Root Cause Analysis (Engineering)

A structured engineering investigation methodology that goes beyond identifying what failed and how it failed to determine why it failed — the fundamental root cause that, if eliminated, would prevent recurrence. Engineering RCA is applied to component failures, system failures, and process upsets. Methodology: (1) Preserve evidence — collect failed parts, photographs, operating data, maintenance records before clean-up. (2) Define the problem — specific, measurable description of the failure event, timeline, and impact. (3) Determine physical cause — metallurgical analysis (fractography, microstructure, hardness), chemical analysis, dimensional verification, and operating condition reconstruction. (4) Determine human and systemic causes — what actions/inactions contributed, what organizational factors enabled the failure. (5) Corrective actions — specific, actionable recommendations with owners and deadlines. Tools: 5 Whys (iterative questioning), Ishikawa/fishbone (categorized brainstorming), fault tree analysis (Boolean logic), and timeline analysis. Per ANSI/API 689, DOE-NE-STD-1004-92, and ASTM E2332 (investigation methodology). Example: a V-belt failure RCA might trace from "belt broke" to "sidewall glazing" to "under-tensioning" to "no tension gauge available" to "maintenance tool budget eliminated" — the root cause is organizational, not mechanical.