Key characteristic control-oriented airborne equipment FMEA working method

Abstract

The invention relates to an airborne equipment FMEA working method for key characteristic control. The airborne equipment FMEA working method sequentially comprises the following steps of S1, DFMEA analysis; s2, key parts and characteristics are determined; and step S3, carrying out PFMEA analysis. Potential risks can be recognized in advance, and design and process failure modes possibly occurring to airborne equipment can be accurately analyzed through precise measurement. For example, for a signal transmission module of airborne communication equipment, precise measurement can help to determine reasonable ranges of parameters such as signal strength and frequency, factors possibly causing signal transmission faults, such as poor contact, element aging and other potential problems in the design or manufacturing process, are found in advance, and then measures are taken in advance to prevent the faults.

Description

Technical Field

[0001] The present invention relates to the field of aviation and aerospace related technologies, and in particular to an airborne equipment FMEA working method oriented to key characteristic control. Background Art

[0002] FMEA is a systematic method to determine the failure modes of systems, components, functions or individual parts and their impact on higher-level designs. FMEA can be either qualitative or quantitative, and can be implemented on all types of systems (including electrical, electronic or mechanical systems). FMEA can be generally divided into design FMEA (DFMEA) and process FMEA (PFMEA) according to the different stages of use. DFMEA is mainly an analysis technique used by personnel responsible for product design to ensure that various potential failure modes and their related causes / mechanisms have been fully considered and specified to the extent possible. PFMEA mainly aims to formulate improvement measures for process weaknesses based on the risk size of the failure mode, based on the assumption that the designed product can meet the design requirements, for the possible failure modes, causes and all impacts on the product in each process step during the production process, and improve the reliability of the product. DFMEA includes functional FMEA, hardware FMEA and software FMEA. Different forms of FMEA will be used at various stages of the product life cycle, as shown in the table, but the fundamental purpose is to discover various defects and weak links of the product from different angles, and take effective improvement and compensation measures to improve its reliability level.

[0003] Table 1 FMEA methods used in each stage:

[0004]

[0005] DFMEA helps optimize design features by identifying potential failure modes and their impact on flight safety in the early stages of design. For example, in the design of airborne hydraulic systems, it is necessary to analyze the impact of high-pressure pipeline rupture, actuator failure and other modes on flight control, and formulate preventive measures in combination with airworthiness requirements (such as redundant design and fault tolerance). After DFMEA is carried out, it is also necessary to carry out the Failure Mode and Effect Summary (FMES). The FMES work is to summarize the lower-level failure modes with the same impact in the FMEA analysis results, sum their failure rates, and treat the impact as a failure mode of FMES to further analyze its possible impact on the upper-level system. FMES can be used as part of FMEA, where the analysis results are used to summarize the same impact of different failure modes on the system or equipment, treat the impact as a single point failure, and simplify the fault tree analysis by reducing the number of gates at the lowest level.

[0006] PFMEA is about risk control in the manufacturing and assembly process. PFMEA focuses on potential failures in the production process of airborne equipment, such as precision sensor assembly deviations, welding process defects, etc. Through process flow charts and function network diagrams, key control points (such as special characteristic parameters) are identified, and detection methods (such as automated detection technology) are developed.

[0007] The defects of the prior art are as follows:

[0008] 1. FMEA cannot cover all potential failure modes: Due to the diversity and complexity of failure modes, FMEA is difficult to cover all failure modes.

[0009] 2. The RPN quantitative analysis of FMEA relies more on subjective analysis. The calculation method of RPN (the product of severity, occurrence rate and detection rate) has mathematical problems, because the ordinal score is generated subjectively and there is no defined distance measurement. As a result, the calculation result of RPN may be inaccurate and the failure rate of failure mode for the product cannot be well calculated and analyzed.

[0010] 3. Failure mode impact analysis is not thorough, and it is difficult to reflect the impact of airborne equipment failure modes on airborne equipment, systems and aircraft based on the actual architecture of the aircraft and airborne equipment. FMEA usually focuses on the analysis of a single failure mode, while ignoring the connection and impact between failure modes, which may lead to insufficient risk analysis of complex systems.

[0011] 4. Limitations of detection methods: The word "detection" in FMEA is more associated with inspection (containment) rather than prevention (control). This may cause the team to only consider containment techniques without considering preventive measures, thus affecting the comprehensiveness and effectiveness of the analysis.

[0012] 5. Limitations of qualitative analysis: FMEA is primarily a qualitative analysis tool that relies on the team’s subjective judgment rather than being based on quantifiable data, which may lead to inaccurate analysis results.

[0013] In view of the above-mentioned defects, the designers have actively carried out research and innovation in order to create an FMEA working method for airborne equipment oriented to key characteristic control, making it more valuable for industrial use. Summary of the invention

[0014] In order to solve any of the above technical problems, the purpose of the present invention is to provide an airborne equipment FMEA working method oriented to key characteristic control.

[0015] To achieve the above object, the present invention adopts the following technical solution:

[0016] An airborne equipment FMEA working method for key characteristic control includes the following steps in sequence:

[0017] Step S1, DFMEA analysis:

[0018] Step S101, analysis object definition;

[0019] Step S102: product function analysis;

[0020] Step S103, drawing a function and reliability block diagram;

[0021] Step S104, design failure mode analysis;

[0022] Step S105: analyzing the causes of design failure;

[0023] Step S106, task phase / working mode definition;

[0024] Step S107, design failure impact analysis;

[0025] Step S108, failure mode reliability data analysis;

[0026] Step S109, failure impact level analysis;

[0027] Step S110: cascade impact analysis;

[0028] Step S111, detection method analysis;

[0029] Step S112: corrective measures;

[0030] Step S113, FMES analysis;

[0031] Step S114, fill in FMEA and FMES analysis tables;

[0032] Step S2: Determination of key components and characteristics:

[0033] Step S201, determine key parts and important parts;

[0034] Step S202, identifying the critical characteristics of the critical parts;

[0035] Step S203, carrying out the transmission of key characteristics in D / PFMEA;

[0036] Step S3: PFMEA analysis:

[0037] Step S301, system definition;

[0038] Step S302: process failure mode analysis;

[0039] Step S303, process failure cause analysis;

[0040] Step S304: process failure impact analysis;

[0041] Step S305: AP and RPN analysis;

[0042] Step S306: Formulate improvement measures;

[0043] Step S307: Improved AP and RPN analysis;

[0044] Step S308: Track the implementation status and optimize the D / PFMEA and key characteristic management of key parts.

[0045] As a further improvement of the present invention, in step S101, the level of the analyzed product is defined; in step S102, the functions of the product are analyzed and the product function definition is given; in step S103, based on the product function definition and architecture, a product function and reliability block diagram is drawn.

[0046] As a further improvement of the present invention, in step S104, the failure mode is analyzed according to the functional description of the product, and then according to the hardware characteristics of the product, in the requirements of the failure criteria, all hardware failure modes are found and corresponded with the functional failure modes to ensure that all functional failure modes have corresponding hardware failure modes; in step S105, the causes of the failure modes are found, including direct causes such as product design defects and manufacturing defects that lead to functional failure or potential failure of the product, and indirect causes of product failure caused by external factors; in step S106, the task stage / working mode of the analyzed product is determined, and each task stage / working mode needs to be considered one by one.

[0047] As a further improvement of the present invention, in step S107, the influence of each failure mode on the use, function and status of the product itself or other products is found, and its severity is analyzed; in step S108, the failure mode related reliability data including but not limited to the failure mode failure rate and frequency ratio reliability data are obtained; in step S109, the failure impact level includes the hazard level and severity category, which are filled in according to the level of the analysis object.

[0048] As a further improvement of the present invention, in step S111, the detection method includes but is not limited to visual inspection, in-situ detection and off-situ detection; in step S112, the corrective measures are divided into design improvement measures and usage maintenance measures.

[0049] As a further improvement of the present invention, in step S113, the analyst checks the consistency of the failure impact of the FMEA analysis results; in step S114, the FMEA table includes but is not limited to analysis object information, FMEA code, failure mode, failure cause, failure impact, failure rate related data, impact level, detection method and corrective measures; the FMES table includes but is not limited to FMES number, failure mode, failure rate, task stage information, failure symptoms and failure cause.

[0050] As a further improvement of the present invention, in step S202, the core functions and auxiliary functions of the equipment are firstly clarified, and their accuracy, response time and reliability are evaluated; then, based on FHA and PSSA, the relevant DFMEA failure modes of key parts in catastrophic, dangerous, major, flight interruption and dispatch interruption failure states are determined, and corresponded with the core functions of the equipment, and the key characteristics identified in the design process of the equipment are determined; finally, in the manufacturing process, the manufacturing and assembly process procedures of the key characteristics related to the equipment are identified through PFMEA; in step S203, the failure causes related to manufacturing in DFMEA are sorted out as the input of PFMEA, and then its key characteristics and important characteristics are passed to manufacturing.

[0051] As a further improvement of the present invention, in step S301, functional analysis is first carried out to determine the function of the process starting from the highest level and gradually entering the lowest agreed level of the analyzed process; then a process flow chart is formulated to represent the working conditions and mutual relationships of each process unit, as well as the logical sequence relationship between each process; finally, a component-process relationship matrix is ​​formulated to represent the relationship between component characteristics and process operations and processes.

[0052] As a further improvement of the present invention, in step S305, in the measure priority AP: S is the severity level of the process failure mode, O is the probability level of the process failure mode, and D is the difficulty level of detecting the process failure mode, wherein the calculation formula of RPN is RPN=S*O*D, and the larger the RPN value is, the greater the harmfulness of the process failure mode is; in step S306, all process improvement measures are formulated with the starting point of reducing the severity, probability of occurrence and difficulty level of detection of the process failure mode.

[0053] As a further improvement of the present invention, in step S307, after taking improvement measures for key / critical processes, predict or track whether the improvement measures are effective, and re-evaluate the S, O, D, RPN values ​​and AP after taking the improvement measures; in step S308, track the implementation status, optimize the D / PFMEA and key characteristics control of key parts, and optimize the D / PFMEA work and related key characteristics control of key parts based on the design, testing, installation test flight and operation of the product.

[0054] By means of the above scheme, the present invention has at least the following advantages:

[0055] 1. Ability to identify potential risks in advance: Through precision measurement, the possible design and process failure modes of airborne equipment can be accurately analyzed. For example, for the signal transmission module of airborne communication equipment, precision measurement can help determine the reasonable range of parameters such as signal strength and frequency, and discover factors that may cause signal transmission failures in advance, such as poor contact, component aging, and other potential problems in the design or manufacturing process, so as to take measures in advance to prevent failures.

[0056] 2. Improve product reliability: In airborne equipment, which has extremely high requirements for safety and stability, D / PFMEA, assisted by precision measurement, can conduct detailed analysis of the key performance indicators of the equipment. Taking the aircraft's navigation equipment as an example, by precisely measuring the measurement accuracy requirements of parameters such as altitude, speed, and position, possible failure modes can be optimized during the design and manufacturing stages, thereby effectively reducing the probability of equipment failure during actual flight and greatly improving product reliability.

[0057] 3. Optimize maintenance strategy: This working method can reasonably arrange maintenance plans and resource allocation based on the severity and frequency of equipment failure modes obtained through precise measurement. For example, for those airborne equipment components that are prone to failure and have serious consequences, maintenance spare parts can be prepared in advance and more frequent inspection plans can be formulated, thereby improving the pertinence and efficiency of maintenance and reducing maintenance costs and equipment downtime.

[0058] 4. Helps meet airworthiness requirements: In the aviation field, airborne equipment must meet strict airworthiness standards. The D / PFMEA working method based on precision measurement can provide detailed analysis data on the safety and reliability of the equipment, which serves as strong evidence of compliance with airworthiness requirements and helps the equipment pass airworthiness certification smoothly.

[0059] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention with accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0061] Figure 1It is a flow chart of an FMEA working method for airborne equipment oriented to key characteristic control of the present invention;

[0062] Figure 2 yes Figure 1 Schematic diagram of the process of step S1, DFMEA analysis;

[0063] Figure 3 yes Figure 1 Schematic diagram of the process of determining key parts and characteristics in step S2;

[0064] Figure 4 yes Figure 1 Schematic diagram of the process of step S3, PFMEA analysis. DETAILED DESCRIPTION

[0065] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0066] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, rather than all the embodiments. The components of the embodiment of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiment of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents the selected embodiment of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention.

[0067] Example:

[0068] 1. Explanation of DFMEA analysis, PFMEA analysis and key characteristic identification and control in the present invention:

[0069] 1. DFMEA analysis technology

[0070] DFMEA is to identify potential failure risks in advance during the design phase, rather than to remedy them afterwards. By systematically analyzing the weaknesses in product functions, material selection, structural design, etc., predicting failure modes (such as wear, fracture, performance degradation), and formulating improvement measures (such as redundant design, material optimization), the probability of product failure can be reduced from the source to avoid major losses during mass production or use. DFMEA uses a standardized analysis framework (such as structure tree, functional network, failure chain) to decompose the product system layer by layer and clarify the correlation between components. DFMEA requires cross-functional team collaboration (design, process, testing, quality, etc.), integrating professional knowledge from different fields, and through team collaboration, ensuring that risk analysis covers the entire product life cycle and improves the feasibility and reliability of design solutions.

[0071] 2. PFMEA analysis technology

[0072] PFMEA analyzes the failure modes and effects in the process. Process failures can include various situations of tolerance, assembly errors, unqualified heat treatment and surface treatment, and process fluctuations caused by environmental changes. Its purpose is to identify key process steps and formulate improvement measures based on the action priority (AP) and risk priority number (RPN) value of the process failure mode, based on the assumption that the designed product meets the design requirements, for the process failure modes, causes and all impacts on the product that may occur in each process during the production process, and to predict or track the reduction of RPN and AP levels after taking improvement measures, verify the effectiveness of improvement measures, and thus improve product quality and reliability.

[0073] 3. Key feature identification and control technology

[0074] Key characteristics identification and control technology plays a vital role in product quality management. Key characteristics refer to those characteristics that have a significant impact on product performance, safety and reliability. According to the degree of impact, key characteristics can be divided into critical characteristics and important characteristics. If key characteristics do not meet the requirements, it may cause the product to fail to complete the main task and endanger personal safety, while if important characteristics do not meet the requirements, it may cause the product to fail to complete the main task but will not endanger personal safety.

[0075] The identification of key characteristics is mainly carried out through design analysis, manufacturing process analysis, assembly and testing, flight testing and other links. Design analysis is to identify key characteristics by analyzing the impact of material properties, process requirements, interchangeability and coordination on product performance and quality. Manufacturing process analysis is to identify key characteristics that may affect product performance during the manufacturing process through methods such as PFMEA. Test and inspection analysis is to identify key characteristics that have a significant impact on product performance through test and inspection processes.

[0076] The control technology of key characteristics includes three aspects. One is FMEA work, which identifies possible failure modes in the design and production process through FMEA, evaluates their potential impact on use, and then analyzes the causes and formulates preventive measures to reduce the occurrence of failures. Another is dimensional chain analysis, which conducts dimensional chain analysis on the identified key characteristics, determines the key dimensional chains that affect these characteristics, and ensures the effectiveness of control measures. The last is quality control, which formulates targeted control measures, such as improving processes, strengthening inspections, optimizing designs, etc., and incorporates these measures into documents such as work instructions to ensure effective implementation in the production process.

[0077] 2. The main purpose of the present invention:

[0078] 1. FMEA can be generally divided into design FMEA (DFMEA) and process FMEA (PFMEA) according to the different use stages. PFMEA mainly aims at the possible failure modes, causes and all impacts on the product in each process step of the production process, and formulates improvement measures for the weak links of the process according to the risk of the failure mode, so as to improve the reliability of the product, assuming that the designed product can meet the design requirements. DFMEA includes functional FMEA, hardware FMEA and software FMEA. Different forms of FMEA will be used at various stages of the product life cycle, but the fundamental purpose is to discover various defects and weak links of the product from different angles, and take effective improvement and compensation measures to improve its reliability level. Functional FMEA, this method believes that each product can complete several functions, and functions can be classified by output. When using this method, the outputs are listed one by one, and their failure modes are analyzed. This method can usually be used when the composition of the product cannot be clearly determined (such as in the early stage of product development, the design of each component has not been completed, and a detailed component list, product schematic diagram and product assembly drawing cannot be obtained), or when the complexity of the product requires downward analysis from the initial agreed level, that is, "top-down" analysis. This method is relatively simple, but it is easy to miss some failure modes. Hardware FMEA lists each product in a table and analyzes all possible failure modes of the product and their impacts. This method is generally used when the product can be clearly determined according to the design drawings and other engineering design data. This analysis method is suitable for starting from the part level and then expanding to the system level, that is, bottom-up analysis, or analysis from any level to any direction. All products must use hardware FMEA. For newly developed products whose product composition cannot be clearly determined, functional FMEA can be carried out first, and then converted to hardware FMEA after determination. Hardware FMEA can be carried out directly for shelf products.

[0079] 2. Failure Mode and Effect Summary (FMES) is a method of summarizing the lower-level failure modes with the same impact in the FMEA analysis results, summing up their failure rates, and treating the impact as a failure mode of FMES to further analyze its possible impact on the upper-level system. FMES can be used as part of FMEA, where the analysis results are used to summarize the same impact of different failure modes on the system or equipment, treat the impact as a single point failure, and simplify the fault tree analysis by reducing the number of gates at the lowest level. FMES does not have to be analyzed separately and can be completed as part of FMEA. Therefore, it is recommended to complete FMES work while performing FMEA, and both are written in the same report.

[0080] 3. At the system level where the airborne equipment is located, through the implementation of complete functional, hardware and process FMEA work, the integrity and correctness of FMEA in the design and manufacturing process can be initially guaranteed. By identifying the reliability weaknesses of the equipment design, targeted corrective measures can be designed to improve the basic reliability of the equipment, and the equipment DFMEA and PFMEA can be organically combined to jointly improve the reliability level of the equipment.

[0081] 4. At the aircraft level where the airborne equipment is located, the establishment of the fault propagation chain and failure analysis research are carried out by combining cascade impact analysis and model-based reliability analysis methods, so that the main manufacturer can use FMEA as a starting point to identify the fault propagation path and comprehensively consider the cascading impact of concurrent failures after equipment failure on the system and aircraft. The failure mode identified in the design stage can be effectively corrected and prevented by design during the manufacturing and operation process, thereby maximizing the safety and reliability of the aircraft from the two perspectives of underlying equipment and system architecture design.

[0082] 3. The first embodiment of the present invention (such as Figure 1 to Figure 4 shown):

[0083] The airborne equipment FMEA working method of the present invention comprises the following steps in sequence:

[0084] Step S1, DFMEA analysis:

[0085] Step S101: define the analysis object, and define the level at which the analyzed product is located.

[0086] Step S102: product function analysis, analyzing the product functions and providing a product function definition.

[0087] Step S103: Draw a function and reliability block diagram. Draw a product function and reliability block diagram based on the product function definition and architecture.

[0088] Step S104, design failure mode analysis. For shelf products, the FMEA can be determined based on the previous product FMEA and operational failures, and the differences in the use environment can be analyzed. For newly developed products, analysis and prediction can be carried out based on the functional principles or structural characteristics of the product, or based on the failure modes that have occurred in products with similar functions and similar structures, the possible failure modes can be analyzed and determined. According to the functional description of the product, analyze failure modes such as complete loss of function, partial loss of function, abnormal function, functional error, non-instruction operation, etc., and then according to the hardware characteristics of the product, find all possible hardware failure modes in the requirements of the failure criteria, and correspond them with the functional failure modes to ensure that all functional failure modes have corresponding hardware failure modes. For the failure modes of commonly used components and parts, their failure modes can be determined from domestic and foreign standards and manuals.

[0089] Step S105, design failure cause analysis, find out the cause of the failure mode, and then take targeted and effective corrective measures to prevent or reduce the possibility of the failure mode. Combine engineering experience with failure physics theory to analyze the possible causes of each failure mode. Direct causes such as product design defects and manufacturing defects that lead to product functional failure or potential failure; indirect causes of product failure caused by external factors (such as failure of other products, use, environment and human factors, etc.); failure modes and failure causes should be correctly distinguished. Failure modes are generally observable forms of failure, while failure causes are caused by design defects, manufacturing defects or external factors.

[0090] Step S106, task phase / working mode definition, determine the task phase and working mode of the analyzed product. If the analyzed product has multiple task profiles, each task profile should be described separately; if each task profile of the analyzed product is composed of multiple task phases, and each task phase may have different working modes, then this situation needs to be explained or described. Each task phase / working mode needs to be considered one by one when conducting FMEA analysis.

[0091] Step S107, design failure impact analysis, failure impact is to find out the impact of each failure mode on the use, function, status, etc. of the product itself or other products, and analyze its severity. According to different severity categories, corrective measures design, key component identification and other work can be carried out. Failure impact analysis not only analyzes the impact of the failure mode on the same level of the product, but also analyzes the impact on higher-level products. Failure impacts are usually divided into local impacts (associated equipment), higher-level impacts (systems) and final impacts (aircraft level). When performing failure impact analysis, it is necessary to clarify that there is a certain relationship between failure modes and failure effects at different levels. During the analysis process, it is necessary to pay attention to the iterative relationship between different agreed levels to ensure the traceability of data at each level; and for products that adopt redundancy design, backup working mode design or failure detection and protection design, these design measures should not be considered in FMEA for the time being, and the final impact of the product failure mode should be directly analyzed. The above-mentioned design corrective measures have been taken for the product in the FMEA table.

[0092] Step S108, failure mode reliability data analysis, failure mode related reliability data in FMEA analysis including failure mode failure rate, frequency ratio and other reliability data acquisition mainly includes: route statistical data, reliability test data, relevant aviation manuals, such as EPRD, NPRD, GJB299, MIL-HDBK-217, FMD, etc., and public data for reference of other models.

[0093] Step S109, failure impact level analysis: in the FMEA analysis, the failure impact level needs to be defined. The failure impact level includes the hazard level and the severity category, which are filled in according to the level of the analysis object.

[0094] Hazard level: Before conducting a failure impact analysis, the hazard level of the failure mode should be defined. It is determined based on the degree of impact of the failure mode's final impact on the aircraft, occupants, and flight crew. This level is consistent with the functional failure state impact level defined in the safety FHA. This section only analyzes single-point failures, and the hazard level of the fault tree top event caused by a single-point failure is the hazard level of the failure mode.

[0095] Severity category: When conducting FMEA analysis on the initial agreed level, i.e., equipment / components, it is impossible to determine the overall impact of the product failure mode on the aircraft, which in turn makes it impossible to classify according to the safety FHA level. In this case, the impact of the failure mode on the initial agreed level (equipment / component) can be determined first, and the degree of this impact is defined as the severity category (or level). It should be noted that when conducting FMEA on the same product, the definition of the severity category should be consistent. Generally, the severity category information that needs to be filled in when the equipment supplier conducts equipment FMEA analysis is determined according to the final impact of each failure mode, that is, the degree of impact on the "initial agreed level".

[0096] Step S110, cascade impact analysis, in the process of conducting system hardware FMEA analysis, combined with the previous model FMEA development experience, it is necessary to consider the cascade analysis of failure impacts and the impact of failure propagation in the process of failure impact analysis to increase the accuracy of failure impact analysis and provide input for model cascade impact analysis. In the actual analysis, fill in the information such as the system, equipment, and specific failure modes in the equipment that provide input for the failure mode being analyzed.

[0097] Step S111, detection method analysis, detection method analysis is to analyze whether there is a detection method that can find the failure mode for each failure mode, so as to provide a basis for the failure detection and isolation design, maintenance and other work of the product. The detection method generally includes: visual inspection, in-situ detection, off-site detection, etc., and its means are such as built-in test (BIT), sound alarm device, etc., and the detection means are more detailed in the FMEA form. For those who do not have failure mode detection means, attention should be paid in the design. It should be noted that when carrying out the system hardware FMEA analysis, the indication and detection method of each failure mode are divided in detail, and the corresponding detection means, fault isolation level, indication and route troubleshooting guidance are determined to provide data input for the fault diagnosis design of the model. Specifically, it includes the indication / phenomenon of failure on the aircraft (used to evaluate the ability to inform relevant users of fault information, and the cockpit effect (FDE) associated with the failure mode, the onboard maintenance system (OMS) message and other perceptible fault characterization phenomena should be given), and failure detection analysis (whether it can be detected through BIT or detected by external testing means, etc.).

[0098] Step S112, corrective measures. Corrective measures are an important part of FMEA work. During the use and maintenance of the product, once a certain failure mode occurs, the most appropriate operational measures should be taken to eliminate or reduce the impact of the failure, thereby improving the reliability of the product. Corrective measures are divided into design improvement measures and use and maintenance measures. The main contents of design improvement and use compensation measures are: design improvement measures: when a product fails, it should be considered whether there are redundant equipment that can continue to work; safety or insurance devices (such as monitoring and alarm devices); alternative working methods (such as spare or auxiliary equipment); design improvements that can eliminate or reduce the impact of failures (such as preferred components, thermal design, derating design, etc.); use and maintenance measures: in order to avoid or prevent the occurrence of failures as much as possible, the use and maintenance measures specified in the use and maintenance procedures. Once a certain failure occurs, the most appropriate remedial measures that the operator should take, etc. In the system hardware FMEA, the use and maintenance measures are also subdivided into crew corrective measures and route maintenance personnel troubleshooting guidelines (including confirmation of the existence of the fault and subsequent maintenance work guidelines to help route maintenance personnel troubleshoot the fault, confirmation measures for the occurrence of the fault, maintenance measures for the fault, and troubleshooting confirmation measures).

[0099] Step S113, FMES analysis. The analyst checks the consistency of the failure effects of the FMEA analysis results (i.e., whether the same words are always used to describe the same failure effects, and whether different words related to failure effects always represent different failures). Pay special attention to this check when performing system-level FMES. Enter the failure effects from FMEA into the "Failure Mode" column of the FMES table; identify all failure modes with the same failure effects, add up their respective failure rates, and fill the calculated failure rate into the "Failure Mode Failure Rate" column; fill the failure mode's impact on the next higher level, the symptoms of this failure, and the related flight / mission phases into the FMES related table column; mark the references to each failure mode in the FMEA and the corresponding failure rate in the "Failure Cause" column.

[0100] Step S114, fill in the FMEA and FMES analysis tables. The FMEA table includes analysis object information (such as function name, function description, etc.), FMEA code, failure mode, failure cause, failure impact (including local, higher level, and final impact), failure rate related data (such as single product failure rate, failure mode frequency ratio, exposure time, failure mode occurrence probability), impact level (hazard level, severity category), detection method (such as various detection methods), corrective measures (use measures, maintenance measures), and the contents of the table filled in different FMEA analysis methods at different levels are different. The FMES table mainly includes FMES number, failure mode, failure rate, task stage information, failure symptoms, failure cause and related information.

[0101] Step S2: Determination of key components and characteristics:

[0102] Step S201, determine the key parts and important parts. The key parts are those whose failure may lead to catastrophic consequences, such as aircraft crashes or casualties. They are generally the first- and second-order minimum cut set equipment in the safety FHA for catastrophic failure states, and the first-order minimum cut set equipment for dangerous failure states. Important parts are those whose failure may lead to serious but not necessarily catastrophic consequences, such as loss of system function or performance degradation. They are generally the equipment in the second-order minimum cut set for dangerous failure states, the equipment in the first-order minimum cut set for major failure states, and the equipment in the first- and second-order minimum cut set for failure states that lead to flight interruption, and the equipment in the first-order minimum cut set for failure states that lead to dispatch interruption.

[0103] Step S202, identify the key characteristics of key parts. The key characteristics and important characteristics of key parts and important parts have a significant impact on the function, service life, assembly, size and manufacturability of the final product, and these performances will eventually affect the failure probability and thus affect the safety of the aircraft. First, clarify the core functions (such as navigation, communication) and auxiliary functions (such as data recording) of the equipment, and evaluate their accuracy, response time and reliability; then, based on FHA and PSSA, determine the relevant DFMEA failure modes of key parts in catastrophic, dangerous, major, flight interruption and dispatch interruption failure states, and correspond to the core functions of the equipment to determine the key characteristics identified in the design process of the equipment; finally, in the manufacturing process, identify the manufacturing and assembly process procedures of the key characteristics of the equipment through PFMEA.

[0104] Step S203, carry out the transfer of key characteristics in D / PFMEA. In DFMEA, incorrect design and incorrect definition may cause failure causes, leading to product function failure. In PFMEA, due to errors in the manufacturing process, failure modes are generated, and the expected functions and requirements are not met. The failure modes in PFMEA correspond to the failure causes in DFMEA, so PFMEA defines the failure modes in PFMEA based on the failure causes (product characteristics) in DFMEA. Therefore, it is necessary to sort out the failure causes related to manufacturing in DFMEA as the input of PFMEA; on the other hand, how to transfer these key characteristics and important characteristics to manufacturing is also very important. PFMEA includes manufacturing process PFMEA and assembly process PFMEA. Manufacturing process PFMEA is mainly completed by equipment manufacturers, and assembly process PFMEA is mainly completed by aircraft manufacturers.

[0105] Step S3: Conduct PFMEA analysis:

[0106] Step S301, system definition, first carry out functional analysis, determine the function of the process should start from the highest level, and gradually enter the lowest agreed level of the analyzed process. Develop a process flow chart to show the working conditions and mutual relationship of each process unit, as well as the logical sequence relationship between each process. Develop a component-process relationship matrix to show the relationship between component characteristics and process operations and processes. Its purpose is to comprehensively consider the direct or indirect relationship between all characteristics of the analyzed component and each process in the process operation.

[0107] Step S302, process failure mode analysis, failure mode refers to defects that cannot meet process requirements and / or design intent. It may be the cause of the failure mode of the next (downstream) process, or it may be the consequence of the failure of the previous (upstream) process. In PFMEA, it is assumed that the parts / materials provided are qualified. Generally, in PFMEA, defects in product design are not considered. In engineering applications, the failure mode can be determined by referring to the process failure modes of similar products or based on engineering experience. Typical process failure modes include: bending, deformation, cracks, fractures, burrs, leaks, size tolerance, position tolerance, shape tolerance, too smooth surface, no labeling, etc.

[0108] Step S303, process failure cause analysis, analyze the causes of process failure modes, such as excessive torque, cold welding, weak bonding, tool wear, missing parts, wrong parts, improper installation, positioner wear, holes, incorrect machine settings, no lubrication, etc.

[0109] Step S304, process failure impact analysis, failure impact refers to the impact of process failure mode on the next process, subsequent processes, and / or aircraft level, such as inability to remove, mismatch, inability to install, inability to connect, inability to match, inability to surface process, damage to equipment, harm to operators, excessive noise, excessive vibration, excessive loss, water leakage, oil leakage, surface defects, unplanned maintenance, abandonment, etc.

[0110] Step S305, AP and RPN analysis, the measure priority (AP) is to classify the 1000 combinations of S, O, and D, and reflect the priority of the measures to be taken according to the evaluation of these combinations, which are divided into three types: H (high), M (medium), and L (low). The risk priority number (RPN) reflects the comprehensive measure of the possibility of the occurrence of the process failure mode and the severity of its consequences. The larger the RPN value, the greater the harmfulness of the process failure mode. The calculation formula of RPN is shown in formula (1). AP and RPN can be used to screen key processes and evaluate the effectiveness of measures.

[0111] RPN=S×O×D.............(1)

[0112] Process failure mode severity level (S) analysis: The severity level of a process failure mode refers to the degree of influence of the process on a certain failure mode, and is an evaluation parameter for the severity of the consequences of the influence. The reduction of the severity level can only be achieved through design changes or redesign.

[0113] Process failure mode occurrence probability level (O) analysis: The process failure mode occurrence probability level refers to the possibility of a certain process failure mode occurring.

[0114] Process failure mode detection difficulty level (D) analysis: The process failure mode detection difficulty level is an evaluation parameter for the possibility of using current detection methods to find the failure cause / mechanism or subsequent failure mode before the parts leave the manufacturing process or assembly station. It is an evaluation of the ability of the current detection method to detect each failure mode.

[0115] Step S306: Formulate improvement measures. Improvement measures refer to all process improvement measures that are based on reducing the severity, probability of occurrence and difficulty of detection of process failure modes. Failure modes with a measure priority (AP) of H (high) are key processes. All key processes need to combine actual process level, management level and cost factors to provide preventive / improvement measures in terms of process design or process control.

[0116] Step S307, analysis of AP and RPN after improvement. After taking improvement measures for key / critical processes, it is necessary to predict or track whether the improvement measures are effective, and re-evaluate the S, O, D, RPN values ​​and AP after taking the improvement measures. AP needs to be reduced to M or L, or it can be proved that the current measures are appropriate; if both are 9-10, RPN is required to be reduced to below 100. If the improvement measures are effective, the analysis ends; if not, RPN and AP analysis is repeated until the RPN and AP of all process failure modes meet the requirements or there are no corrective measures.

[0117] Step S308: Track the implementation status, optimize the D / PFMEA and key characteristics control of key parts, optimize the D / PFMEA work and the related key characteristics control of key parts according to the product design, testing, installation test flight and operation status, and improve the reliability and quality stability of the product.

[0118] Fourth, the implementation principle of the present invention is mainly:

[0119] 1. To carry out FMEA, you first need to define the system to be analyzed. The definition of the analysis object can be summarized as the functional analysis of the product and drawing of the block diagram. The functional analysis of the product includes the various tasks and completion time of the product, each task stage / working mode and its environmental profile, determining the functional relationship of the product, and determining the failure criteria of the product and its components; drawing the block diagram includes drawing the functional block diagram and reliability block diagram of the product.

[0120] 2. During the PFMEA process, AP and RPN can be used to screen key processes and evaluate the effectiveness of measures. RPN reflects the comprehensive measure of the possibility of process failure modes and the severity of their consequences, among which product impact and the corresponding severity of product impact need to refer to DFMEA. The action priority (AP) is to classify 1,000 combinations of S, O, and D. According to the evaluation of these combinations, it reflects the priority of measures to be taken, which are divided into three types: H (high), M (medium), and L (low). According to E-C942JY069, the failure mode with an action priority (AP) of H (high) is a key process, and all key processes need to formulate improvement measures; the key process must determine an applicable improvement detection or prevention measure to reduce the level to M or L, or prove that the current measures are appropriate; if the severity (S) is 9-10 at the same time, the risk priority number (RPN) must be reduced to below 100.

[0121] 3. When conducting system hardware FMEA analysis, the indications and detection methods of each failure mode are divided in detail, and the corresponding detection means, fault isolation level, indications and route troubleshooting guidelines are determined to provide data input for the fault diagnosis design of the model. Specifically, it includes the indications / phenomena of failure on the aircraft (used to evaluate the ability to inform relevant users of fault information, and the cockpit effects (FDE) associated with the failure mode, onboard maintenance system (OMS) messages and other perceptible fault characterization phenomena should be given), failure detection analysis (whether it can be detected through BIT or through external testing means, etc.).

[0122] The present invention transfers the failure causes related to manufacturing identified in DFMEA to PFMEA, considers the product impact of DFMEA and the corresponding severity of the product impact, and identifies the process procedures related to manufacturing in combination with the performance indicators, process conditions, installation conditions, environmental conditions, maintenance conditions and other characteristics of key parts, and finally carries out PFMEA of key parts, further identifies the key process procedures through AP and RPN, and carries out statistical process control on them, so as to realize the comprehensive and effective transmission of key part information to manufacturing.

[0123] The present invention first identifies the manufacturing-related reasons in the DFMEA of the key parts, and then identifies the key process characteristics in the product manufacturing process in combination with the key characteristics and important characteristics of the key parts. After that, the key process procedures are further controlled based on AP and RPN by conducting PFMEA of the key parts.

[0124] The present invention carries out calculation and analysis of the failure mode failure rate and frequency ratio of DFMEA, replaces the traditional subjective scoring analysis method based on operation data, manual data, data of similar models, etc., and carries out quantitative analysis of the failure mode failure rate of equipment based on engineering design, laying a solid foundation for the safety and reliability work of civil aircraft.

[0125] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implying the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0126] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, it can be a mechanical connection, it can be an electrical connection, it can be a direct connection, it can be indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0127] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the technical principles of the present invention, and these improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A FMEA working method for airborne equipment oriented to key characteristic control, characterized by: The following steps are included in sequence: Step S1, DFMEA analysis: Step S101, analysis object definition; Step S102: product function analysis; Step S103, drawing a function and reliability block diagram; Step S104, design failure mode analysis; Step S105, design failure cause analysis; Step S106, task phase / working mode definition; Step S107: design failure impact analysis; Step S108, failure mode reliability data analysis; Step S109, failure impact level analysis; Step S110: cascade impact analysis; Step S111, detection method analysis; Step S112: corrective measures; Step S113, FMES analysis; Step S114, fill in FMEA and FMES analysis tables; Step S2: Determination of key components and characteristics: Step S201, determine key parts and important parts; Step S202, identifying the critical characteristics of the critical parts; Step S203, carrying out the transmission of key characteristics in D / PFMEA; Step S3: PFMEA analysis: Step S301, system definition; Step S302: process failure mode analysis; Step S303, process failure cause analysis; Step S304: process failure impact analysis; Step S305: AP and RPN analysis; Step S306: Formulate improvement measures; Step S307: Improved AP and RPN analysis; Step S308: Track the implementation status and optimize the D / PFMEA and key characteristic management of key parts.

2. The FMEA working method for airborne equipment oriented to key characteristic control according to claim 1, characterized in that: In step S101, the level of the analyzed product is defined; in step S102, the functions of the product are analyzed and a product function definition is given; in step S103, a product function and reliability block diagram is drawn based on the product function definition and architecture.

3. The FMEA working method for airborne equipment oriented to key characteristic control according to claim 1, characterized in that: In step S104, failure modes are analyzed based on the functional description of the product, and then based on the hardware characteristics of the product, all hardware failure modes are found in the requirements of the failure criteria, and corresponded with the functional failure modes to ensure that all functional failure modes have corresponding hardware failure modes; in step S105, the causes of the failure modes are found, including direct causes such as product design defects and manufacturing defects that lead to functional failure or potential failure of the product, and indirect causes of product failure caused by external factors; in step S106, the task stage / working mode of the analyzed product is determined, and each task stage / working mode needs to be considered one by one.

4. The FMEA working method for airborne equipment oriented to key characteristic control according to claim 1, characterized in that: In step S107, the influence of each failure mode on the use, function and status of the product itself or other products is found, and its severity is analyzed; in step S108, failure mode related reliability data including but not limited to failure mode failure rate and frequency ratio reliability data are obtained; in step S109, the failure impact level includes hazard level and severity category, which are filled in according to the level of the analysis object.

5. The FMEA working method for airborne equipment oriented to key characteristic control according to claim 1, characterized in that: In step S111, the detection methods include but are not limited to visual inspection, on-site detection and off-site detection; in step S112, the corrective measures are divided into design improvement measures and usage maintenance measures.

6. The FMEA working method for airborne equipment oriented to key characteristic control according to claim 1, characterized in that: In step S113, the analyst checks the consistency of the failure effects of the FMEA analysis results; in step S114, the FMEA form includes but is not limited to analysis object information, FMEA code, failure mode, failure cause, failure effect, failure rate related data, impact level, detection method and corrective measures; the FMES form includes but is not limited to FMES number, failure mode, failure rate, task stage information, failure symptoms and failure causes.

7. The FMEA working method for airborne equipment oriented to key characteristic control according to claim 1, characterized in that: In step S202, the core functions and auxiliary functions of the equipment are first identified, and their accuracy, response time and reliability are evaluated; then, based on FHA and PSSA, the relevant DFMEA failure modes of key parts in catastrophic, dangerous, major, flight interruption and dispatch interruption failure states are determined, and corresponded with the core functions of the equipment to determine the key characteristics of the equipment identified during the design process; finally, in the manufacturing process, the manufacturing and assembly process procedures of the key characteristics related to the equipment are identified through PFMEA; in step S203, the failure causes related to manufacturing in DFMEA are sorted out as inputs to PFMEA, and then its key characteristics and important characteristics are passed to manufacturing.

8. The FMEA working method for airborne equipment oriented to key characteristic control according to claim 1, characterized in that: In step S301, functional analysis is first carried out to determine the function of the process starting from the highest level and gradually entering the lowest agreed level of the analyzed process; then a process flow chart is formulated to represent the working conditions and mutual relationships of each process unit, as well as the logical sequence relationship between each process; finally, a component-process relationship matrix is ​​formulated to represent the relationship between component characteristics and process operations and processes.

9. The FMEA working method for airborne equipment oriented to key characteristic control according to claim 1, characterized in that: In the step S305, in the measure priority AP: S is the severity level of the process failure mode, O is the probability level of the process failure mode, and D is the difficulty level of the process failure mode detection, wherein the calculation formula of RPN is RPN=S*O*D, and the larger the RPN value, the greater the harmfulness of the process failure mode; in the step S306, all process improvement measures are formulated with the starting point of reducing the severity, probability of occurrence and difficulty level of the process failure mode.

10. The FMEA working method for airborne equipment oriented to key characteristic control according to claim 1, characterized in that: In step S307, after taking improvement measures for key / critical processes, predict or track whether the improvement measures are effective, and re-evaluate the S, O, D, RPN values ​​and AP after taking the improvement measures; in step S308, track the implementation status, optimize the D / PFMEA and key characteristics control of key parts, and optimize the D / PFMEA work and related key characteristics control of key parts based on the design, testing, installation test flight and operation of the product.

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