Defects & Parts
The maintenance module tracks failures causally: a defect on a specific part renders equipment inoperative, the inoperative combination is matched against MEL trigger scenarios, and the winning MEL entry decides whether the aircraft dispatches with restrictions or is grounded NO-GO. The next pilot sees the outcome in their dispatch briefing.
Defect → Inoperative part → MEL match → Restriction · Procedure (or NO-GO)
Parts catalog
Backoffice → Maintenance → Parts manages the airline's part catalog. Parts are shared across subfleets — an FMC sits on both the 737-700 and the 737-800. Each part carries:
| Field | Meaning |
|---|---|
| Code / Name / ATA | Identity, e.g. PACK — Air conditioning pack, ATA 21 |
| Installed | Units fitted per aircraft (a 737 has 2 PACKs) |
| Required | Minimum units required for dispatch |
| Mean life (hours) | Expected service life driving the health bar |
| Base failure rate (% / 100h) | Baseline in-flight failure probability |
Every aircraft in an attached subfleet automatically gets one part instance per fitted position. Saving a part resyncs the whole affected fleet asynchronously — newly attached subfleets gain instances on every active tail, detached subfleets and reduced installed counts are pruned (defect history is never touched). Instances also sync after every approved flight, so the per-aircraft "Sync from catalog" button is only a manual fallback. Instances age with real flight hours; health is the remaining share of mean life, and units under 12% life surface as "replace soon".
In-flight failures
After every approved flight the aircraft's part instances age by the flown hours and one age-weighted failure roll runs: a brand-new part fails at half its base rate, a part at mean life at twice. A failure files an open defect (source: In-flight) on the triage board — nothing is grounded or restricted until staff disposition it.
Defects triage board
Backoffice → Maintenance → Defects is a four-column board: Open, Deferred · MEL, NO-GO and Rectified. Open defects (from pilots, staff, FDM events or in-flight failures) await a disposition:
- Defer — matches the aircraft's inoperative parts against the MEL library and defers under the winning entry: the MEL item activates (dispatch penalties apply to SimBrief immediately), and the repair category sets the rectification deadline (Cat A = its hour interval, B = 3 days, C = 10 days, D = 120 days). If nothing matches, the defect is deferred as informative.
- NO-GO — grounds the aircraft: all bookings are cancelled, new bookings are blocked, staff are notified on Discord.
- Rectify — clears the defect and lifts its restrictions. Clearing the last NO-GO defect returns the aircraft to service automatically — unless an overdue or in-progress maintenance check still holds it down.
The Raise defect wizard walks through part and position selection, reviews the projected inoperative equipment, and previews the MEL match — including the NO-GO warning — before anything is filed.
MEL trigger scenarios
Each MEL definition can carry trigger scenarios: combinations of parts and quantities that resolve to it. One PACK inoperative and both PACKs inoperative are distinct entries — when several scenarios fire at once, the most specific match wins (the one demanding the most inoperative units). A definition flagged NO-GO grounds the aircraft the moment its scenario becomes active.
Scenarios are managed on the MEL definition editor, alongside the existing dispatch penalties and (O)/(M) procedure documents. MEL activation is exclusively defect-driven — there is no random per-booking activation and no manual activation. Deferred items past their repair-category deadline go overdue (surfaced on the board and briefing) and wait for the virtual mechanics (Maintenance → Settings): Defect Auto Rectify (default On) resolves deferred defects once their scheduled resolve-by date arrives, and No Go Repair Hours gives NO-GO defects a repair ETA after which the aircraft returns to service automatically. Mechanics never touch a tail with an unexpired booking — everything waits until the booking expires. Rectifying a defect always renews the failed part instance, so an aged unit doesn't immediately fail again.
Pilot briefing preview
Backoffice → Maintenance → Briefing Preview renders exactly what the next pilot sees for a tail: a GO / NO-GO verdict, the deduplicated operating-limits strip, and one card per active MEL grouping the affected equipment with its category deadline, dispatch restrictions and the snapshotted operational procedure.