Root Cause Analysis: The 5 Whys and Fishbone Diagrams

Finding the Real Cause of Problems

Treating symptoms rather than root causes guarantees that problems will recur. Two classic tools help teams identify why issues arise.

The 5 Whys By repeatedly asking "Why?" (typically five times), you peel away superficial layers to reach root causes. - *Example*: The machine stopped. Why? The fuse blew. Why? The pump was overloaded. Why? The bearing was dry. Why? The lubrication schedule was missed. Why? Maintenance instructions were not documented. - The root cause is not the blown fuse—it is the absence of documented maintenance procedures.

Cause-and-Effect (Ishikawa / Fishbone) Diagram For complex problems with multiple contributing factors, the Fishbone diagram organizes potential causes into standard categories: - **People**: Training, skill gaps, fatigue - **Methods**: Procedures, instructions, handoffs - **Machines**: Tools, maintenance, hardware - **Materials**: Supplier inputs, specifications - **Measurement**: Data accuracy, calibration - **Environment**: Temperature, lighting, organizational culture