How do you prepare to conduct an FTA analysis?

• Schedule time to perform the Fault Tree Analysis,
• Form a team, consisting of Experts from different fields related to the problem,
• Present the objectives and principles of the FTA analysis to the team.

How to perform FTA analysis?

1. Define the purpose of the analysis

First, it is necessary to consider the purpose of the analysis itself. What problem do we want to analyze? What influenced the occurrence of the problem? What events do we want to verify? Properly defining the purpose of the analysis helps focus on the right aspects of the problem.

2. Divide potential causes into categories

The next step is to divide the potential causes affecting the problem we are studying into 4 main categories. Here we use the 4M principle, which is:

• Man – factors related to human influence on the occurrence of the problem.
• Machine – a category of factors related to the technical part of the process – machines, equipment, tools and their impact on the occurrence of this problem.
• Method – a group of factors related to the way in which the process is implemented, instructions, technological flow and parameters.
• Material – factors related to the physical and chemical properties of the raw materials used to make the product and their quality compatibility.

Each factor affecting the problem forms a node (cause), and we represent the relationships between these factors as branches (effects).

3. Fault Tree Analysis

We move on to analysis. Fault Tree Analysis involves identifying different combinations of causes that could lead to the problem under study. We assign each cause a probability level for its occurrence and its impact on the problem. You can use statistical data, expert opinion, or historical data to determine the level of probability and impact on the problem.

Typically, a numerical scale of 1 to 10 is used to determine the impact size on the problem and the level of probability.

For example, a cause for which we rated the probability of occurrence at 10 is the cause most likely to have had a direct impact on the occurrence of the problem. The same cause could at the same time be rated at 1 in terms of the impact of the occurrence of this cause on the identified problem. In such a situation, we should not worry too much about this cause, because its impact on the analyzed problem is very small.

By analyzing the previously identified causes in this way, we are able to determine which causes had the greatest impact on the problem.

For more practical FTA examples, see our “Basic Problem Solving Tools” course.

4. Evaluate results, draw conclusions, plan actions

The next step is to evaluate the results of the analysis and draw conclusions that will translate into appropriate corrective or risk minimization actions.

We do not focus on all potential causes of the problem. It is useful to focus on the causes that had the highest probability scale and high impact on the problem. For these most likely and significant causes, we plan corrective actions and activities that will minimize the risk of their occurrence.

5. Be careful

You need to know that FTA analysis is not a one-time activity. The analysis should be updated as the environment of the problem under study changes. Recall the 4M principle and ask yourself if any of the categories of factors have changed recently?

The FTA method should be used regularly. By systematically responding to changes and new risks, as well as measures to minimize risks, we increase the reliability of processes and systems.

Benefits of using the FTA method

• Understanding the causes of the error,
• Identifying areas that need improvement,
• Defining new standards, minimizing the creation of the problem,
• Improving safety and reducing the risk of unwanted events,
• Increasing the reliability of processes and systems,
• Enabling informed decisions on defining corrective actions.