What should an owner or operator know about Airworthiness Directives (AD's)?

• A. They Are Mandatory
• B. They Are Optional
• C. They Apply Only to Large Aircraft
• D. They Are Published by Manufactures

Answer: (A)

Airworthiness Directives are official safety orders from the aviation authority that require action to fix an unsafe condition on an aircraft, engine, propeller, or related part. They are mandatory, not optional, and must be followed within the specified timeframe in order to legally operate the aircraft. An AD tells you exactly what needs to be done—such as inspections, modifications, or part replacements—and may include acceptable alternatives if approved by the authority.

These directives can apply to a specific model or a particular component, and they can affect small general aviation aircraft as well as large transports. Some ADs are emergency and must be acted on immediately; others give a window for compliance. Importantly, the AD is issued by the aviation authority (such as the FAA in the United States) rather than by the manufacturer, though manufacturers may propose actions that lead to an AD.

So the best interpretation is that Airworthiness Directives are mandatory requirements aimed at correcting unsafe conditions, with defined steps and compliance timelines.