RCFA – Root Cause Failure Analysis
Failure is inevitable, and when failure does occur, RCFA is the process for discovering the root cause(s) for said failure and using that information to create a corrective action plan. While there are many methods to assist with RCFA – Fishbone Diagram (Ishikawa Diagram), 5 Whys, Cause Map – the process is generally the same.
The RCFA Process
Typically, RCFA is divided into three distinct phases: collection, analysis, and solution.
The purpose of the collection phase is to form a team to investigate the failure, define the problem, and finally collect data from the incident. When defining the problem, it is important to keep it short and simple to understand. Overly complex or problem statements biased towards particular solutions can lead to insufficient resolutions. Finally, it is time for the actual data collection. Normally, data can come in the form of failed components, pictures and reports, or staff testimony.
The analysis phase is focused exclusively on uncovering the failure cause and effect chain that ultimately leads to the root cause of failure. For more complex systems, use of the cause and effect methodology and a “fishbone” diagram are useful structures to integrate cross-functional impacts and see the overall picture of the failure. To avoid bias assumptions, an important guideline is to always follow the data.
You can download a fishbone diagram excel template here.
Finally, it is time to formulate a solution. The solution phase attempts to break the cause and effect chain as determined in the analysis phase. Subsequently, the more developed the cause chain, the greater the capability to break the chain. Generally, solutions are corrective and/or preventive actions and are associated with the identified failure action and/or condition causes with corresponding effectiveness evaluations.
When to Utilize RCFA
The most common time a failure analysis is employed is following a critical failure, which is why RCFA is often described as reactive. However, when used effectively, RCFA can be a proactive methodology to prevent future failures.
During equipment rebuild or disassembly following a malfunction, an initial RCFA cause map can provide useful data that would otherwise be missed. This data can be critical during the collection phase of a full RCFA. Additionally, it leads to insight on what caused the initial failure, possibly leading to corrective action before rebuild that will avoid future unplanned failures.
FMEA and RCFA on RCM
FMEA is an integral part of the Reliability Centered Maintenance (RCM) process because it helps classify failure modes and their effects, as described in SAE JA1011. After establishing failure modes, FMEA helps determine what maintenance strategies should be developed for its corresponding assets. Conversely, the RCFA process provides the opportunity to eliminate recurrent asset failures based on actual asset history analysis.
FMEA and RCFA assist a RCM methodology with both a proactive and reactive approach. While FMEA offers the benefit of reducing costs by discovering potential failure modes earlier in the process, RCFA provides increasingly accurate solutions with the use of historical failure data.