In determining empty weight for an aircraft under 14 CFR Part 23, what is included?

The empty weight of an aircraft under 14 CFR Part 23 includes several critical components, and one of those components is the oil in the supply tank. Empty weight is defined as the weight of the aircraft with all fixed equipment installed, such as engines, airframes, and other related items, excluding any fuel, passengers, or cargo. This weight measurement is essential for understanding the aircraft's performance and balance characteristics.

In this context, including the oil in the supply tank reflects the standard definition of empty weight as it allows for a precise calculation of the aircraft's weight when no external variables, like fuel, are present. Therefore, oil, which is a necessary operating fluid for the aircraft, forms a part of its empty weight since it affects aircraft performance and operation.

While it may seem intuitive to consider other options, they do not align with the established regulatory definition of empty weight. Installed options and pilot weight do not count towards empty weight since they can vary and often include items outside the fixed equipment. Additionally, no fuel is a critical factor since fuel is explicitly excluded from this measurement, reinforcing the correct understanding of empty weight in aviation.