How Root Cause Analysis Benefits Maintenance

Root cause analysis (RCA) helps manufacturers understand why a piece of machinery has failed using a variety of tools and techniques. The aim is to prevent the problem occurring again. Let’s take a closer look at what the root cause analysis steps are and how they work.

A root cause definition is that it is the underlying problem that leads to failure. Root cause analysis uncovers the cause of machinery failure, using methods such as the fishbone diagram, 5 whys and Pareto chart. According to the American Society for Quality, a root cause is ‘a factor that caused a nonconformance and should be permanently eliminated through process improvement. The root cause is the core issue — the highest-level cause — that sets in motion the entire cause-and-effect reaction that ultimately leads to the problem(s)’.

In engineering analytics, a root cause analysis report is a form of systems failure analysis. In maintenance, this means resolving the true cause of mechanical problems, whether they be technical, related to human factors, or the result of systems and processes.

The fishbone diagram and the 5 whys are just two of the tools available for failure analysis engineering. Failure modes and effects analysis helps engineers to prioritise maintenance actions by giving them risk priority numbers. It aims to anticipate and mitigate the impact of failure proactively and is widely used in aerospace and manufacturing. 

Advantages include optimised production costs and a structured framework for prioritising corrective actions. As well as maintenance, the system can be used to improve business processes and product design and development. 

Like the fishbone diagram, fault tree analysis is a graphical technique that uses Boolean logic to map out human and system failures. Fault tree analysis describes the relationships between asset failures and subsystems and uses logic to identify causes and effects. 

Pareto analysis and Pareto charts are based on the work of an Italian economist, Vilfredo Pareto. He stated that 80 percent of consequences stem from 20 percent of causes (known as Pareto’s Principle, or the ‘80/20 Rule’). Engineers use Pareto charts to show how most failures are caused by a small number of factors. It’s then possible to prioritise correcting the causes that result in the majority of undesirable effects.

Six Sigma methodology can also be used in engineering analytics to improve a maintenance regime and carry out root cause analysis. Six Sigma uses the DMAIC process – define, measure, analyse, improve, control – to minimise errors in a production environment. 

All the above techniques are used by engineers when identifying the causes of machinery failure. Failure modes and effects analysis (FMEA) is also widely used by maintenance managers. It looks for all the errors in a machine, product or process. 

Finally, don’t forget that a computerised maintenance management system (CMMS) can also perform root cause analysis by allowing engineers to analyse asset maintenance data when failure occurs. For example, the work orders issued to technicians by a CMMS provide information on problems and how they were resolved.