Event identity and observation
| Field | Definition and boundary |
|---|---|
| Asset or unit ID | Stable physical tag or serial identity; do not substitute a temporary location alone. |
| Event time | Timestamp with a declared source and time basis; record synchronization uncertainty. |
| Observable symptom | What changed or was detected, without embedding an unverified cause. |
| Operating phase | Controlled state such as startup, acceleration, steady load, transition, shutdown, or idle. |
| Duration | Observed or estimated elapsed time with unit and estimation method. |
| Fault code or alarm | Native displayed or logged value; preserve the original source alongside normalized text. |
| Recovery | Observed return mechanism such as self-clear, reset, power cycle, swap, or still present. |
| Intervention sequence | Ordered actions after the event; distinguish evidence captured before and after each action. |
Context and source evidence
| Field | Definition and boundary |
|---|---|
| Load / operating state | Relevant command, output, duty, mode, and adjacent-system state at the event. |
| Environment | Measured or observed temperature, moisture, contamination, vibration, or other declared condition. |
| Configuration | Hardware, software, firmware, parameter, and installation state needed to compare events. |
| Original evidence | Native log, waveform, trend, photo, video, or witness source with retention location and owner. |
| Evidence gap | A declared missing source; absence must not be silently converted to normal or not applicable. |
Service-history ratios
Target-unit event concentration (%) = target-unit events ÷ all comparable events × 100
The population must be a consistent peer group and period. The ratio is not exposure-normalized unless each unit had equal opportunity.
No-fault-found share (%) = NFF shop outcomes ÷ comparable shop returns × 100
Define NFF from the actual shop process and test coverage. It does not mean “proven serviceable in all operating conditions.”
Symptom recurrence after swap (%) = cases with repeated declared symptom ÷ swaps with adequate follow-up × 100
Keep the symptom definition and follow-up window stable. Recurrence does not by itself locate the fault.
Pattern and reproduction fields
| Field | Definition and boundary |
|---|---|
| Repeated signature | An exact match of normalized phase, code, and recovery in the ReliabilityBench screen; it is an observation cluster, not a causal model. |
| Baseline | Preserved as-found or approved known-good state from which intentional changes are compared. |
| Trigger | One evidence-based condition deliberately staged within approved limits. |
| Instrumentation | Channels, range, sample rate, synchronization, trigger logic, and retained source format. |
| Exposure | Repetitions, dwell, cycles, starts, hours, or other opportunity actually tested. |
| Stop criteria | Preapproved condition requiring the stage to stop or hold. |
| Negative result | Target symptom not observed within the declared conditions and exposure; never equivalent to universal absence. |
| Restoration | Verified return to the approved baseline and separate release-to-service process. |
Decision boundary
Use these fields with approved manuals, safety and energy controls, configuration management, source-data retention, qualified engineering judgment, and accountable release authority. The linked workflow tools organize records; they do not authorize testing or diagnose a cause.