What forms can the action required by an Airworthiness Directive (AD) take?

The action required by an Airworthiness Directive (AD) can take several forms, which is why the selected answer is accurate. An AD is issued to inform aircraft owners, operators, and maintenance personnel of specific issues that could impact the safety of the aircraft. As such, the actions required by an AD can include various responses to address potential safety concerns effectively.

These responses might involve inspections to assess the current state of the aircraft components, parts replacement when a specific part is found to be defective or potentially unsafe, design modifications to improve safety features, or changes in operating procedures to alter how an aircraft is operated in response to the identified safety risk. This comprehensive approach ensures that all aspects of aircraft safety and airworthiness are considered.

The other choices are limited in scope and do not encompass the full range of actions an AD can prescribe. For example, focusing solely on inspection and maintenance records, or parts replacement or design modification alone, fails to recognize that an AD can also mandate changes in operating procedures which are essential for addressing identified risks. The broad range of potential responses allows for flexibility in addressing airworthiness issues, reflecting the complexity and variability of aviation safety measures.