Private Pilot Stage 2 Practice Test

Empty weight is a critical measurement that includes not only the airframe and powerplant, but also specific fluids and equipment that contribute to the aircraft's total weight. The correct choice emphasizes the inclusion of unusable fuel and undrainable oil, which are essential components for calculating the aircraft's performance and weight limitations.

Unusable fuel refers to the quantity of fuel that cannot be used by the engine due to its location in the fuel tanks, while undrainable oil means the oil that remains in the engine and cannot be completely removed. Both of these items are significant because they contribute to the aircraft's operational capabilities and ensure that the weight is accurately accounted for during pre-flight calculations and weight and balance considerations.

In contrast, the other options either fall short of including all necessary components for an accurate empty weight calculation or include items that do not belong in this specific metric. Understanding what constitutes empty weight is crucial for pilots when planning flights, as it affects performance calculations, fuel requirements, and adherence to weight limits.