Which of the following is NOT a form of action required by an AD?

An Airworthiness Directive (AD) is a regulatory notice issued by aviation authorities to address safety issues related to aircraft and aircraft components. The goal of an AD is to ensure that adherence to specific actions will maintain or enhance safety standards across particular aircraft or components.

The correct response indicates that a major structural redesign is not typically required action under an AD. Instead, ADs usually mandate actions that are more direct and practical in nature for the maintenance or repair of existing aircraft or components. These may include inspections, which are routine and necessary for identifying potential issues; part replacements, which are often straightforward and facilitate continued operation; and changes in operating procedures, which may enhance safety without significant alterations to the aircraft itself.

In contrast, a major structural redesign would imply significant changes and alterations to the aircraft’s design or framework, which goes beyond the scope of what an AD is meant to address. ADs focus on immediate safety concerns and corrective actions rather than extensive redesign efforts, which would likely require a more comprehensive regulatory examination and may not be feasible or practical in the context of existing operational aircraft.