Root cause analysis that actually stops repeat failures

If the same failure keeps coming back, you are fixing a symptom. Root cause analysis (RCA) is the habit of asking why until you reach something you can change so it does not happen again.

Tool 1: the 5 Whys

Start with the problem and ask why it happened. Then ask why that happened. Keep going — usually around five times — until you reach a cause you can act on. A belt snapped. Why? It was worn. Why? It was not replaced on time. Why? There was no PM task for it. The fix is a PM task, not just a new belt.

Tool 2: the fishbone diagram

When there may be several causes, draw a fishbone. Put the problem at the head and draw branches for categories like people, methods, machines, materials, measurement and environment. Brainstorm possible causes on each branch, then test the likely ones.

Do it with the people who know

Run RCA with the technician who did the repair, the operator who saw it happen and someone who can approve the fix. Keep it short and focused on facts, not blame. People share more when they are not worried about being punished.

Close the loop

RCA only counts when it changes something: a new PM task, a design change, training, a better part. Create the follow-up work orders and check later that the failure did not return.