Which two conditions must be true for ADG deployment?

Which two conditions must be true for ADG deployment?

• A. Weight off wheels and loss of all AC power
• B. Weight on wheels and loss of hydraulic power
• C. Loss of all DC power and pressurization loss
• D. Engine fire

Answer: (A)

ADG deployment is an emergency power action that is designed to activate only when the aircraft is not on the ground and there is a complete loss of AC electrical power. Being weight off wheels means the airplane is airborne, while loss of all AC power signals that the main electrical sources are unavailable, so a dedicated emergency source must come online to keep essential systems powered. This combination prevents the ADG from deploying on the ground or in partial power-loss situations, and ensures it provides power only when truly needed in flight. If the aircraft is on the ground, the ADG should not deploy even if AC power is lost, and other sources or procedures handle ground power. The other options don’t fit because they either involve the aircraft’s status on the ground, focus on hydraulic or DC power rather than AC, or relate to conditions (like an engine fire) that don’t trigger the emergency generator.

ADG deployment is an emergency power action that is designed to activate only when the aircraft is not on the ground and there is a complete loss of AC electrical power. Being weight off wheels means the airplane is airborne, while loss of all AC power signals that the main electrical sources are unavailable, so a dedicated emergency source must come online to keep essential systems powered. This combination prevents the ADG from deploying on the ground or in partial power-loss situations, and ensures it provides power only when truly needed in flight.

If the aircraft is on the ground, the ADG should not deploy even if AC power is lost, and other sources or procedures handle ground power. The other options don’t fit because they either involve the aircraft’s status on the ground, focus on hydraulic or DC power rather than AC, or relate to conditions (like an engine fire) that don’t trigger the emergency generator.