What is the amount of fuel used for computing empty weight and corresponding CG?

The amount of fuel used for computing empty weight and the corresponding center of gravity (CG) is based on the unusable fuel. Unusable fuel refers to the quantity of fuel that cannot be used by the aircraft's engines and is typically retained in the tanks due to design features such as the shape of the fuel tanks and the location of the fuel pickups.

When calculating empty weight, the focus is on determining the minimum weight of the aircraft without any usable fuel, cargo, or passengers. Since the unusable fuel remains in the aircraft at all times, it is included in the empty weight calculation. Consequently, when computing the CG, the effects of this unusable fuel on the overall weight and balance of the aircraft are taken into account.

Using other types of fuel quantity, such as total fuel in the tanks or usable fuel, would not accurately reflect the empty weight category as those amounts can fluctuate with the operational fuel load intended for flight. Evaluating only unusable fuel ensures that the calculation provides a true representation of the aircraft’s weight and balance when it is not intended for flight.