MEL Management for Part 135: From MMEL to OpSpec D095 Approval

A Minimum Equipment List allows operators to dispatch aircraft with certain inoperative equipment under defined conditions. Without an approved MEL, any inoperative item grounds the aircraft until repaired.

Your MEL is derived from the Master MEL (MMEL) published by the FAA for each aircraft type. You can be more restrictive than the MMEL but never less restrictive.

Start with the current MMEL for each aircraft type in your fleet. Review each item against your operational profile — routes, weather minimums, passenger configuration, and mission types. Your MEL should reflect how you actually operate.

Common customizations include restricting dispatch with inoperative weather radar for IFR-only operations, removing items not installed on your specific aircraft configuration, and adding operational limitations beyond MMEL minimums.

Submit your MEL package to your Principal Operations Inspector (POI). The package should include your operator MEL document, a compliance matrix showing how each item traces to the MMEL, crew training documentation on MEL dispatch procedures, and maintenance procedures for deferred items.

Approval typically takes 30-90 days. Plan ahead — operating without an approved MEL means any equipment deficiency grounds the aircraft.

Every MEL item has a repair interval category (A, B, C, or D). Category A items must be repaired within the time specified in the MEL. Category B items within 3 calendar days. Category C within 10 calendar days. Category D within 120 calendar days.

Track every open MEL item with date deferred, repair interval deadline, and assigned maintenance provider. A missed MEL deadline is an airworthiness violation — not a paperwork issue.

Cross-reference MEL status with your trip schedule in Navlyt TripDesk to prevent dispatching aircraft with expired deferrals.

Using a MEL that references an outdated MMEL revision. Your operator MEL must be updated when the MMEL is revised.

Missing placards or operational limitations required by the MEL item. Every deferred item has associated crew awareness requirements.

Inadequate maintenance documentation for deferred items — the deferral log should show who deferred, when, the repair interval, and any operational limitations.