One of the most common inventory questions is also one of the most misunderstood: what makes a spare part critical?
Criticality is about consequence
A part becomes critical when its absence can create an unacceptable operational consequence and the organization cannot recover quickly enough through normal supply channels.
That consequence may involve safety, environmental exposure, production loss, mission interruption, equipment damage, regulatory impact, or extended downtime.
Consider more than usage
Low usage does not mean low importance. Some of the most important spares may never be consumed during normal operations. Evaluate failure consequence, equipment criticality, lead time, supplier availability, repair options, interchangeability, probability of failure, and the cost of downtime.
Critical-spares decisions should be documented
A repeatable criticality method helps explain why an item is stocked, how much should be held, and when the decision should be revisited. It also makes it easier to challenge inventory that is being retained only because “we have always kept one.”