Inputs
Fleet and Operations
FH/mo
days
Corrective Maintenance
FH/event
hours
hours
hours/mo
Scheduled + LO + Engines
hours
FH
hours/FH
FH per engine
hours
Results
Per-aircraft availability (A_o)
–
Expected MC aircraft
–
Total downtime per aircraft per month
–
Downtime breakdown (hours per aircraft per month)
A_o ≈ 1 − (total downtime hours per aircraft per month) / (24 × days per month). Events per month for corrective maintenance = FH / MTBM. Engine events per month = FH × engines / engine interval.
Notes and Assumptions
- This is a high-level planning tool; it simplifies real maintenance categories and queueing effects.
- LO downtime is the portion that renders the aircraft non-mission-capable; modern materials/processes can shrink this.
- Logistics delay time (LDT) is often the biggest lever. Reducing LDT (e.g., more spares/depots) raises MC% quickly.
- Defaults reflect a balanced sustainment posture (similar to “Package B”). Use presets to explore tradeoffs.