What is meant by the term 'residual fuel'?

• A. The fuel remaining in the tanks, lines, and engine after draining
• B. The fuel remaining in the tanks after draining
• C. The fuel that cannot be burned
• D. The fuel used in flight

Answer: (B)

Residual fuel is the amount of fuel that remains in the tanks after the fuel system has been drained as far as possible. In weight-and-balance calculations, this defined quantity provides a conservative, repeatable value to use for determining aircraft weight and balance. It specifically refers to fuel left in the tanks; fuel that remains in lines or engine feeds isn’t counted in this standard residual amount. The other ideas—fuel in lines/engine, fuel that cannot be burned, or fuel used in flight—do not fit the established definition and use of residual fuel.