The Five Whys Approach
Most failure investigations stop at the first plausible cause — pushing to the underlying root cause actually prevents recurrence.
The 'five whys' technique asks 'why' repeatedly until the root cause emerges — typically within 4-6 layers. 'The bearing failed because of lack of lubrication' isn't the root cause until you also ask why the lubrication was missed.
Document the analysis even for minor failures — patterns across small failures reveal common root causes that wouldn't be visible looking at one event in isolation.
Root cause is typically a process or system issue, not an individual fault — 'the operator forgot' is not a root cause; it's the symptom that reveals 'our PM checklist didn't include that step.'
Avoid blame in the RCA process — operators participate fully only when the process is about preventing the next failure, not assigning responsibility for the last one.
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