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Component reliability (MTBUR and MTBF)
Track how often a component is removed, and how many removals were real failures.
Reliability & managed IT servicesAerospace & aviationDefence
How it's worked out
- MTBUR = unit hours ÷ unscheduled removals. MTBF = unit hours ÷ confirmed failures. Unit hours = fleet hours × quantity per aircraft
- One reporting period
NoteA high no-fault-found rate wastes spares and shop time; it usually points to troubleshooting, not the part.
Source: ATA Spec 2000 reliability data; MRO practice
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