During departure, ACSC switches from APU to Engines when which conditions are met?

• A. Gear Up, Flaps Up, Thrust Levers out of TOGA
• B. Gear Down, Flaps Down, Thrust Levers Idle
• C. Gear Up, Flaps Up, Thrust Levers Idle
• D. Gear Up, Flaps Up, Thrust Levers In TOGA

Answer: (A)

The group of conditions tested is when the aircraft has moved from the takeoff phase into a climb, with the airplane in a clean configuration. The ACSC will switch from using the APU bleed to engine bleed air once the landing gear is retracted, the flaps are up, and the thrust levers are no longer in the TOGA detent. At that point, the engines are producing bleed air and can meet the packs’ needs, so it’s more efficient and reliable to source bleed air from the engines rather than the APU. If any of these conditions aren’t met—gears still down, flaps still extended, or thrust still in TOGA—the system stays on APU bleed to ensure continuous bleed air supply during the critical takeoff and early climb.