MTBF & MTTR
Mean Time Between Failures (MTBF) and Mean Time To Repair (MTTR) - two most-cited reliability metrics.
MTBF
2,190.0h
MTTR
9.00h
Formula, assumptions, and limits
MTBF applies to repairable items; MTTF to single-use. Shipboard critical equipment (main-engine bearings, steering gear) aims for MTBF of 20,000–50,000 h between overhauls.
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| Total operating hours | h | running-hours meter | |
| Total repair time | h | maintenance log | |
| Number of failures | - | failure report |