What is the difference between total fuel and total usable fuel?

What is the difference between total fuel and total usable fuel?

• A. 0.4 US GAL
• B. 0.5 US GAL
• C. 0.6 US GAL
• D. 0.7 US GAL

Answer: (B)

The difference between total fuel and total usable fuel is the unusable fuel in the system—the amount that cannot be drawn from the tanks into the engine regardless of how you lean or maneuver. Total fuel is simply what the tanks can hold, while total usable fuel is what you can actually burn before fuel flow would be interrupted. For the DA20-C1, that unusable portion is 0.5 US gallons (about 1.9 liters). So, the usable fuel you can rely on in flight is the total fuel capacity minus 0.5 US gallons. That’s why the correct difference is 0.5 US gallons.

The difference between total fuel and total usable fuel is the unusable fuel in the system—the amount that cannot be drawn from the tanks into the engine regardless of how you lean or maneuver. Total fuel is simply what the tanks can hold, while total usable fuel is what you can actually burn before fuel flow would be interrupted.

For the DA20-C1, that unusable portion is 0.5 US gallons (about 1.9 liters). So, the usable fuel you can rely on in flight is the total fuel capacity minus 0.5 US gallons. That’s why the correct difference is 0.5 US gallons.