How should the bottle select switch be positioned for APU emergency controls?

The bottle select switch should be positioned to "NORMAL" for APU emergency controls because this setting allows the system to operate under normal conditions where the primary control and monitoring of the Auxiliary Power Unit (APU) function properly. In the "NORMAL" position, the system utilizes its standard functions, ensuring that the APU can be monitored and controlled effectively during operations.

This is essential for ensuring that the APU can provide power and bleed air as intended during emergencies. Utilizing the "NORMAL" position allows for the automatic activation of safety protocols and appropriate responses from the APU systems without manual intervention that would be necessary in other switch positions.

Other settings such as "OFF," "FAULT," or "STANDBY" do not facilitate the required functionality of the APU during emergencies, thus supporting the need to select "NORMAL" to assure readiness and responsiveness of the auxiliary system when needed most.