What mechanism prevents oil from draining into the accessory gearbox in a dry sump engine?

The mechanism that prevents oil from draining into the accessory gearbox in a dry sump engine is the anti-static check valve between the oil pump and sump. This check valve is designed to allow oil to flow from the sump to the oil pump while preventing any backflow that could occur due to gravity when the engine is not running.

In a dry sump engine, the oil is stored in a separate tank, and the oil pump is responsible for drawing oil from this tank and delivering it to various engine components. Once the oil is pumped throughout the system, the check valve ensures that any pressure in the line keeps the oil from migrating back into the accessory gearbox. This is crucial because it helps maintain the separation of the oil system from the gearbox, thereby protecting the engine's operational integrity and preventing any potential contamination or operational issues that could arise if oil accumulated in the gearbox.

The other options relate to different functions or mechanisms that are not specifically designed for preventing oil from draining into the accessory gearbox. An oil pressure relief valve regulates oil pressure but does not create a barrier against backflow. A gravity drain system, as its name suggests, works based on gravitational forces and would not effectively prevent backflow. A mechanical seal serves to prevent leaks between rotating and stationary parts but