Which of the following statements about the Airworthiness Directive (AD) System is true?

• A. Propellers are included in the Airworthiness Directive System.
• B. Propellers are NOT included in the Airworthiness Directive System.
• C. ADs do not apply to propellers under any circumstances.
• D. Propellers must be replaced every year under an AD.

Answer: (B)

Airworthiness Directives address unsafe conditions in aircraft and their parts, and the scope includes propellers along with aircraft and engines. Because propellers are a critical component, they can be the subject of an AD, requiring actions such as inspections, repairs, modifications, or replacement when a safety issue is identified. There isn’t a universal rule to replace something every year; the required action depends on the specific defect and the risk it poses. So propellers being included in the AD system is true, while saying they’re not included or that they must be replaced annually isn’t correct.