Definition
A legally binding order issued by the FAA requiring the inspection, repair, modification, or operational limitation of an aircraft, engine, propeller, or appliance when an unsafe condition has been identified that is likely to exist or develop in other items of the same design. Compliance with all applicable ADs is mandatory before further flight, or within the timeframe specified in the directive.
Plain English
An official FAA order that says: 'A safety problem has been found on this type of aircraft or part. Here is what you must do about it, and by when.' Owners and operators have to follow it — it is not advice.
Context Anchor
Seen in aircraft maintenance records, aircraft logbooks, inspection paperwork, and discussions about whether an aircraft is legal to fly.
Derivation
Airworthy' means fit and safe to fly — the aircraft conforms to its approved design and is in condition for safe operation. A 'directive' is an authoritative instruction that must be followed. Together, an Airworthiness Directive is a binding instruction to keep the aircraft safe to fly.
Why Pilots Care
Compliance is mandatory; an unaddressed AD can render the aircraft unairworthy and expose the owner to enforcement action or insurance issues.
Intuition Check
An AD is not just a recommendation or maintenance tip. If it applies, it is a mandatory safety requirement.
Example Sentence 1
Before signing off the annual inspection, the mechanic reviewed the aircraft's records to confirm every applicable AD had been complied with.
Example Sentence 2
The owner scheduled the required inspection after receiving notice of a new airworthiness directive affecting the engine.