Which parameters are monitored from the cockpit while the APU is in operation?

The correct choice highlights the critical parameters monitored from the cockpit during APU operation: RPM, temperature, and oil pressure.

Monitoring RPM is essential as it reflects the speed at which the APU operates; maintaining the correct RPM is crucial for optimal performance and longevity. The temperature readings are also vital, as they can indicate the operational state of the APU. High temperatures might suggest potential issues that could lead to failure if not addressed. Moreover, oil pressure is a key indicator of the APU's health, as proper oil pressure is necessary for lubrication and cooling of the internal components, preventing wear and tear.

These parameters allow the flight crew to ensure that the APU is functioning correctly and safely, supporting the operation of essential systems while the aircraft is on the ground or in situations where the main engines are not running. This monitoring is part of a proactive approach to aircraft maintenance and safety, ensuring that any anomalies can be detected early on to prevent larger issues.