Final answer:
The checklist for shutting down the APU is part of the aircraft's operating procedures, typically indicating the step when it ensures safety and proper equipment management. It must be followed rigorously as part of safety protocols mandated by aviation authorities like the FAA.
Step-by-step explanation:
The checklist an operator or pilot might refer to for shutting down the APU (Auxiliary Power Unit) will typically be part of standardized operating procedures and is used to ensure that all necessary actions are taken for safety and equipment management.
While the specific question about when the checklist indicates the requirement to shut down the APU would depend on the individual aircraft's operating manual or guidelines, the general consideration would focus on safety protocols.
Procedures such as the WHO surgical checklist, and regulations by bodies like the Federal Aviation Administration (FAA), enforce safety measures including operational limits and necessary rest periods for personnel like pilots, highlighting the importance of rigorously following checklists and protocols to reduce workplace accidents and ensure safe operation of equipment.