In Aircraft Category Numbers, which item is listed as number 3?

In Aircraft Category Numbers, which item is listed as number 3?

• A. Aircraft
• B. Engines
• C. Propeller
• D. Landing Gear

Answer: (C)

Aircraft Category Numbers organize major subsystems for maintenance reference, with a logical sequence that groups related components together. The propulsion area is split into distinct categories, first the engine itself and then the propeller as a separate item. The propeller is listed after the engine because it is a separate assembly that depends on the engine but is not part of the engine itself, and it has its own inspection and maintenance considerations. The propeller’s role is to convert the engine’s rotational power into thrust, which is why it is categorized separately from the engine. Landing gear appears later in the sequence as part of the distinct structure category. So, the item that occupies that position in the standard order is the propeller.

Aircraft Category Numbers organize major subsystems for maintenance reference, with a logical sequence that groups related components together. The propulsion area is split into distinct categories, first the engine itself and then the propeller as a separate item. The propeller is listed after the engine because it is a separate assembly that depends on the engine but is not part of the engine itself, and it has its own inspection and maintenance considerations. The propeller’s role is to convert the engine’s rotational power into thrust, which is why it is categorized separately from the engine. Landing gear appears later in the sequence as part of the distinct structure category. So, the item that occupies that position in the standard order is the propeller.