An airworthiness directive is a legally binding order from an authority requiring inspection, modification or replacement to correct an unsafe condition on specific aircraft, engines or parts. Compliance is mandatory by the stated deadline — an aircraft with an overdue AD is not airworthy.
An Airworthiness Directive (AD) is a legally binding instruction issued by an aviation authority (EASA, FAA or the state of design) requiring action to correct an unsafe condition identified in an aircraft type, engine, propeller or component. ADs specify the affected serial numbers or configurations, the required action — inspection, modification, replacement or operating limitation — and a compliance deadline expressed in calendar time, flight hours or cycles. Some are one-time actions; others are repetitive inspections that recur at fixed intervals.
AD compliance is not optional and not deferrable in the way ordinary defects are: an aircraft with an overdue AD is unairworthy as a matter of law. Operators must evaluate every new AD for applicability to their fleet, schedule compliance within the deadline, and retain evidence of accomplishment for the life of the aircraft.
Why it matters for flight schools
AD management is a continuous monitoring obligation that scales badly on paper. Authorities publish ADs weekly; each must be checked against every airframe, engine and installed component in the fleet — including applicability by serial number and modification state. Missed ADs are among the most serious audit findings a school or CAMO can receive, and they surface at the worst moments: ARC reviews, aircraft sales and insurance investigations.
How FlightLogger handles it
FL Maintenance binds ADs to the specific airframes, engines and components they apply to and tracks compliance deadlines against live hours and cycles — so repetitive inspections resurface automatically and nothing depends on someone rereading last month's AD bulletin.
Frequently asked questions
What is the difference between an AD and a Service Bulletin?
A service bulletin is the manufacturer's recommendation; an AD is the authority's legal mandate. ADs frequently mandate the actions described in a specific service bulletin — turning a recommendation into a requirement with a deadline.
Can an AD deadline be extended?
Only through a formal exemption or alternative means of compliance (AMOC) approved by the authority — not by operator decision. Absent that, flying past an AD deadline makes the aircraft unairworthy.