, but with failure modes that are affected by Class II or Class III. Level 3 - Significant Reliability Impact: Equipment that is not Level 1 or 2, but whose reliability is of critical importance. Level 4 - Only affects release: Equipment that is not Level 1, 2, or 3, but will malfunction and cannot be released; Level 5 - Other: None of Levels 1-4 above, with minimal impact on safety and reliability.

[0009] In the aforementioned method for selecting a reliability data verification scheme for civil aircraft airborne equipment, S3 is based on the following fundamental principles: Principle a: In the failure mode failure rate data of airborne equipment, service / operational data should be used first to assess the reliability level; Principle b: If there is no service / operation data, the verification mainly relies on consulting standards and relevant manuals to predict the reliability of components / parts, and to predict the failure mode failure rate of the equipment according to the formula. For equipment affected by Principle c, Level 1, Level 2, and Level 3, in addition to reliability prediction, necessary data work is required to improve the credibility of the predicted values. Such data work includes: service / operation reliability data and reliability verification test data of similar products to corroborate the predictions, necessary reliability test data to corroborate the predictions, and continuous monitoring of aircraft flight test and operation data. For equipment affected by principle d and level 4, the reliability data verification method mainly considers, in addition to the reliability prediction, continuous monitoring of its flight test and operation data on the aircraft and periodic assessment of its reliability level. For principle e, level 5 affected equipment, only reliability predictions are used.

[0010] In the aforementioned method for selecting a reliability data verification scheme for airborne equipment in civil aircraft, under principle b, the formula is: Failure rate of a failure mode = Failure rate of a single device. The frequency ratio of failure modes.

[0011] In the aforementioned method for selecting a reliability data verification scheme for civil aircraft airborne equipment, the analysis process in S4 is as follows: The failure rates of the predicted failure modes obtained from equipment failure mode and impact analysis are input into the fault tree of the system safety assessment to obtain the probability verification λ of system type I, II, and III failure states. RE ; with λ RE And the failure state probability requirement λ SA Based on analysis and comparison, according to λ RE ≤0.1λ SA 0.1λ SA <λ RE ≤0.75λ SA 0.75λ SA <λ RE ≤2.5λ SA These devices are categorized into three groups, and the reliability tests required for these devices are preliminarily determined.

[0012] In the aforementioned method for selecting a reliability data verification scheme for airborne equipment of civil aircraft, in S5, based on the applicability and matching degree of the equipment type and its test methods in the system, electronic products undergo reliability identification tests, environmental stress screening, reliability simulation tests, reliability enhancement tests, and reliability baseline tests; mechanical products undergo durability / life tests and reliability simulation tests; and all of the above tests are carried out for electromechanical products.

[0013] In the aforementioned method for selecting a reliability data verification scheme for airborne equipment in civil aircraft, in S1, the target system is a hydraulic power source system, and the corresponding list of functional failure states for categories I, II, and III is as follows: .

[0014] Advantages of this invention: This invention addresses the current lack of a systematic, standardized, and quantifiable method for selecting reliability data verification schemes, which easily leads to over-verification or under-verification due to inappropriate scheme selection. It proposes a method for selecting reliability data verification schemes for airborne equipment in civil aircraft. Based on a proposed airborne equipment impact level classification system, this invention conducts a preliminary screening of available reliability data verification methods, using a comparative analysis of system fault tree assessment results and failure state probability requirements as the core decision-making basis, combined with product characteristics and development progress. Ultimately, it determines the necessary and suitable reliability data verification schemes for each target airborne device in the system. This invention overcomes the shortcomings of existing technologies that lack a standardized and systematic selection process, thus scientifically and efficiently solving the problem of selecting reliability data verification schemes for airborne equipment in civil aircraft.

[0015] This invention effectively solves the problems of subjectivity and uncertainty in the selection of reliability verification schemes for airborne equipment in civil aircraft by establishing a systematic and standardized method. Compared with traditional methods that rely on engineering experience, this invention has the following significant advantages: First, by constructing a quantifiable classification system for the impact of airborne equipment and establishing clear screening principles, the previous qualitative decision-making based on individual experience was transformed into a standardized analysis process based on unified criteria. This transformation effectively eliminated the arbitrariness of human judgment, made the verification scheme selection process repeatable and traceable, and significantly improved the credibility and persuasiveness of airworthiness compliance demonstrations.

[0016] Secondly, by comparing the system fault tree assessment results with the failure state probability requirements as the core decision-making basis, the mechanism ensures a precise match between verification intensity and equipment safety criticality. This mechanism fundamentally avoids the waste of resources caused by "over-verification" while eliminating the approval risks and safety hazards that may result from "insufficient verification." Furthermore, by comprehensively considering multi-dimensional constraints such as product characteristics and development schedule, the mechanism achieves synergistic optimization of technical and engineering feasibility, significantly enhancing engineering applicability in complex model development environments.

[0017] Finally, this method constructs a complete framework from initial screening to comprehensive decision-making, possessing the flexibility to adapt to different equipment types, data sources, and development stages. This framework supports both precise solution selection for individual devices and comprehensive planning of verification schemes for all equipment across the entire aircraft. By deeply embedding airworthiness requirements into the decision-making logic, it provides clear and auditable empirical evidence for qualification certification, comprehensively strengthening the airworthiness compliance demonstration capability and effectively accelerating the certification process.

[0018] In summary, this invention achieves a significant shift from experience-driven to model- and criterion-driven approaches, comprehensively improving the efficiency, economy, and reliability of verification work while ensuring safety. Attached Figure Description

[0019] Figure 1 Flowchart for selecting a reliability data verification scheme for civil aircraft airborne equipment. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0022] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] Example 1. A method for selecting a reliability data verification scheme for airborne equipment in civil aircraft, see [link to example]. Figure 1 , Step 1: Based on the functional hazard analysis of civil aircraft and the functional hazard analysis of the system to be analyzed (hereinafter referred to as the target system), the Class I, Class II and Class III functional failure states of the target system are obtained. This list of major failure states is an important basis for the reliability data conformity verification method for determining the failure mode failure rate of the basic event.

[0024] Step 2: Based on the preliminary security analysis and product importance analysis of the target system, determine the impact level of each airborne device of the target system on security and reliability.

[0025] In step 2 above, the impact levels on safety and reliability can be divided into 5 levels according to the following principles: a) Level 1 - Significant safety impact: A failure mode of the equipment is a second-order minimal cut set of a Type I failure state, or a single point of failure of a Type II failure state. b) Level 2 - Major safety impact: Non-Level 1 equipment, but with failure modes that have a Class II or Class III impact (i.e., the preliminary safety analysis report of the system proposes quantitative safety requirements). c) Level 3 - Equipment with significant reliability impact: Equipment that is not Level 1 or 2, but whose reliability product importance is significant; d) Level 4 - Only affects release: equipment that is not Level 1, 2, or 3, but will malfunction and cannot be released; e) Level 5 - Others: None of the above levels 1-4, and have a relatively small impact on safety and reliability.

[0026] Step 3: Following the basic principles below, and based on the magnitude of the safety impact, analyze the reliability data compliance verification methods of the system's airborne equipment to form a preliminary verification method list.

[0027] The above basic principles are as follows: a) In the failure mode failure rate data of airborne equipment, service / operational data should be used first to assess the reliability level; b) If no service / operational data is available, verification mainly relies on consulting standards and relevant manuals to predict the reliability at the component / part level, and using the formula to predict the failure mode failure rate of the equipment (formula: failure mode failure rate = single device failure rate). (Failure mode frequency ratio) c) For Level 1, Level 2 (significant and major safety impacts) and Level 3 (relatively significant reliability impacts) affected equipment, in addition to reliability projections, necessary data work is required to enhance the credibility of the projected values. Such data work includes: service / operational reliability data and reliability verification test data of similar products to corroborate the projections, necessary reliability test evidence, and continuous monitoring of aircraft flight test and operation data. d) Level 4 (only affecting release) equipment, with no major direct safety impact, its reliability data verification method mainly considers continuous monitoring of its flight test and operation data on the aircraft and periodically assessing its reliability level, in addition to reliability prediction. e) Level 5 (other) impacts on equipment have relatively small effects on safety and reliability, therefore only reliability prediction is used.

[0028] Step 4: For equipment requiring further reliability testing as described in Step 3's preliminary verification method, conduct reliability test item analysis. Input the predicted failure mode failure rates (predicted reliability data) from the equipment failure mode and effects analysis into the fault tree for system safety assessment to obtain the probability verification λ for system Type I, II, and III failure states. RE To evaluate the results λ RE And the failure state probability requirement λ SA Based on analysis and comparison, according to λ RE ≤0.1λ SA 0.1λ SA <λ RE ≤0.75λ SA 0.75λ SA <λ RE ≤2.5λ SA These devices are categorized into three groups, and the reliability tests required for these devices are preliminarily determined.

[0029] Step 5: Select reliability qualification tests or durability / life tests based on product characteristics and failure modes that have a significant impact on safety, and obtain a preliminary reliability test list for the system's airborne equipment.

[0030] Depending on the type of equipment in the system and the suitability of its testing methods, electronic products can undergo reliability qualification tests, environmental stress screening, reliability simulation tests, reliability enhancement tests, and reliability baseline tests; mechanical products can undergo durability / life tests and reliability simulation tests; and all of the above tests can be carried out on electromechanical products.

[0031] Step 6: Based on the preliminary reliability test list of the airborne equipment in Step 5, and in conjunction with the current development progress of civil aircraft, analyze the feasibility and necessity of implementing and verifying each test, confirm the necessary reliability test items for each airborne equipment, and form a test item list.

[0032] Step 7: Based on the test item list, complete the selection of the reliability data verification method for civil aircraft airborne equipment, and form the final target system airborne equipment reliability data verification scheme.

[0033] Example 2. This example uses a hydraulic power source system of a civil aircraft as the target object, selects a method for verifying the reliability data of its airborne equipment, and confirms the final verification scheme. See [link to example]. Figure 1 The implementation steps are as follows: Step 1: Obtain a list of major failure states of the hydraulic power source system from the functional hazard analysis of the aircraft-level civil aircraft and the functional hazard analysis of the hydraulic power source system. Examples of failure states with different hazard levels are extracted and illustrated in Table 1. Table 1. List of Failure States for Hydraulic Power System (Class I, II, and III) .

[0034] Step 2: Based on the preliminary safety analysis and product importance analysis of the hydraulic power system, determine the impact level of each airborne device of the hydraulic power system on safety and reliability, and extract examples of different impact levels, as shown in Table 2.

[0035] Table 2 Classification of Safety and Reliability Impact Levels of Hydraulic Power System Airborne Equipment .

[0036] Step 3: Based on the magnitude of the safety impact, analyze the reliability data compliance verification methods of the airborne equipment of the hydraulic power source system and form a preliminary verification method list, as shown in Table 3.

[0037] The specific analysis process is as follows: Step 3.1: Conduct preliminary verification method analysis for the system level 1 affected devices.

[0038] a) Hydraulic electric switch The hydraulic electric switch is used to cut off the flow of hydraulic oil to the hydraulic pump. It is installed in the engine compartment area and is mainly composed of parts such as cover, pin, sealing ring, rocker arm assembly, valve, housing, safety valve assembly, sealing ring, pipe joint, plug cap, locking pin, nameplate, screw, washer, connecting bracket, sealing ring, electric mechanism, disc spring, washer, and sealing ring.

[0039] The hydraulic electric switch (XX-01) is a newly developed domestic product with no service / operation data. In accordance with the basic principles of step 3 above, a reliability prediction method is adopted, and necessary reliability tests need to be carried out to improve the credibility of the predicted value.

[0040] b) Right worktable control components The right-hand console control unit is used by pilots during flight and ground maintenance to control aircraft systems and indicate the operational status of equipment via indicator lights. The entire right-hand console control unit consists of a panel assembly (including a light guide plate, mounting plate, toggle switches, indicator lights with push-button switches, press switches, indicator light printed circuit board components, long screws, short screws, etc.), connector mounting plate components, housing components, and standard parts.

[0041] The right worktable control component (XX-02) is a modification of the existing mature product (similar product) by supplier XX factory, but it lacks effective service data. To improve the credibility of the predicted value, necessary reliability tests need to be carried out.

[0042] Step 3.2: Conduct preliminary verification method analysis for system level 2 affected devices.

[0043] a) Housing oil return filter assembly The housing return oil filter assembly is mainly used to filter mechanical impurities in the housing return oil circuit, ensuring system cleanliness. It also features a contamination exceeding limit indicator and a bypass function. The housing return oil filter assembly mainly consists of functional components such as a self-sealing bypass device assembly, filter element, filter cup, differential pressure indicator, and pressure signaler.

[0044] The housing oil return filter assembly - EDP, EMP (XX-03, XX-04) are newly developed domestic products with no service / operation data. In accordance with the basic principles of step 3 above, the reliability prediction method is adopted, and necessary reliability tests need to be carried out to improve the credibility of the predicted values.

[0045] b) Temperature flow solenoid valve The thermostatic solenoid valve features valve core position indication, throttling, and filtering functions. It heats the hydraulic oil through the heat generated by the pressure loss of the high-pressure hydraulic fluid flowing through the valve. It also effectively prevents blockage of the flow-limiting orifice. The thermostatic solenoid valve mainly consists of an outer casing, adjusting washer, spring washer, heat shrink tubing, mounting base, microswitch, screw, lead wire, gasket, threaded sleeve, sealing gasket, housing, valve seat, socket, fast recovery rectifier diode, and insulating base.

[0046] The temperature flow solenoid valve (XX-05) is a modified version of the existing mature product (similar product) by supplier XX factory, but it lacks effective service data. To improve the credibility of the predicted value, it is necessary to carry out the necessary reliability test.

[0047] Step 3.3: Conduct preliminary verification method analysis for devices affected by Level 3 of the system.

[0048] There are no Level 3 affected devices in this example.

[0049] Step 3.4: Conduct preliminary verification method analysis for devices affected by Level 4 of the system.

[0050] a) Brake accumulator Brake accumulators are used to store hydraulic energy, providing sufficient braking pressure for emergency braking systems; during parking braking, they ensure that the aircraft brakes within a specified time and the pressure does not drop to an unacceptable level. The brake accumulator has a cylindrical piston structure and mainly consists of components such as an outer cylinder, piston, end cap, nozzle, air chamber connector, inflation valve, and pressure sensor.

[0051] The brake accumulator (XX-06) is a newly developed domestic product with no service / operation data and no major direct safety impact. According to the basic principles of step 3 above, using the reliability prediction method, it is still necessary to continuously monitor its flight test and operation data on the aircraft and periodically assess its reliability level.

[0052] b) Priority valve The priority valve is used in aircraft hydraulic systems. Its main function is to shut off the downstream (B port) mission system when the system flow is insufficient, thereby prioritizing the pressure supply to the mission system at port A. The priority valve mainly consists of inlet pipe fittings, inlet end caps, adapters, housings, lift valve cores, lift valve springs, pistons, main springs, outlet end caps, and outlet pipe fittings.

[0053] The priority valve (XX-07) is a newly developed domestic product with no service / operation data and no major direct safety impact. According to the basic principles of step 3 above, using the reliability prediction method, it is still necessary to continuously monitor its flight test and operation data on the aircraft and periodically assess its reliability level.

[0054] Step 3.5: Conduct preliminary verification method analysis for devices affected by Level 5 of the system.

[0055] a) Ground pump booster connector The ground pump booster connector is a component of the aircraft hydraulic power system. Its main function is to transfer hydraulic fluid from the ground hydraulic power source (port B) to the aircraft system when connected to the ground hydraulic power source, via port A. The ground pump booster connector mainly consists of a cover assembly, valve, protective ring, star-shaped seal, housing, spring, guide sleeve, slotted conical set screw, sealing ring, protective ring, and connecting nozzle.

[0056] The ground pump booster connector (XX-08) is a newly developed domestic product with no service / operation data. Its impact on safety and reliability is relatively small. According to the basic principle of step 3 above, the reliability prediction method is adopted without the need for additional data work.

[0057] b) Sampling valve The sampling valve is a component of the aircraft hydraulic power system. Its main function is to collect hydraulic fluid from the aircraft's hydraulic system. The sampling valve mainly consists of a nozzle, curved core, bushing, spring, valve assembly, housing, sampling core, cap, sealing ring, and protective ring.

[0058] The sampling valve (XX-09) is a newly developed domestic product with no service / operation data. Its impact on safety and reliability is relatively small. According to the basic principle of step 3 above, the reliability prediction method is adopted without the need for additional data work.

[0059] Step 4: For equipment requiring further reliability testing in the preliminary verification method, conduct reliability test item analysis, and input the failure mode failure rate (reliability prediction data) predicted by the equipment FMEA into the fault tree of the system safety assessment to obtain the probability verification λ of system type I, II, and III failure states. RE To evaluate the results λ RE And the failure state probability requirement λ SA Based on the analysis and comparison, the reliability test items that need to be carried out for these devices were initially determined. The preliminary analysis results of the reliability test items for airborne equipment of hydraulic power source system are shown in Table 3.

[0060] Table 3 Classification of Safety and Reliability Impact Levels of Hydraulic Power System Airborne Equipment .

[0061] Step 5: Select reliability qualification test or durability / life test based on product characteristics and failure modes that have a significant impact on safety, and obtain a preliminary reliability test item list for the hydraulic system airborne equipment, as shown in Table 4.

[0062] Table 4. List of Preliminary Reliability Test Items for Hydraulic Power System Airborne Equipment .

[0063] Step 6: Based on the preliminary reliability test list of the airborne equipment of the hydraulic power system in Step 5, and in conjunction with the current development progress of civil aircraft, analyze the feasibility and necessity of implementing and verifying each test, confirm the necessary reliability test items for each airborne equipment, and form a test item list.

[0064] Step 6.1: Analyze the feasibility and necessity of implementing and verifying reliability simulation tests and reliability enhancement tests in light of the current development progress of civil aircraft.

[0065] The main purpose of reliability simulation tests and reliability enhancement tests is to identify product weaknesses and make design improvements to enhance product reliability. These tests are suitable for the product design and development phase, effectively identifying design flaws and reducing risks during the model flight test phase. Currently, the design configurations of all airborne equipment in the hydraulic power system of the XX model aircraft have been finalized and MC9 qualification tests have been completed. Therefore, it is not suitable to conduct further reliability simulation tests and enhancement tests during the development phase. Thus, reliability simulation tests (optional) and reliability enhancement tests (optional) are not to be conducted for the time being in the reliability test items for the various equipment listed in Table 4 above. If the failure rate of the equipment deviates significantly from the expected reliability value during subsequent flight tests / operations, these tests will be added to improve its reliability level.

[0066] Step 6.2: Analyze the feasibility and necessity of implementing and verifying reliability baseline tests in light of the current progress of civil aircraft development.

[0067] Reliability baseline testing is a method to assess product reliability by simulating actual usage environments. Its main purpose is to eliminate early failures before product installation to reduce flight test risks. The test duration is generally 200-300 hours. Currently, the cumulative flight test time of the XX model aircraft has reached 5000 flight hours, and the equipment operating time has far exceeded the test duration. Conducting reliability baseline testing is no longer of practical significance for verifying reliability data. Therefore, in the reliability test items of each piece of equipment in Table 4, the reliability baseline test (optional) is replaced by monitoring the flight test data on the aircraft and evaluating reliability.

[0068] Step 6.3: Based on the product characteristics, confirm the reliability test items that need to be carried out for each airborne device.

[0069] a) Hydraulic electric switch The failure mode "unable to disconnect" of hydraulic electric switches is a second-order minimal cut set of Type I failure states. Its failure causes are mainly wear and breakage of components such as rocker arm assembly, valve, connecting frame, and electric mechanism. It is more suitable to use durability / life test.

[0070] b) Right Work Console The main fault modes of the right work console are "unloading switch cannot unload", "unloading switch is mistakenly turned on", and "emergency accumulator switch is mistakenly turned on". The fault criteria are mainly whether various indicator lights, switch control signals and lighting indication functions are malfunctioning. They are not closely related to the wear and breakage of parts, and are more suitable for reliability qualification tests.

[0071] c) Temperature flow solenoid valve The expected failure rate for the thermodynamic solenoid valve is 1.39 × 10⁻⁶. -6 / h, i.e., MTBF is 719313 hours, its safety-impacting failure mode "valve cannot open" is the failure state "no-notification hydraulic source system 3 sources cannot heat (Class III)" Class III second-order cut set, probability verification λ RE =1.8×10 -6 / h, compared with 0.1λ in the reliability test project analysis SA The classification requirements are similar; furthermore, the failure mode "valve cannot close" is a failure state "unable to close hydraulic source system 3 source error heating (Class III)" Class III second-order cut set, probability verification λ RE =1.67×10 -7 / h, which is much smaller than 0.1λ in the reliability test project analysis. SAThe required classification criteria apply. Therefore, the predicted reliability of the temperature flow solenoid valve has a large margin of safety in terms of probability, and there is no need to conduct durability / life tests or reliability assessments for the time being. Instead, continuous monitoring of its flight test and operational data on the aircraft and periodic evaluation of its reliability level will be adopted.

[0072] Step 6.4: Organize the above analysis and form a list of reliability test items for airborne equipment of the hydraulic power source system, as shown in Table 5.

[0073] Table 5 List of Reliability Test Items for Hydraulic Power System Airborne Equipment .

[0074] Step 7: Based on the analysis of the above steps, complete the selection of the reliability data verification method for the aircraft's airborne equipment, and form the final reliability data verification scheme for the airborne equipment of the hydraulic source system, as shown in Table 6.

[0075] Table 6 Reliability Verification Scheme for Hydraulic Power System Airborne Equipment

[0076] The above-described embodiments merely illustrate the implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A method for selecting a reliability data verification scheme for airborne equipment in civil aircraft, characterized in that, include: S1. Based on the functional hazard analysis of civil aircraft and the functional hazard analysis of the target system, a list of Class I, II, and III functional failure states of the target system is obtained; S2. Based on the preliminary security analysis and product importance analysis of the target system, determine the impact level of each airborne device of the target system on security and reliability; S3. Based on the magnitude of the safety impact, analyze the reliability data compliance verification methods of the system's airborne equipment and form a preliminary verification method list; S4. For the equipment in the preliminary verification method list that still needs to undergo necessary reliability tests, conduct a reliability test item analysis and make a preliminary determination of the reliability test items that need to be carried out on these equipment; S5. Based on the product characteristics and the causes of failure modes that have a significant impact on safety, select reliability qualification tests or durability / life tests to obtain a preliminary list of reliability test items for the system's airborne equipment; S6. Based on the preliminary reliability test item list of the system's airborne equipment, and in conjunction with the current development progress of civil aircraft, analyze the feasibility and necessity of implementing and verifying each test, confirm the necessary reliability test items for each airborne equipment, and form a test item list.

2. The method for selecting a reliability data verification scheme for civil aircraft airborne equipment according to claim 1, characterized in that, Also includes: S7. Based on the test item list, complete the selection of the reliability data verification method for civil aircraft airborne equipment, and form the final target system airborne equipment reliability data verification scheme.

3. The method for selecting a reliability data verification scheme for civil aircraft airborne equipment according to claim 1, characterized in that, In S2, the impact levels on security and reliability are divided into 5 levels: Level 1 - Major Safety Impact: A failure mode of the equipment is a second-order minimal cut set of a Type I failure state, or a single point of failure of a Type II failure state. Level 2 - Major safety impact: Non-Level 1 equipment, but with failure modes that are affected by Class II or Class III. Level 3 - Significant Reliability Impact: Equipment that is not Level 1 or 2, but whose reliability is of critical importance. Level 4 - Only affects release: Equipment that is not Level 1, 2, or 3, but will malfunction and cannot be released; Level 5 - Other: None of Levels 1-4 above, with minimal impact on safety and reliability.

4. The method for selecting a reliability data verification scheme for civil aircraft airborne equipment according to claim 1, characterized in that, In S3, the analysis is based on the following fundamental principles: Principle a: In the failure mode failure rate data of airborne equipment, service / operational data should be used first to assess the reliability level; Principle b: If there is no service / operation data, the verification mainly relies on consulting standards and relevant manuals to predict the reliability of components / parts, and to predict the failure mode failure rate of the equipment according to the formula. For equipment affected by Principle c, Level 1, Level 2, and Level 3, in addition to reliability prediction, necessary data work is required to improve the credibility of the predicted values. Such data work includes: service / operation reliability data and reliability verification test data of similar products to corroborate the predictions, necessary reliability test data to corroborate the predictions, and continuous monitoring of aircraft flight test and operation data. For equipment affected by principle d and level 4, the reliability data verification method mainly considers, in addition to the reliability prediction, continuous monitoring of its flight test and operation data on the aircraft and periodic assessment of its reliability level. For principle e, level 5 affected equipment, only reliability predictions are used.

5. The method for selecting a reliability data verification scheme for civil aircraft airborne equipment according to claim 4, characterized in that, In principle b, the formula is: Failure rate of a failure mode = Failure rate of a single device The frequency ratio of failure modes.

6. The method for selecting a reliability data verification scheme for civil aircraft airborne equipment according to claim 1, characterized in that, In S4, the analysis process is as follows: The failure rates of the predicted failure modes obtained from equipment failure mode and impact analysis are input into the fault tree of the system safety assessment to obtain the probability verification λ of system type I, II, and III failure states. RE ; with λ RE And the failure state probability requirement λ SA Based on analysis and comparison, according to λ RE ≤0.1λ SA 0.1λ SA <λ RE ≤0.75λ SA 0.75λ SA <λ RE ≤2.5λ SA These devices are categorized into three groups, and the reliability tests required for these devices are preliminarily determined.

7. The method for selecting a reliability data verification scheme for civil aircraft airborne equipment according to claim 1, characterized in that, In S5, based on the applicability and matching degree of the equipment type and test methods in the system, electronic products undergo reliability qualification tests, environmental stress screening, reliability simulation tests, reliability enhancement tests, and reliability baseline tests; mechanical products undergo durability / life tests and reliability simulation tests; and electromechanical products undergo all of the above tests.

8. The method for selecting a reliability data verification scheme for civil aircraft airborne equipment according to claim 1, characterized in that, In S1, the target system is a hydraulic power source system, and the corresponding list of functional failure states for categories I, II, and III is as follows:

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