MEL Calculator for Aircraft Maintenance Deferrals

Calculate the expiry date for MEL (Minimum Equipment List) deferrals based on repair categories A, B, C, and D. Compliant with FAA §121.625, EASA AMC 20-6, and ICAO guidance for aircraft maintenance engineers and operators.


MEL Deferral Calculator

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MEL Repair Categories & Time Limits

As defined by civil aviation authorities (FAA, EASA, Transport Canada), MEL repair categories specify the maximum allowable time to defer inoperative equipment:

Category A
Repaired within the time specified in the MEL remarks (e.g., before next flight, within 24h).
Category B
Repaired within 3 consecutive calendar days, excluding the day the defect was logged.
Category C
Repaired within 10 consecutive calendar days, excluding the day the defect was logged.
Category D
Repaired within 120 consecutive calendar days, excluding the day the defect was logged.

Source: FAA AC 120-95A, EASA AMC20-6.


Frequently Asked Questions

No. Per FAA and EASA guidance, the repair period begins the day after the defect is recorded in the maintenance log.

Yes — with operator approval and regulatory concurrence (e.g., FAA OpsSpec, EASA deviation), Category D items may be extended beyond 120 days.