RCFA: root cause failure analysis for equipment, step by step

What is RCFA (root cause failure analysis)

Root cause failure analysis (RCFA) is a structured investigation of an equipment failure to find the cause that, once removed, stops the event from happening again. It starts from the physical evidence of the failed component, moves through hypotheses and ends in corrective actions with an owner and a due date.

The goal differs from a normal repair: a repair gets the machine back into production, while RCFA makes sure the same failure does not return. In maintenance, that replaces the "break, fix, break again" loop with a record of what happened, why, and what changed in the process.

RCFA visual map

The map summarizes the flow from event to action, with the worked example from this article.

The 6 steps of RCFA

1. Preserve the evidence. Before cleaning and repairing, photograph, tag and keep the failed parts, oil samples, the location and the equipment records. Without evidence, the analysis becomes opinion.
2. Describe the event. What failed, when, under which operating condition, who was operating, and what changed in the last few weeks.
3. List hypotheses. Use a fishbone diagram or a fault tree to list every possible cause, discarding none before it is tested.
4. Test each hypothesis against evidence. Each one is confirmed or rejected by data: measurement, part inspection, history, lab analysis.
5. Reach the root cause. Follow the chain of physical causes down to the latent cause (process, method, design, training). The 5 Whys helps organize the reasoning.
6. Define and follow up actions. Corrective (remove the cause) and containment (protect until then), each with an owner, a due date and an effectiveness check.

The three levels of cause

Stopping at the physical cause leads to swapping parts. Stopping at the human cause leads to blaming people. The root sits in the system: procedure, plan, design or training.

Evidence: the 5 Ps

A simple way to organize data collection is to split evidence into five groups, known as the 5 Ps in the root cause analysis literature:

• Parts: failed components, fractures, wear, contamination.
• Position: where they were, alignment, clearances, surroundings.
• People: interviews with the operator and mechanic, without hunting for blame.
• Paper: work orders, maintenance plan, procedures, process records.
• Paradigms: beliefs such as "this pump always fails" that block the investigation.

Worked example: mechanical seal on pump P-204

Fictional example to illustrate the method. A centrifugal process pump had its mechanical seal replaced 4 times in 12 months. Each stoppage cost:

Analysis steps:

• Evidence: the carbon seal face was cracked with thermal-shock marks; the suction strainer was clogged; pump vibration measured during the analysis was high.
• Hypotheses tested: misalignment (rejected: alignment within tolerance), wrong seal (rejected: specification checked), dry running/cavitation (confirmed: a clogged strainer lowers suction pressure).
• Cause chain: the seal cracked because the pump cavitated; it cavitated because the strainer clogged; it clogged because nobody cleaned it; nobody cleaned it because the maintenance plan had no such task.
• Root cause: a maintenance plan built without analyzing the asset's failures.
• Actions: weekly strainer cleaning in the plan; a differential pressure gauge on the strainer with an alarm limit; a plan review based on history. Estimated investment in the example: R$ 6,500.

If the 4 failures stop, the potential gain is R$ 82,080 per year against R$ 6,500 invested, that is, 82,080 ÷ 6,500 ≈ 12.6 times. The result only counts after you confirm, over the following months, that the failure has not come back.

When to open an RCFA

You cannot analyze every failure. Define trigger criteria and write them into the procedure. Examples used in practice:

To choose where to look first, build a Pareto chart of downtime hours per asset from your CMMS. The MTBF and MTTR indicators show whether the RCFA reduced failure frequency.

RCFA, 5 Whys, FTA and 8D: when to use each

In practice, RCFA uses the others as tools. For failures that repeat because a failure mode was poorly anticipated, FMEA and RCM are the next step to adjust the maintenance strategy.

Common mistakes

• Cleaning up before collecting evidence. The failed part is the main proof.
• Stopping at the human cause. "Operator error" is not a root cause: ask why the system allowed the error.
• Picking the easiest cause. The root cause must be confirmed by data, not by consensus.
• Generic actions such as "train the team" or "pay more attention", with no effectiveness check.
• Not closing the loop. Without tracking recurrence through MTBF, you do not know whether the action worked.
• Analyzing everything. Without trigger criteria, the team burns out and analyses get shallow.

Frequently asked questions

What does RCFA stand for?

Root Cause Failure Analysis: a method to find out why equipment failed and how to prevent a repeat.

What is the difference between RCFA and 5 Whys?

5 Whys is a reasoning technique; RCFA is the full process, with evidence collection, hypothesis testing and an action plan. 5 Whys can be used inside it.

How long does an RCFA take?

It depends on complexity. A simple failure can be closed in a few hours; serious events need days of data collection and group analysis.

Who should take part?

Maintenance, operations and, when needed, engineering, quality and the component supplier. A facilitator runs the process.

How do you measure whether RCFA worked?

By the drop in failure frequency: higher MTBF, fewer corrective work orders for the same failure mode and lower downtime cost in the following period.

Do I need software to run an RCFA?

No. A spreadsheet and a form are enough. A CMMS helps pull history and track actions.

About the author

Vagner Soares

Lean Manufacturing & Behavioral Management Specialist

Over 20 years in the automotive and metalworking industries (GM and Dana), Lean Manufacturing practitioner since 2006. SENAI instructor and mentor in Brazil’s Brasil Mais Produtivo program, delivering consulting, training and audits for 50+ companies, combining quality, productivity and people development.

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