How often does the C-5 APU typically require major overhauls?

The correct answer indicates that the C-5 APU typically requires major overhauls every 3,000 operational hours. This interval is based on the operational factors and maintenance schedules established for the APU, ensuring that it remains reliable and efficient over time. Regular overhauls are critical as they allow for inspection, replacement of worn components, and the performance of necessary adjustments that ensure optimal functioning of the APU.

While the other options suggest different overhaul intervals, they do not align with the established maintenance guidelines for the C-5 APU. Too frequent overhauls, such as every 1,000 or 2,000 operational hours, could lead to unnecessary downtime and higher maintenance costs, while suggesting an overhaul every 5,000 operational hours would exceed the recommended maintenance schedule, potentially risking operational integrity and safety. Adhering to the 3,000-hour mark strikes a balance between reliability and cost-effectiveness in maintaining the APU's performance.