What position must the fuel balance switch be in to activate the M FUEL BAL annunciator?

• A. Automatic position
• B. Manual position
• C. Off position
• D. Balanced position

Answer: (B)

The M FUEL BAL annunciator is designed to activate when the fuel balance switch is in the manual position. This means that the system is actively being monitored and adjusted by the pilot, allowing for real-time fuel balancing actions. In this configuration, if there is a discrepancy in fuel levels between the tanks, the annunciator will alert the crew, indicating that corrective actions may be necessary.

When the switch is in the automatic position, the system manages fuel balancing independently, and the crew may not receive immediate alerts for minor imbalances. The off position would disable the system entirely, preventing any fuel management or alerts, while the balanced position indicates that the system has successfully equalized fuel levels, and thus, would not trigger an alert since there is no imbalance to notify the crew about. Therefore, the manual position is the correct choice as it enables the crew to actively monitor and manage fuel distribution, prompting the M FUEL BAL warning when needed.