How is APU maintenance tracked on the C-5?

The correct choice is that APU maintenance on the C-5 is tracked using an onboard maintenance management system. This system is designed to efficiently monitor the operational status and maintenance needs of the APU, ensuring that all maintenance activities are logged and tracked in a systematic manner.

This onboard maintenance management system provides real-time data, which assists in scheduling preventative maintenance, tracking usage hours, and ensuring compliance with maintenance protocols. It enhances safety and efficiency by allowing maintenance personnel to access up-to-date information about the APU's performance and any previous maintenance conducted, thereby facilitating informed decisions regarding repairs and inspections.

In contrast, visual inspections alone may not capture all necessary data and could overlook less obvious issues. Relying solely on external maintenance records would leave gaps in tracking and could lead to lapses in timely maintenance. Manual checks by the crew, while helpful for immediate assessments, do not provide the comprehensive overview and systematic tracking required for long-term maintenance management.