What occurs on the primary engine data displays during abnormal engine operation?

During abnormal engine operation, the primary engine data displays on the T-6 aircraft change color to indicate a malfunction or a deviation from normal operating parameters. This color change serves as a crucial visual alert for the pilot, allowing for immediate recognition of an abnormal condition. Different colors can signal varying levels of severity, helping the pilot assess the situation quickly and take appropriate action.

In contrast, while audio alerts and flashing displays may also signal issues in certain systems, for the primary engine data displays specifically, the color change is the primary method of conveying abnormal conditions. A blank display would not provide any information about the engine's status, and thus, it is not the correct indication for abnormal engine operation.