Latent Root Cause

A good root cause analysis (RCA) should produce more than just the physical root cause.  It is important to discover the physical root cause to fix the immediate problem.  But delving deeper into the systemic, then all the way to the latent cause helps transform your business for the better.

The latent root cause involves practices and cultural norms that allow failures to happen.  I’ll say that again, the latent root cause is the practice that allowed the failure to happen.  Solving the latent root cause, means solving a management problem.

It’s easy to know when you have reached the latent cause, because the terminology has changed from ‘they’ to ‘we’.  It is no longer someone else who has to act, but we, as management, that have to act.

Let me take you through an RCA that I was involved in as a plant manager.  Note: after they are solved, RCA’s can be explained simply.  But the process is grueling, takes many iterations and can be extremely frustrating.  It is easy to get distracted and end an RCA after the physical root cause.  But if the problem was important enough to warrant an RCA (not just troubleshooting), then it is worth it to the organization to finish the RCA and find the systemic and latent causes.

Problem Statement:  Food Product did not meet consistency expectations, but did not present a food safety hazard.

Occurrence:  Product left plant at expectation, and arrived at most sites as expected, however product shipped over the Rocky Mountains lost consistency.

After much research into what made the product the right consistency, and a thorough inspection of the production equipment, it was found that the colloid mill was not shearing the product finely enough to produce the sustained viscosity needed.  When the product was shipped over high altitude it became runny.  Other product became runny before code date, but the high altitude shipment actually helped by alerting us to the problem within days of the production run.

Production Process :  The colloid mill blade spacing was set by adjusting the dial on the outside.  There was an SOP that indicated where to set the dial.

Physical Root Cause:  The mill was dismantled and the thickness of the blade was measured.  It was still a useable blade, but the dial setting should have been adjusted for blade wear.

Systemic Root Cause:  SOPs were created and did not take into account equipment wear.

Latent Root Cause:  No one thought about how equipment wear would effect product quality.  There was no program to adjust SOPs over time to account for blade wear.  But requiring production to follow the SOP, management did not have a provision to adjust requirements as needed over time.  The blade was known to wear, but the spacing adjustment did not account for that wear in the SOP.  Management allowed for using a worn (but still within spec) blade, but did not provide instructions on how to use that thinner blade.

The result of determining the latent root cause was a plant wide review of all equipment that could wear.  There was already a program to periodically measure the mill blades to ensure they maintained safe thickness.  So, a process was added to the inspection to record the blade thickness and adjust SOPs accordingly.

Other equipment was reviewed, to determine if changes needed to be made.  Positive displacement lobe pumps are a common wear item in food plants.  Using pressure and flow settings compensate for lobe wear.  Agitators and mixers were also reviewed to set standards.  A clearance inspection program was set up for them.

By driving to the latent root, we were able to apply the physical root cause (wear) to equipment beyond the colloid mill.  This should prevent future quality issues and lead to better care and understanding of the equipment and its importance in the manufacturing process.

Finding the latent root cause prompts management to act and change the processes.  It can be more expensive and involve more areas of the business than this problem.  It is not uncommon to see capital expenditures or changes in operating philosophy.

The more RCAs that your organization drives to latent root cause, the less RCAs overall will be needed.  This is because solving these management issues, has a broader impact than solving only the physical issues.

You will be operating more proactively, and less reactively.  I encourage you to use an experienced coach to learn the process of driving to the multiple root causes.  But once you understand the process, you and your organization will continue to drive toward solving the latent issues.  You will not be satisfied to stop at the physical root cause.


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