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A fault tree is an investigation tool that can identify and resolve system or process faults. It is also helpful in finding the root cause of any incident. An organization or company may have multiple fault trees based on defects, errors or problems.
Just as a fishbone tool has a fishbone structure, a fault tree has a tree root structure. Root branches represent potential causes of errors or problems.
In some errors or problems the “5 Whys” tool doesn’t work and you can’t find the root cause of the problem. This tool works with the “5 Whys” tool, which requires you to ask a “why” every time you create a fault tree when you want to find the cause behind a problem. In fact, the “5 Whys” tool alone won’t work when there are multiple possible causes of a complex phenomenon, and it will confuse you to find the root cause of the problem. You can more efficiently map the root cause of this problem using a fault tree diagram.
In such cases, all possible causes are written step by step in a systematic manner by asking “how” or “why” as questions. It forms a structure like the root of a tree. A fault tree for cross-contamination between two products is created here to better understand it.
Write the event or problem at the top of the diagram, and then the second row contains elements directly related to the problem. Then do the same for these elements and write the possible reasons related to these elements in the next row. You need to follow this process until you find the reasons shown in the above diagram.
In the figure given above, we are trying to find the root cause of cross-contamination of two products, where during quality control analysis of one product B some traces of other product A are found. There are three possible reasons for this. Cross-contamination such as equipment, area and AHU.
Each of these three possible causes is further questioned to find out the probable cause. If the equipment is not cleaned properly, it can have two reasons, first, if the production equipment is not cleaned and the other if the cleaning method is not adequate.
Now in the next step, we try to find the cause of these factors. For example, if the equipment is not cleaned, it may happen because the cleaning person followed an incorrect cleaning procedure or the cleaning person was untrained.
The other two primary factors are similarly analyzed to find out their possible causes. You can check them in the diagram. This way, you can find the root cause of the problem easily and efficiently.
Usually “5 Whys” tool is considered to find the root cause of any problem or incident in pharmaceuticals but now you can make it more effective and accurate by using it with fault tree diagram according to the complexity of the problem.
