What fuel remaining in the supply tanks does the LOW FUEL warning come on?

• A. 10 lb
• B. 53 lb
• C. 100 lb
• D. 25 lb

Answer: (B)

Fuel management uses a warning that fires when the fuel in the supply tanks reaches a minimum level that still lets the engines be fed and gives time to react (switch tanks, descend, or land). For this system, the LOW FUEL warning is set at about 53 pounds in each supply tank. That threshold is chosen so you have enough reserve to continue the flight safely and handle transfers or engine feed without risking starvation. Values like 10 or 25 pounds would come on too early, 100 pounds would be too late to alert you in time. Hence 53 pounds is the appropriate, specified trigger.