Change analysis, root cause determination

The guidance for tliis element covers responsibilities and authorities, determination of the significance of a quality (ESH/PSM) related problem, root cause investigation, cause-and-effect analysis, preventive actions and additional controls, and change documentation. For ESH/PSM, this element might be interpreted as covering both potential hazards as well as actual problems. 

Once the causal factors have been identified, the factors are analyzed using a root cause analysis tool, such as 5-AVhys or predefined trees. See Chapter 9 for a more detailed discussion of Barrier Analysis (sometimes called hazard-barrier-target analysis or HBTA) and Change Analysis (also referred to as Change Evaluation/Analysis or CE/A). In essence, these tools act as a filter to limit the number of factors, which are subjected to further analysis to determine root causes. 

The first consideration in defect analysis is whether the part has been handled after removal from service. Handling can alter the appearance or contaminate it to the point that either failure analysis could not be conducted or the root cause could not be determined. Surface analysis techniques are sensitive to handling and cannot distinguish between the changes caused by the failure and contamination. The best practice is to minimize handling the part and keep track of the history of the part. There are certain steps that frequently have to be taken such as decontamination of parts that have been in contact with corrosive, toxic, or flammable chemicals. A log should be considered to keep track of what has been done to the part, which may help explain any unforeseen consequences of part handling. 

Once the core management team has signed off on the proposed change, the MOC flows to a project team whose task is to decide on what actual change is most appropriate. The project team can use a root cause analysis to help them determine the best solution to the problem that has been identified. 

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