When the engine is above idle, a red OIL PX message illuminates when oil pressure falls below what psi?

The correct answer is 40 psi. In the T-6B aircraft, the oil pressure system is designed to monitor the lubrication system of the engine. When the engine is operating above idle, maintaining adequate oil pressure is critical for engine performance and longevity. The red OIL PX warning illuminates when the oil pressure falls below a threshold of 40 psi, indicating a potentially unsafe condition. This precautionary measure serves as an alert for pilots to take immediate action to protect the engine from damage and ensure safe operation.

At oil pressure levels below this prescribed minimum, it could signify inadequate lubrication, leading to increased wear or even failure of engine components. Therefore, a warning light activates at 40 psi to alert the pilot while still allowing for some leeway at idle where oil pressure might fluctuate more naturally. Understanding this threshold is vital in the context of aircraft operation and engine management.