If the oil pressure remains between 15 and 40 psi at IDLE for more than 5 seconds, ______ will be illuminated.

When the oil pressure is between 15 and 40 psi at idle for more than 5 seconds, it indicates a potential oil pressure issue that could affect the engine's operation. In the T-6B aircraft, this scenario triggers a warning system designed to alert the pilot to the abnormal condition.

The red OIL PX message signifies a critical and immediate concern regarding oil pressure, indicating that the conditions may pose a serious risk to engine performance. Simultaneously, the yellow (amber) OIL PX message serves as a caution, indicating that while the situation is not immediately critical, it still warrants attention from the pilot.

Since both the yellow and red messages are designed to alert the pilot of varying levels of concern regarding oil pressure, when the oil pressure is in the specified range for an extended time, both messages will illuminate. This dual activation ensures that the pilot is fully aware of the potentially dangerous situation, allowing them to take appropriate action to maintain safety and prevent further complications.