Probability
Component Failure Probability Calculator
Measure component-period exposure, expected failures, zero- and any-failure probability, expected replacement expense, service-impact hours, downtime cost, and total failure consequence.
Total component-period exposures-
Expected component failures-
Probability of zero failures-
Probability of at least one failure-
Expected replacement cost-
Expected gross downtime hours-
Expected service-impact hours-
Expected service-impact cost-
Expected total failure cost-
Decision view
Fleet exposure, reliability curve, and cost consequence
Fleet exposure, reliability curve, and cost consequenceComponent-period exposure accumulates across missions; the zero-failure survival curve, any-failure threshold, detected share, replacement cost, and service-impact cost are shown separately.
Exact scenario comparisonFailure probability per component-period (%) changes while all other entered assumptions remain constant.
| Failure probability per component-period (%) | Total component-period exposures | Expected component failures | Probability of zero failures | Probability of at least one failure | Expected replacement cost | Expected gross downtime hours | Expected service-impact hours | Expected service-impact cost | Expected total failure cost |
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How to use Component Failure Probability Calculator
- Enter components, duty periods, and per-period failure probability.
- Enter direct replacement and downtime consequence.
- Apply pre-impact detection coverage and review both reliability and cost views.
Calculator guide
Understanding Component Failure Probability Calculator
A component fleet accumulates risk across both units and duty periods. This page distinguishes expected failure count from the chance of any failure, then separates replacement cost from detection-adjusted service disruption.
Detailed calculation process
Detailed component-fleet failure calculation
The default fleet contains 24 components observed over 12 comparable missions.
General formula: X=cmE=XpP_0=(1-p)^XP_any=1-P_0H=E*h(1-d)C=E*r+H*k Exposure drives both expected count and probability of at least one failure. Detection changes only service-impact downtime in this model.
What each symbol means
Worked substitution with the default inputs
Expected replacement and downtime costs add to the displayed total, while zero-failure and any-failure probabilities sum to 100%.
Worked situations
Practical examples
- Twenty-four components across twelve missions create 288 component-period exposures.
- At 0.35% per exposure, the expected count is 1.008 while the chance of at least one failure is about 63.5%.
Better inputs
Useful tips
- Estimate the probability from comparable components and duty severity.
- Keep mission-period definitions consistent.
- Use detection coverage only for failures genuinely intercepted before service impact.
Before relying on the result
Limitations and common mistakes
- The model assumes equal independent component-period risks.
- Wear-out, common-cause failure, repair queues, spare shortages, and cascading failures are excluded.
- Expected cost is not a worst-case loss estimate.
Reference
Key terms
- Component-period
- One component exposed for one mission or duty interval.
- Detection coverage
- Share of failures intercepted before they create entered service downtime.
- Expected failures
- Probability-weighted average count over comparable plans.
Important note
Do not multiply rates from unlike component populations without preserving their separate exposure bases.
Frequently asked questions
Why can expected failures be near one while any-failure probability is only about 63%?
Plans with multiple failures raise the mean, while the any-failure measure only asks whether count is zero or nonzero.
Does detection reduce failure probability?
Not here. It reduces service-impact hours after a failure occurs.
Can I model different component types?
Use separate calculations unless their probabilities and consequences are genuinely comparable.