What does an Airworthiness Directive (AD) signify?

An Airworthiness Directive (AD) is a legally enforceable regulation issued by the aviation authority (such as the FAA in the United States) that mandates specific actions to correct a known safety issue concerning aircraft, parts, or appliances. When an AD is issued, it indicates that there is a potential or existing safety hazard associated with the aircraft or its components that must be addressed to ensure continued airworthiness and safety in operation.

The issuance of an AD stems from findings during safety investigations, service bulletins, or reports of incidents. Compliance with an AD is not optional; it is required for maintaining the airworthiness of the aircraft, and operators must take the necessary action within the specified time frame to remedy the problem. This ensures that safety standards are upheld and helps prevent accidents that may arise from the identified issues.

In contrast, other options such as non-mandatory maintenance recommendations, routine maintenance suggestions, or certifications of airworthiness do not carry the same legal weight or immediate requirement for compliance as an AD.