Like many have said I have also been involved in root cause analysis to examine the reasoning behind something failing. In many cases, most of the root cause analysis I have done involves a lot for a product failing. From my experience, the investigation usually involves QC rejecting the lot after in process manufacturing inspection. Many times QC either does a 100% inspection or an AQL and during that inspection something fails. Most of the lot failures that I have encountered have occurred due to foreign matter being on the product. At the end of the day, if the lot can’t be reworked it ends up being completely scrapped and I consider that a failure.

In another situation, we had a cranial stabilization device that was used to hold patients heads during neurosurgery. We were getting complaints in the field that the product was breaking due to stress on the screws holding the knob handles in place and as a result the product would break or collapse. We had to do an investigation and open a huge initiative to essentially change the material of the screws.