A method for allocating quantitative indicators of aircraft engine safety based on functional failure modes

Abstract

The present invention discloses a method for allocating quantitative safety indicators of aircraft engines based on functional failure modes, comprising the following steps performed in sequence: step 1, determining harmful consequence events at the engine level based on a functional hazard analysis method; step 2, determining the expected probability of occurrence of each harmful consequence event of the engine; step 3, determining the quantitative safety indicators of the engine systems / components; the aircraft engine safety indicator decomposition method of the present invention can effectively allocate the total probability of harmful consequences borne by the engine to components and systems, clarify the safety design requirements of components and systems, ensure the correctness of indicator allocation, and serve as the basis for safety design of engine components and systems. The method has strong engineering application value.

Description

Technical Field

[0001] The present invention relates to a method for allocating quantitative indicators of aircraft engine safety based on a functional failure mode, and belongs to the technical field of aircraft engines. Background Art

[0002] As the core power source of aircraft, the safety of aircraft engines has always attracted considerable attention. The quantitative safety requirement for aircraft engines during development is based on the total probability of serious aircraft loss due to engine failure. It is inappropriate to use the total probability of hazardous consequences as the basis for safety design during the development of components, systems, and accessories. Therefore, to clarify the quantitative safety requirements for engine components and systems, it is necessary to allocate engine safety quantitative indicators. This allows for clear safety design requirements for components, systems, and accessories during design, enabling appropriate safety design, verification, and assessment to ensure that safety indicators at different levels meet requirements.

[0003] Currently, fault trees are commonly used to allocate quantitative indicators for engine safety. Fault tree analysis is used to establish an allocation model, identifying all the fault events that lead to top events. Using the proportional method, indicators are then allocated to relevant components and systems. However, at the design stage, only the functional architecture of an aircraft engine is clearly defined, making it difficult to ensure the accuracy of indicator allocation using fault trees. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a method for allocating quantitative indicators of aircraft engine safety based on functional failure modes.

[0005] The present invention is achieved through the following technical solutions.

[0006] The present invention provides a method for allocating quantitative indicators of aircraft engine safety based on functional failure modes, comprising the following steps performed in sequence:

[0007] Step 1: Determine the hazardous consequence events at the engine level based on the functional hazard analysis method;

[0008] Step 2: Determine the expected probability of occurrence of each engine hazardous consequence event;

[0009] Step 3: Determine the quantitative safety indicators of engine systems / components;

[0010] The first step of determining the hazardous consequence events at the engine level based on the functional hazard analysis method is divided into two sub-steps: determining the engine hazardous functional failure mode and determining each hazardous consequence event of the engine.

[0011] The steps for determining the dangerous functional failure mode of the engine are as follows: it is necessary to determine the events that cause harmful consequences at the aircraft engine whole-machine level to ensure the feasibility of the safety quantitative indicators undertaken by the assigned objects; in the planning stage, the functions and definitions of the engine whole-machine level, system level and component level have been clearly defined, and the functional failure status of the engine whole machine and system / component is identified through the functional hazard analysis method to determine the dangerous state and severity level caused by the functional failure.

[0012] The steps of determining each hazardous consequence event of the engine are as follows: obtaining Class I functional failure modes of hazard severity level through functional hazard analysis, and classifying or merging the functional failure modes based on the mapping relationship between the impact consequences of the engine and the aircraft and the functional failure modes.

[0013] The step of determining the expected probability of occurrence of each hazardous consequence event of the engine is as follows: the indicator allocation of the hazardous consequence event is carried out based on the functional failure mode identified by the functional hazard analysis, and is proportionally allocated according to the number of hazardous functional failure modes contained in the hazardous event.

[0014] The specific expression of the engine hazardous consequences is:

[0015]

[0016] Where:

[0017] P(T)——total probability of engine hazardous consequences;

[0018] P(A i )——the expected probability of occurrence of the i-th harmful consequence event;

[0019] — the number of hazardous functional failure modes included in the i-th hazardous consequence event;

[0020] Among them, 10% represents the indicator margin coefficient, which can be adjusted appropriately.

[0021] The steps for determining the safety quantitative index of the engine system / component are as follows:

[0022] The quantitative safety indicators of components are developed based on the functional failure modes identified by the functional hazard analysis and are allocated proportionally according to the number of dangerous functional failure modes of the system / component involved in the hazardous event.

[0023] The specific expression for determining the safety quantitative index of the engine system / component is:

[0024]

[0025] Where:

[0026] P(B j )——the expected failure probability of the jth system / component in the i-th hazardous consequence;

[0027] P(A i )—the expected probability of occurrence of the i-th harmful consequence event;

[0028] — the number of dangerous function failure modes of the jth system / component in the i-th hazardous consequence;

[0029] ——The number of all dangerous functional failure modes of the i-th hazardous consequence event.

[0030] Among them, 10% represents the indicator margin coefficient, which can be adjusted appropriately.

[0031] The aviation engine safety index decomposition method proposed in this invention can effectively allocate the total probability of hazardous consequences borne by the engine to components and systems, clarify the safety design requirements of components and systems, ensure the correctness of index allocation, and serve as the basis for safety design of engine components and systems. This method has strong engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic flow diagram of the steps of the method of the present invention; DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described below, but the scope of protection claimed is not limited to the description.

[0034] refer to Figure 1 The present application provides a method for allocating quantitative indicators of aircraft engine safety based on functional failure modes, including the following steps:

[0035] 1. Determine the hazardous consequence events at the engine level based on the functional hazard analysis method

[0036] 1.1 Determine the engine's dangerous functional failure mode

[0037] To ensure the achievement of quantitative safety indicators for aircraft engines, it is first necessary to identify events that could cause hazardous consequences at the aircraft engine level, ensuring the achievability of the assigned safety indicators. During the planning phase, the functions and definitions of the aircraft, system, and component levels were clearly defined. Functional hazard analysis was used to identify functional failure states for the entire engine, systems, and components, determining the hazardous states and severity levels resulting from these failures. This resulted in a table of hazardous engine functional failure modes (see Table 1).

[0038] Table 1 Engine dangerous function failure mode table (example)

[0039]

[0040] 1.2 Determine the harmful consequences of engine events

[0041] Functional failure modes of Class I hazard severity level are obtained through functional hazard analysis. Based on the mapping relationship between the impact consequences of the engine and aircraft and the functional failure modes, the functional failure modes are classified or merged to form a table of engine-level hazardous consequence events, see Table 2.

[0042] Table 2 Engine-level hazardous consequence event table (example)

[0043]

[0044] 2. Determine the expected probability of occurrence of each engine hazardous consequence event

[0045] The indicator allocation for hazardous consequence events is based on the functional failure modes identified by the functional hazard analysis, and is allocated proportionally according to the number of hazardous functional failure modes contained in the hazardous event. That is, the more hazardous functional failure modes a hazardous event contains, the higher the proportion of its indicator in the overall machine indicator.

[0046] The specific expression is:

[0047]

[0048] Where:

[0049] P(T)——total probability of engine hazardous consequences;

[0050] P(A i )——the expected probability of occurrence of the i-th harmful consequence event;

[0051] ——The number of hazardous functional failure modes included in the i-th hazardous consequence event.

[0052] Among them, 10% represents the indicator margin coefficient, which can be adjusted appropriately.

[0053] 3. Determine the quantitative safety indicators of engine systems / components

[0054] The quantitative safety indicators of engine systems / components are also developed based on the functional failure modes identified by functional hazard analysis, and are distributed proportionally according to the number of dangerous functional failure modes of the systems / components contained in the hazardous events. That is, the more dangerous functional failure modes of the systems / components, the higher the proportion of their indicators in the overall machine-level hazardous event indicators.

[0055] The specific expression is:

[0056]

[0057] Where:

[0058] P(B j )——the expected failure probability of the jth system / component in the i-th hazardous consequence;

[0059] P(A i )—the expected probability of occurrence of the i-th harmful consequence event;

[0060] — the number of dangerous function failure modes of the jth system / component in the i-th hazardous consequence;

[0061] ——The number of all dangerous functional failure modes of the i-th hazardous consequence event.

[0062] Among them, 10% represents the indicator margin coefficient, which can be adjusted appropriately.

[0063] The beneficial technical effect of the present invention is that the aviation engine safety index decomposition method proposed in the present invention can effectively allocate the total probability of hazardous consequences borne by the engine to components and systems, clarify the safety design requirements of components and systems, ensure the correctness of index allocation, and serve as the basis for safety design of engine components and systems. This method has strong engineering application value.

[0064] The safety outline of a certain type of aircraft engine stipulates that the probability of a catastrophic accident (serious loss of aircraft) caused by engine failure shall not exceed 2×10 -6 / working hours is an actual example. The steps to determine the hazardous consequence events and expected probability of occurrence of a certain type of engine, as well as the safety indicators of the system / component are as follows:

[0065] 1. Determine the hazardous consequence events at the engine level based on the functional hazard analysis method

[0066] After a certain type of aircraft engine undergoes functional hazard analysis, the functional failure status of the engine as a whole and its systems / components is identified to form a Class I functional failure mode table for the engine hazard severity level. Combined with the mapping relationship between the impact consequences of the engine and aircraft and the functional failure modes, the functional failure modes are classified or merged to form engine-level hazardous consequence events.

[0067] A total of 10 engine hazardous consequence events were finally identified.

[0068] a) Fire;

[0069] b) non-inclusive;

[0070] c) Failure of the engine mounting joint leads to accidental engine disconnection;

[0071] d) Exceeding the specified limit load;

[0072] e) The engine loses the ability to stop;

[0073] f) The engine is in an uncontrollable high thrust state;

[0074] g) Engine throttle failure;

[0075] h) The cockpit bleed air affects the pilot's working ability;

[0076] i) Insufficient engine thrust during takeoff or escape;

[0077] j) The engine air start is unsuccessful.

[0078] 2. Determine the expected probability of occurrence of each engine hazardous consequence event

[0079] Based on the hazardous consequence events determined for a certain type of aircraft engine, the total failure rate of the engine's hazardous consequences is allocated to each hazardous consequence event according to formula (1). The expected probability of occurrence of each hazardous consequence event is shown in Table 3.

[0080] Table 3 Safety indicators of various hazardous consequences of engines

[0081]

[0082]

[0083] 3. Determine the expected probability of hazardous consequences of engine systems / components

[0084] Based on the expected probability of each hazardous consequence of the engine determined in Table 3, the expected probability of each hazardous consequence is allocated to the engine system / component according to formula (2). The quantitative safety indicators of the engine system / component are shown in Table 4.

[0085] Table 4 Quantitative indicators of engine system / component safety

[0086]

[0087]

[0088] By integrating the data in Table 4, the expected probability of dangerous consequences of engine components and systems is obtained in Table 5.

[0089] Table 5 Expected probability of dangerous consequences of system / component

[0090]

[0091]

Claims

1. A method for allocating quantitative indicators of aircraft engine safety based on functional failure modes, characterized in that: The method includes the following steps: Step 1: Determine the hazardous consequence events at the engine level based on the functional hazard analysis method; Step 2: Determine the expected probability of occurrence of each engine hazardous consequence event; Step 3: Determine the quantitative safety indicators of engine systems / components; The step of determining the safety quantitative index of the engine system / component is as follows: the safety quantitative index of the engine system / component is developed based on the functional failure modes identified by the functional hazard analysis, and is allocated proportionally according to the number of dangerous functional failure modes of the system / component included in the hazardous event; The specific expression for determining the safety quantitative index of the engine system / component is: Where: P(B j )——the expected failure probability of the jth system / component in the i-th hazardous consequence; P(A i )—the expected probability of occurrence of the i-th harmful consequence event; — the number of dangerous function failure modes of the jth system / component in the i-th hazardous consequence; — the number of all dangerous functional failure modes of the i-th hazardous consequence event; 10% represents the indicator margin coefficient.

2. The method for allocating quantitative indicators of aircraft engine safety based on functional failure modes according to claim 1, characterized in that: The first step of determining the hazardous consequence events at the engine level based on the functional hazard analysis method is divided into two sub-steps: determining the engine hazardous functional failure mode and determining each hazardous consequence event of the engine.

3. The method for allocating quantitative indicators of aircraft engine safety based on functional failure modes according to claim 2, characterized in that: The steps for determining the dangerous functional failure mode of the engine are as follows: it is necessary to determine the events that cause harmful consequences at the aircraft engine whole-machine level to ensure the feasibility of the safety quantitative indicators undertaken by the assigned objects; in the planning stage, the functions and definitions of the engine whole-machine level, system level and component level have been clearly defined, and the functional failure status of the engine whole machine and system / component is identified through the functional hazard analysis method to determine the dangerous state and severity level caused by the functional failure.

4. The method for allocating quantitative indicators of aircraft engine safety based on functional failure modes according to claim 2, characterized in that: The steps of determining each hazardous consequence event of the engine are as follows: obtaining Class I functional failure modes of hazard severity level through functional hazard analysis, and classifying or merging the functional failure modes based on the mapping relationship between the impact consequences of the engine and the aircraft and the functional failure modes.

5. The method for allocating quantitative indicators of aircraft engine safety based on functional failure modes according to claim 1, characterized in that: The step of determining the expected probability of occurrence of each hazardous consequence event of the engine is as follows: the indicator allocation of the hazardous consequence event is carried out based on the functional failure mode identified by the functional hazard analysis, and is proportionally allocated according to the number of hazardous functional failure modes contained in the hazardous event.

6. The method for allocating quantitative indicators of aircraft engine safety based on functional failure modes according to claim 5, characterized in that: The specific expression of the engine hazardous consequences is: Where: P(T)——total probability of engine hazardous consequences; P(A i )——the expected probability of occurrence of the i-th harmful consequence event; — the number of hazardous functional failure modes included in the i-th hazardous consequence event; 10% represents the indicator margin coefficient.

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