What bleed air is used to pressurize the fuel tanks?

The correct answer is that bleed air from both the #1 and #3 engines is utilized to pressurize the fuel tanks in the Dassault Falcon 7X. This is an important functionality because pressurizing the fuel tanks allows for the efficient delivery of fuel to the engines, particularly at high altitudes where fuel tank pressure must be maintained for optimal fuel feed to the engine.

The use of bleed air from multiple engines provides redundancy and reliability. By using bleed air from both the #1 and #3 engines, the aircraft ensures that if one engine's bleed air system were to experience an issue, there is still a backup available from the other engine. This dual-engine bleed air system helps maintain fuel availability under varying flight conditions, promotes operational safety, and enhances overall aircraft performance.

It's essential to understand that relying on only one engine’s bleed air could introduce vulnerabilities in the system. Therefore, using bleed air from both designated engines bolsters the fuel pressurization process and adds to the aircraft’s resilience during flight operations.