Which of the following is true regarding the standby fuel pump?

The standby fuel pump is designed to serve as a backup to the main fuel pump and plays a critical role in ensuring the fuel system's reliability and functionality. When considering its operation, one significant aspect is its engagement during crossfeed operations. Crossfeed refers to the ability to draw fuel from various tanks to ensure the aircraft can maintain fuel flow and balance.

For effective crossfeed, the standby fuel pump must be off to prevent any potential interference with the main fuel pump's operation. Engaging the standby pump could create pressure conflicts or flow issues, ultimately compromising the system's efficiency and safety.

While the standby fuel pump does have specific scenarios where it is necessary, such as providing additional fuel flow if the main pump fails, it is not essential to propulsion under normal circumstances, particularly when the main fuel pump is functioning properly. Hence, the notion that the standby pump must be off during crossfeed accurately reflects its operational requirements and the system's overall design.