What will illuminate if the fuel imbalance is not reduced to less than 30 pounds within 2 minutes?

If the fuel imbalance is not reduced to less than 30 pounds within 2 minutes, the situation will trigger the illumination of the FUEL BAL annunciator. This annunciator is designed to alert the flight crew to the fuel imbalance condition, indicating that the system's automatic fuel transfer may not be functioning as intended, and requires attention.

The primary role of the FUEL BAL annunciator is to provide a visual signal when there is an imbalance in the fuel quantities between the left and right fuel tanks. Fuel imbalances can affect aircraft performance and handling, making it crucial for pilots to address the issue promptly to ensure a balanced and safe flight.

Other annunciators, while related to fuel management, serve different purposes. The FUEL DON annunciator indicates that the fuel dump system is active, the FUEL LO annunciator signals low fuel levels in a tank, and the FUEL PX annunciator indicates low fuel pressure, none of which directly address the specific issue of fuel imbalance that the FUEL BAL annunciator does.