I recently worked on an involved failure analysis. The investigation was far reaching – it covered design specifications, quality specifications, material manufacturing, and the differences between US and international standards.
From a design standpoint – the material could not withstand the anticipated design loads and resulted in a shorter life expectancy than desired. One could have stopped after the metallurgical failure analysis and never looked at the deeper issues. Stopping here would have left the problem unsolved.
The next question that had to be asked was … “Why was the material defective?” Was it just one bad batch? Did the wrong type of material get used? Was the proper heat treatment specified for the part? Without knowing the answers to these types of questions, a true solution to the problem could not be implemented.
As the analysis continued, the true solution to the problem involved
- clarification of design specifications,
- the application of international standards,
- the interpretation and understanding of US standards, and
- the metallurgical analysis of numerous steel samples.
Finding the true root cause must be coupled with a plan for corrective action in order to prevent failures from continuing. No matter what process you use for root cause determination – the process must continue until the true failure mode is determined and a corrective action plan has been developed.