An Integrated Process for System Maintenance, Fault Diagnosis and Support

There are many types of RCA tools available to organizations, including 5 Why?, Fault Tree Analysis, Interrelation Diagrams, Ishikawa Diagrams (Fishbone, Cause and Effect) and many others. A great example is the 5 Why? method: starting with the incident itself, an RCA team would continue asking “Why did this happen?” until they arrive at the root cause. Refer to the following example:

How often is the phrase "The ROOT Cause of the problem" used at your plant/mill? This phrase is a bit symptomatic of how Root Cause Analysis is thought of. The phrase implies that there is only one "cause" to the problem. Rarely is there a single root cause to any given problem. Usually, there are several reasons; to be sure there are several "technical causes" that interact to create a breakdown/failure.

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.

A fault tree is constructed starting with the final failure and progressively tracing each cause that led to the previous cause. This continues till the trail can be traced back no further. Each result of a cause must clearly flow from its predecessor (the one before it). If it is clear that a step is missing between causes it is added in and evidence looked for to support its presence. Below is a sample fault tree for the moral story of the kingdom lost because of a missing horseshoe nail.

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.

Root Cause Analysis represents one of the greatest challenges in reliability program development, requiring a broad understanding of management processes, structured problem solving and behavior. Developing a Root Cause Analysis work process will require effort and persistence as well as new thinking about organizational structure and resource priorities. The potential improvements from developing an effective Root Cause Analysis work process are significant. Most manufacturing processes have opportunities for improvement and cost reduction that have not been obtainable with current efforts. In some cases, these opportunities could represent competitive advantages in manufacturing strategies and processes.

When a bearing in a critical piece of equipment fails prematurely, a maintenance specialist knows the failure usually indicates there is more here than meets the eye. What the untutored eye sees is a failed bearing and little more. However, a premature bearing failure is symptomatic of other problems that, if left untreated, will cause the same kind of failure to occur again.