What hard key below FAP must be activated during pre-flight checks?

• A. Lighting
• B. PED Power
• C. Main on/off
• D. Oxygen

Answer: (C)

Power to the Flight Attendant Panel and its related cabin functions must be available during pre-flight checks, and the switch that provides that power is the hard key located below the FAP. Turning this Main on/off switch to ON energizes the cabin electrical system, allowing the FAP indicators to illuminate and enabling checks of the cabin lighting, interphone, and related systems. Without enabling this switch, the FAP cannot be tested or used to perform the pre-flight checks.

The other options are not the action required to energize the FAP for preflight. Lighting is a separate control for illumination, PED Power is about passenger devices, and Oxygen involves the oxygen system itself; none of these provide the necessary power to the FAP needed to complete the pre-flight checks.