How frequently should the APU oil typically be changed?

The correct answer regarding the frequency of APU oil changes is based on standard maintenance practices for the C-130J's Auxiliary Power Unit (APU). Typically, the oil in the APU should be changed every 500 hours of operational use. This maintenance schedule is established to ensure optimal performance and longevity of the APU. Regular oil changes are essential as they help maintain proper lubrication and reduce wear on engine components, thereby preventing potential failure and ensuring reliability during operations.

While other options suggest longer intervals, such as 1000 or 1500 hours, adhering to the 500-hour mark helps to mitigate risks associated with oil degradation and contamination that can occur over time based on the operational environment and APU usage. Regular oil changes are a critical aspect of the overall maintenance strategy, promoting safety and effectiveness in aircraft operations.