Repeat failures are invitations to move from “what broke?” to “what condition keeps creating this failure?”
SURVIVAL RULE: A repeat part replacement is not automatically a root-cause fix.
Fixing the failed part is not always fixing the failure
A component replacement restores function, but repeat failures demand a second question: why did this part fail here? The answer may involve contamination, heat, vibration, overload, poor access, wrong specification, wiring strain, process abuse, or maintenance practice.
If the same proximity sensor breaks every month because product physically hits its bracket, keeping more spare sensors is not root-cause control. Protecting or relocating the sensor may be.
Field habit: Flag repeat failures and compare physical location, operating conditions, and history.
Common trap: Do not run a full formal root-cause process for every minor failure; use depth proportional to consequence and repetition.
Use ‘why’ to move from event to system
Repeatedly asking why can help move from the visible failure to the condition that allowed it. The method is not about forcing exactly five answers. Stop when you reach a cause that is supported by evidence and can be controlled.
Conveyor stopped → overload tripped → bearing seized → bearing ran dry → lubrication point was missed → PM route did not include it. The corrective action is not merely ‘replace bearing.’
Field habit: At each step, ask what evidence supports the link and what alternative explanation exists.
Common trap: Do not use ‘operator error’ as the final answer without asking why the system allowed or encouraged that error.
Quick check
What should be true at this point in the sequence?
What evidence can prove or eliminate this section of the system?
What changed recently or only under the failing condition?
Separate corrective action from preventive action
Corrective action restores the failed asset. Preventive action changes the conditions that produced the failure or improves detection. These may be different tasks owned by different people.
Replacing a cracked cable is corrective. Adding strain relief, rerouting the cable, and inspecting similar axes are preventive actions.
Field habit: Write both actions when the failure is significant or repetitive.
Common trap: Do not claim prevention when the action is only another replacement of the same part.
Verify that the cause stayed gone
A root-cause action is a hypothesis until results support it. Decide what outcome should change: failure rate, temperature, current, leak rate, sensor damage, alarm frequency, or inspection finding. Then check after an appropriate period.
If a cable route is modified to eliminate flex damage, inspect it after several weeks and compare communication faults with the previous period.
Field habit: Close root-cause actions with evidence of effectiveness, not only completion.
Common trap: Do not let improvement work disappear once the machine is running again.
Quick check
What should be true at this point in the sequence?
What evidence can prove or eliminate this section of the system?
What changed recently or only under the failing condition?
Field Exercise
Choose one repeat failure and draw a cause chain that goes one level deeper than the replaced part.