Root Cause Analysis

A repair that addresses the symptom without finding the root cause reliably comes back - often worse, since the underlying cause kept operating unaddressed the whole time. Two lightweight methods cover most bench-level investigations without requiring a full formal quality-engineering process.

5 Whys

Ask "why" repeatedly against the failure until you reach a cause you can actually act on - a part, a procedure, a training gap - not just a restated symptom. A worked example: the infusion pump alarmed occlusion → why? the line was kinked → why? the tubing was routed under the bed rail → why? there was no strain-relief clip provided at bedside → why? the unit's accessory kit was missing a component at incoming inspection. The real fix here isn't "untangle tubing" - it's verifying accessory kits more carefully at incoming inspection, which prevents the whole chain from recurring on other units too.

Fishbone (Ishikawa) diagram

Sorts candidate causes into categories - equipment, process, people, materials, environment - when a fault has multiple plausible contributors and you need to rule them out systematically rather than guess. This is the better tool when a single "why" chain doesn't capture the real picture - for instance, a recurring monitor cable failure might have contributing factors from more than one category at once (a lower-durability replacement cable purchased on cost, combined with a floor layout that forces awkward cable routing, combined with staff not being trained on gentle disconnection technique).

When to escalate beyond the repair ticket

For a repeat failure on the same device, or the same failure across multiple units of the same model, escalate beyond the individual repair ticket - check whether it meets your facility's threshold for a hazard/adverse-event report (Chapter 16) rather than treating each occurrence as an isolated repair. A pattern across multiple units is exactly the signal that distinguishes a design or batch issue from an individual unit's bad luck, and it's the kind of finding that, reported upward, can prevent the same failure at other facilities too.