What is the Fault Tree Analysis?

Fault tree analysis (FTA) is a deductive failure analysis method from top to bottom, which uses Brin logic to combine low order events to analyze the states that do not want to appear in the system. Fault tree analysis is mainly used in the field of safety engineering and reliability engineering to understand the causes of system failure and to find the best way to reduce the risk or to confirm the incidence of a safety accident or a specific system failure. Fault tree analysis is also used in aerospace, nuclear power, chemical processes, pharmaceutical, petrochemical and other high-risk industries, as well as in other areas of risk identification, such as failure of social service systems. Fault tree analysis is also used in software engineering, in debugging, and is related to the technology of eliminating the cause of the error.

In the aerospace field, the broader term "system failure state" is used to describe the fault tree between the state that does not want to appear at the bottom and the failure event at the top. These states are classified according to the severity of their results. Results the most serious state needs the most extensive fault tree analysis to deal with. Such "system failure states" and their classification were previously addressed by functional hazard analysis.

What is the use of the Fault Tree Analysis?

• Understand the relationship between the top event and the state that does not want to appear below.

• The degree of conformity of the display system to the safety / reliability specifications of the system.

• Prioritize the causes of the top event: establish a list of key equipment/parts/events for different important measurements.

• Monitoring and controlling the security performance of complex systems.

• Minimize and optimize resource requirements.

• Assist in system design. Fault tree analysis can be used as a design tool to create output or lower-level module requirements.

• Diagnostic tools can be used to identify and correct the cause of the top event, helping to create diagnostic manuals or diagnostic procedures.

The history of the Fault Tree Analysis.

The fault tree analysis (FTA) was first developed by the Bell Labs H.A.Watson, First because the U.S. Air Force commissioned ICBM 526, An evaluation of the launch control system for the Yiyong-1 ICBM (ICBM) is required. Then fault tree analysis began to become a tool for reliability analysts to carry out failure analysis. A study on the launch control security of a military-type ICBM in 1962, First published using fault tree analysis techniques, From 1963 to 1964, Boeing and Avco began to apply fault tree analysis to the complete system of the Volunteer II. Sponsored by Boeing and the University of Washington in 1965, At the system security seminar in Seattle, The related techniques of fault tree analysis are widely reported. Boeing began to use fault tree analysis in the design of civil aviation aircraft in 1966.

Later, the U.S. military's Picatini Arsenal began to use fault tree analysis in lead applications in the 1960s and 1970s. Army Equipment Command began integrating fault tree analysis into the Reliability Design Engineering Design Manual (Engineering Design Handbook on Design for Reliability) in the 1976s. The reliability analysis center of the roman laboratory and the subsequent organization under the u.s. defense technology information center have published documents for fault tree analysis and reliability block diagrams since the 1960s. MIL-HDBK-338B have more recent references.

The United States Federal Aviation Administration (FAA) issued 14 CFR25.1309 of amendments in the 35 FR 5665(1970-04-08) of the Federal Gazette in 1970, It is aimed at the airworthiness of transport aircraft. This revision adopts the failure probability criterion for aircraft systems and equipment, Therefore, civil aviation operators began to use fault tree analysis. FAA issued Order 8040.4, in 1998 A risk management policy, including hazard analysis, Including a number of key activities following the certification of aircraft, Including air traffic control and modernization of the U.S. national airspace system, The Federal Aviation Administration later published a FAA system security manual (FAA System Safety Handbook), It describes a number of formal hazard analysis methods, also includes the use of FTA.

In the early days of the Apollo program in the United States, an analysis was made of the possible probability of sending astronauts to the moon and returning safely to Earth. Based on some risk (or reliability) calculations, the chances of success are unacceptably low. Therefore NASA there is no subsequent quantitative analysis or reliability analysis, only failure mode and impact analysis and other qualitative system security assessment tools, until the Challenger event. Then NASA experienced the importance of fault tree analysis and probability risk assessment (PRA) in system safety and reliability analysis, and began to be widely used. Later, fault tree analysis became one of the most important system reliability and safety analysis techniques.

For the nuclear power industry, the United States Nuclear Energy Regulatory Commission began using probabilistic risk assessments (PRA), including fault tree analysis, in 1975, and significantly expanded the study of probabilistic risk assessment after the San Mile Island nuclear leakage accident in 1979. Finally, the United States Nuclear Energy Regulatory Commission published in 1981 NRC Fault Tree Handbook NUREG–0492, also enforced the use of probabilistic risk assessment techniques within the jurisdiction of the Nuclear Energy Regulatory Commission.

The Occupational Safety and Health Administration of the United States Department of Labor (OSHA) issued a federal bulletin 57 in 1992 after the Bhopal incident in 1984 and the Alpha rig explosion in 1988 FR 6356(1992-02-24), which referred to the process safety management (PSM) standard occupational safety and health administration program safety management system in 19 CFR 1910.119 as a feasible approach to process hazard analysis (PHA) for fault tree analysis.

Fault tree analysis is widely used in system safety and reliability analysis, and fault tree analysis is also used in all major engineering fields.

A New Fault Tree Analysis for the ATP system of the CBTC system.

On the 2020 IEEE 23rd International Conference on Intelligent Transportation Systems (ITSC), P. Gao et al

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published the research on the safety function of the ATP system (a control system of the communication-based train control system), they proposed a new analysis method for the ATP system, the Dynamic Fault Tree analysis method. The Dynamic Fault Tree is a system of methods for evaluating the reliability and safety of a complex system, it is also a kind of deductive method, which is based on the fault event and is analyzed step by step according to the top-down sequence through certain logical reasoning steps until the result is reached. The Dynamic Fault Tree analysis method is devoted to modeling the fault logic according to the dynamic fault behavior, and conforms to the functional design of signal system. It is worth mentioning that logical analysis based on the Dynamic Fault Tree analysis method method often analyzes the emergence of problems at the same time, instead of analyzing it layer by layer, it can greatly improve the efficiency of problem solving.

The order of problem solving based on the Dynamic Fault Tree analysis method is:

1.

Identify the possible fault events.

2.

According to the possible fault events, establish the analysis process of them. 3.

Through the control system(just like the ATP control system), analyze whether the fault events occur. 4. If the fault events occur, solve them through the control system(just like the ATP control system).