What condition activates the FUEL BAL annunciator?

• A. Fuel imbalance exceeds 20 lbs for 2 minutes
• B. Fuel imbalance exceeds 25 lbs for 1 minute
• C. Fuel imbalance exceeds 30 lbs for 2 minutes
• D. Fuel imbalance exceeds 35 lbs for 3 minutes

Answer: (C)

The condition that activates the FUEL BAL annunciator is a fuel imbalance exceeding 30 pounds for 2 minutes. This system is in place to alert the crew to a significant discrepancy in fuel quantity between the left and right fuel tanks. Such an imbalance may affect aircraft handling characteristics, fuel distribution, and overall performance.

Monitoring fuel levels is critical for ensuring safety and operational efficiency in flight. The threshold of 30 pounds for 2 minutes serves as a conservative measure to prompt the crew to address the imbalance before it becomes more problematic, allowing for time to initiate corrective actions, such as fuel balancing procedures through crossfeed or adjusting the aircraft's flight profile.

While other options present similar scenarios with different pound thresholds and time frames, they do not align with the specific requirement that activates the FUEL BAL annunciator, which is firmly established in the aircraft's systems and operational procedures.