Use proportional analysis: enough to prevent recurrence, not enough to paralyze routine maintenance.
What to understand
Not every broken switch needs a formal root cause meeting. Match the depth of analysis to safety, cost, recurrence, production impact, and uncertainty.
Start by turning the idea into an observable question. What should the machine, component, person, or process be doing at this moment, and what evidence would prove that it is doing it? Defining normal first gives your troubleshooting a reference point and prevents you from reacting to the first unusual thing you notice.
How to apply it
A useful root cause statement describes a controllable mechanism. “Operator error” is usually too shallow; ask what system allowed the error and how the process can become more robust.
Apply the idea one boundary at a time. Confirm one condition, record what you learned, and only then move to the next point in the chain. This makes your work easier to explain and greatly reduces the temptation to swap parts or change several variables at once.
What good work looks like
Corrective actions should change a condition: design, standard, PM, training, spare strategy, environment, or operating method.
Good maintenance work leaves a trail of evidence. Measurements, alarm times, verified states, photos where permitted, and clear work-order notes let another technician understand why you made the repair and whether the same failure mechanism returns later.
Field scenario
A coupling fails twice in three months. Investigation shows the motor base is soft-footed, causing misalignment after tightening. The corrective action is not “use a stronger coupling.” It is to correct the base condition, align the shafts, and add alignment verification to the replacement standard.
After the immediate repair, capture the point in the sequence where the expected condition was lost and what evidence proved the cause. That small discipline turns a one-time fix into knowledge the whole maintenance team can reuse.
Field checklist
Common mistakes to avoid
Using “5 Whys” mechanically with no evidence
Stopping at human error
Choosing actions that cannot be verified
Closing root-cause actions when paperwork is complete rather than > when risk is reduced
Ask yourself: If this machine failed again on the next shift, what information could I leave behind that would make the next diagnosis faster and safer?
90-day action
Before moving on, choose one task from this chapter and perform it during normal work. Record what you learned in your plant notebook. The value of the first 90 days comes from turning concepts into repeatable behavior, not from reading alone.
CHAPTER 19