Once we designed and implanted our Reliability-Centered Maintenance program we can see that failures still remain in our equipment, some failures are unplanned and other are planned but our RCM plan is not able to avoid. What can we do?
We can repair the failure as soon as possible, but probably the failure ocurrs often, so we don't solve anything.
The solution is to perform a Root Cause Analysis - RCA that allows us to know the root cause of failures, so we can avoid the cause and prevent the failure occurs again. Exactly RCA is a process to isolate factors to produce a failure and determine optimal actions to ensure the failure is not being repeated over again.
Several techniques can be used to perform Root Cause Analysis, from the easiest 5 Whys, of Lean Manufacturing methodology, that can be applied by the machine operators, to much complex techniques such as Events and Causal Charting, Change Analysis, Fishbone (Ishikawa) Diagrams, Fault Tree Analysis (FTA) or Failure Modes and Effects Analysis (FMEA) completed with interviews and tests.
Whatever the methodology, an effective process must meet the following criteria: define the problem, establish relationships between cause and problem, present evidences, explain how to prevent recurrence of the problem, assess measures and facilitate the writing of result reports. Methodologies listed before not always provide an acceptable response to these criteria, so the results are unsatisfactory.
Dean L. Gano, inventor of Apollo RCA, proposes an evolution of this methodology in his last book RealityCharting – Seven Steps to Effective Problem-Solving and Strategies for Personal Success, it is based in seven steps:
1. Define the problem. It must include answers related with What is the problem, When did it happen, Where did it happen and what is the significance of the problem, best in Dollars/Pounds/Euros.
2. Determine the causal relationships. When we have identified the problem, we must identify a minimum of two causes, one of which should be an Action and other a Condition. In each cause we must identify new causes or a reason to conclude the analysis line.
3. Provide a graphical representation. To draw a graphic chart to show the logic succession of events and causes, it does easier to find relations among them.
4. Provide evidence, of each cause, best if we have photos, data and test results to confirm both events and causes.
5. Determine if causes are sufficient and necessary. It means to confirm the event should not ocur without the cause, and to confirm the event doesn't need more causes.
6. Identify effective solutions. When we have identified the sufficient and necessary causes we can propose solutions, they must meet the following criteria: Prevent recurrence, Be within your control, Meet your goals and objectives, and Not cause other problems that you are aware of. We assess solutions by costs-benefits analysis.
7. Implement and track solutions. Finally, solutions must be implanted and monitorized to check their effectiveness.