Which display presents primary engine data such as torque and propeller RPM?

The primary display is responsible for presenting critical flight and engine data that pilots need to operate the aircraft safely and effectively. This typically includes primary engine parameters such as torque and propeller RPM, which are vital for managing engine performance and ensuring the aircraft operates within safe operating limits. By consolidating this essential information into one display, pilots can monitor engine status at a glance, making it easier to make informed decisions during flight.

In contrast, secondary, auxiliary, and diagnostic displays serve different purposes. Secondary displays may provide additional information or backup data but are not the main source for engine data. Auxiliary displays might offer supplementary details about the aircraft's systems or navigation but do not typically prioritize engine metrics. Diagnostic displays are focused on troubleshooting and system checks rather than presenting ongoing operational data. Thus, the primary display is the most suitable choice for conveying crucial engine performance metrics during flight.