Root Cause Analysis
Why, why, why. . .
Comprehensive Failure Investigation
Looking for a basic, step-by-step approach to improved problem solving around your plant? Start here.Failure analysis, incident investigation, root cause analysis are among the terms used by organizations to refer to their various problem-solving approaches. Regardless of the name, these types of investigations typically boil down to three basic questions:
- What's the problem?
- Why did it happen?
- What should be done to prevent it from recurring?
These questions, or steps, are the framework for information collection that is then organized with the help of tools such as timelines, diagrams/photos and process maps. Together, these steps and tools lead to comprehensive failure investigation, which can be defined as the collection and organization of all necessary information to answer the three questions thoroughly and completely, supported by clear, concise documentation of the incident.
Two important points apply to every aspect of an investigation: focusing on principles and being specific.
Principles. . .
Principles are constants. They do not change from problem to problem. The cause-and-effect principle is fundamental to all investigations. This principle applies to equipment failures, supply chain problems, production outages, customer service issues and people problems the same way. By focusing on the principle of cause-and-effect, an organization can develop a consistent approach to investigating and solving all problems. If you confront a problem that appears to contradict basic physics, check your assumptions, because some are not accurate.
Remember: There are no equipment failures or problems in a facility that defy the laws of physics and chemistry.
There always will be an explanation or truth to what has already happened. Think of this in terms of the terrain in your hometown. The map of the town represents the terrain. The creation of the town map should be an objective exercise because the roads already fit together in a particular way. The map should match the actual terrain, just as the investigation should match the incident that occurred.
Many people think of cause and effect as a linear relationship, where an effect has a cause. In fact, cause-and-effect is an example of a system. A system has parts just like an effect has causes. The equipment downtime came about because a part failed. We find that the part failed because of fatigue. The next question is: "Why did it fatigue?". . . and the why questions just keep coming. Most organizations mistakenly believe that an investigation is about finding the one cause, or "root cause."
Remember: An effect doesn't have a single cause--it has "causes," which reveal different ways to solve the problem.
Be specific. . .
The word "analysis" means to "break down into parts." Failure analysis, problem analysis and root cause analysis all start with a problem, then break it down into parts-- which are the causes. Identifying the causes reveals additional ways that the problem may be solved. As the causes become more specific (detailed), the solutions also become more specific.
Remember: Problems are solved when specific action is taken. Problems are not solved in general--the devil is in the details.
One common mistake that many organizations make is trying to group an entire investigation into one category. This makes the incident more general, not more specific. The five most common generalizations are: human error, procedure not followed, equipment failure, training inadequate and design. Many groups believe that the end of an investigation has been reached if they can get to one of these five categories.
Remember: Don't generalize an investigation--ask more "why" questions and be specific.