What must be done with the BOTTLE SELECT switch during an APU emergency?

In an APU emergency situation, keeping the BOTTLE SELECT switch in the NORM position is crucial. This ensures that the fire suppression system for the APU is activated automatically if a fire is detected. The NORM setting allows the APU to automatically utilize the onboard fire extinguishing agent in the event of an emergency, providing critical protection against fire hazards.

If the switch were turned off or changed to AUTO, it might not function as intended during a crisis. A reset might also lead to a delay in response, which is not advisable in an emergency. Hence, maintaining the switch in the NORM position maximizes the chances of effectively combating a fire and protecting both the aircraft and crew.