What was the certification status of aircraft before FAR 23 effective date?

The certification status of aircraft before the effective date of FAR 23 is that they did not include engine oil in the empty weight. This distinction is important because the definition of empty weight specifically pertains to the constructed weight of the aircraft without any operational fluids, which include oil. Therefore, when examining empty weight, it reflects the weight of the aircraft minus the engine oil that would typically be accounted for when the aircraft is ready for flight.

Understanding this context is crucial for recognizing how regulatory standards have evolved. Prior to the enactment of FAR 23, different interpretations may have existed regarding what constituted empty weight, influencing the design and certification process for aircraft at that time. The focus on not including engine oil provided clarity to weight calculations for regulatory compliance and the certification environment, ensuring uniformity in assessing the weight of aircraft against safety standards and operational performance.