Which statement about the ADG deployment scenario is true?

• A. The ADG provides power to the ESS bus when external power is unavailable
• B. The ADG provides power to the ESS bus only when external power is unavailable
• C. The ADG does not affect ACMP 3B pump
• D. The ADG is used for engine start

Answer: (C)

The key idea is that the Air Driven Generator (ADG) is there to supply independent emergency power to the essential bus so critical systems stay alive when normal power sources fail. That emergency power path is limited to the essential systems and does not energize nonessential environmental control components. The ACMP 3B pump is part of the environmental control system and isn’t on the essential bus path energized by the ADG, so deploying the ADG does not affect that pump. Engine starts, on the other hand, are typically handled by other sources such as APU bleed or external power, not by the ADG. So, the statement that the ADG does not affect the ACMP 3B pump is the accurate one.