What happens when the HP1 push button is turned off?

When the HP1 push button is turned off in the Dassault Falcon 2000LXS, it specifically overrides the Bleed Air Supply Control (BASC) system, leading to the closure of the high-pressure bleed valve. The BASC system is designed to automatically manage bleed air operations for optimal efficiency and performance during various phases of flight. By shutting off HP1, the pilot takes manual control, and the bleed valve closes to prevent any further bleed air from being used, which is crucial when trying to manage the aircraft's systems or conserve engine performance under specific conditions.

Automatic regulation and bleed valve operation are dictated by the BASC system when the HP1 button is on or when the system is in its automatic mode. Thus, turning HP1 off shifts the system from an automated state to a manual state to prioritize fuel efficiency or aircraft performance as deemed necessary by the crew.