An Integrated Process for System Maintenance, Fault Diagnosis and Support

So, the root cause problem elimination. It's really just a structured approach to eliminate problems...that's all it is. It's what usually happens when people say they do root cause, in my experience, this is the morning meeting and someone says motor tripped-out costing production loss. So, what happens in the morning meeting, now I haven't been to yours, but somewhere, the first thing people say is this a maintenance problem or is this an operations problem.

I was asked recently to give a second opinion on the cause of failure of an axial piston pump. The hydraulic pump had failed after a short period in service and my client had pursued a warranty claim with the manufacturer. The manufacturer rejected the warranty claim on the basis that the failure had been caused by contamination of the hydraulic fluid. The foundation for this assessment was scoring damage to the valve plate.

As a teacher and a practitioner of root cause analysis, I see not only the physical motions of going through such an effort, but also the psychology behind what makes or breaks it. When you consider the effort that goes into determining root causes and developing recommendations, why should it be such a hard sell to get something done?

If I have an unwanted situation which consumes resources and tends to happen in a repeated fashion then there is a possibility that it might be beneficial to figure out what is really causing this situation to occur and remove it so the situation does not occur again. This is generally referred to as Root Cause Analysis, finding the real cause of the problem and dealing with it rather than simply continuing to deal with the symptoms.

Semiconductor devices are almost always part of a larger, more complex piece of electronic equipment. These devices operate in concert with other circuit elements and are subject to system, subsystem and environmental influences. When equipment fails in the field or on the shop floor, technicians usually begin their evaluations with the unit's smallest, most easily replaceable module or subsystem. The subsystem is then sent to a lab, where technicians troubleshoot the problem to an individual component, which is then removed--often with less-than-controlled thermal, mechanical and electrical stresses--and submitted to a laboratory for analysis. Although this isn't the optimal failure analysis path, it is generally what actually happens.

To successfully carry out this mission, a root-cause investigation needs to be evidence-driven in accordance with a rigorous application of the bedrock of all root-cause methodologies: the Scientific Method. Consistent with the Scientific Method, underlying assumptions have to be questioned and conclusions have to be consistent with the available evidence, as well as with proven scientific facts and principles. Sometimes root-cause investigations fail to fulfill their primary mission and the failure recurs. In that regard, diagnosing the root cause of root-cause investigation failures is, in itself, an interesting topic. Here are three common reasons why some root-cause investigations fail their mission.

To understand why a part or equipment failed, how it failed must be first diagnosed. Different failure modes such as fatigue, brittle, and corrosion all have very different causes and very different solutions. If an investigation were to guess at the failure mode and guess wrongly, the planned remediation may not address the true cause of failure and additional failures may occur. This article considers three failed chain links and demonstrates the importance of identifying how something failed.