With EXT PWR ON, External Power is applied to both sides.

With EXT PWR ON, External Power is applied to both sides.

• A. External Power is applied to both sides.
• B. External Power is applied to the left side only.
• C. APU is started automatically.
• D. The APU power source is reconnected.

Answer: (A)

When you set EXT PWR ON, the ground power is connected to the aircraft in a way that feeds both main electrical sides. The external power contactors and bus ties close, so the left and right AC buses are supplied from the external source. This is why external power is applied to both sides rather than just one. The APU behavior is not governed by this switch. EXT PWR ON does not automatically start the APU, nor does it reconnect an APU power source. It simply provides external power to the aircraft’s electrical system on both sides.

When you set EXT PWR ON, the ground power is connected to the aircraft in a way that feeds both main electrical sides. The external power contactors and bus ties close, so the left and right AC buses are supplied from the external source. This is why external power is applied to both sides rather than just one.

The APU behavior is not governed by this switch. EXT PWR ON does not automatically start the APU, nor does it reconnect an APU power source. It simply provides external power to the aircraft’s electrical system on both sides.