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Aircraft MEL Calculator

The industry-standard tool for computing MEL (Minimum Equipment List) repair intervals. Ensure regulatory compliance with FAA, EASA, and TCCA deferral periods using the "Day of Discovery" rule.

Expiry Calculator

A
B
C
D

MEL Repair Intervals

The Minimum Equipment List (MEL) allows aircraft operation with inoperative equipment. As per EASA Part-ORO.MLR.105 and FAA AC 120-95A, each item has a repair category.

The "Day of Discovery" Rule

The repair interval begins at midnight following the day the defect was recorded. The actual day it is found is "Day 0".

Pro Tip for AMEs:

Category B, C, and D repair intervals may be extended (MEL Extension) if the operator's manual allows it and the authority is notified or provides concurrence.

Frequently Asked Questions

Category A items must be repaired within the time interval specified in the "Remarks" column (e.g., 2 flight cycles or 48 hours).

It is the calendar day the defect is logged. This day is not included in the interval count; the clock starts at the next midnight.

Yes, most operators can extend B and C intervals once for the same duration with technical justification.

Generally no, as 120 days is considered sufficient, though specific NAA deviations may exist.

The aircraft is unairworthy and cannot fly until the defect is rectified or a valid extension is applied.

Only to equipment required by certification. Non-essential items fall under NEEF categories.

The manufacturer creates the MMEL; the operator tailors the MEL to their fleet (can be more restrictive).

No. Calendar days are 24-hour periods. Flight cycles only apply if specified for Category A items.

Yes, if they are typed and authorized by their Part-145 organization.

(M) are physical maintenance tasks; (O) are operational tasks performed by flight crews.

Generally yes for turbine/large aircraft via an LOA, though small piston aircraft have different rules.