FAA Powerplant Written Practice Test

How are cylinder walls typically lubricated in aircraft engines?

1. By splashed or sprayed oil

2. By oil mist injection

3. By pressure fed oil

4. Using a combination of methods

The correct answer is: By splashed or sprayed oil

Cylinder walls in aircraft engines are typically lubricated by splashed or sprayed oil. This method relies on the motion of various engine components, particularly the connecting rods and pistons, to distribute oil throughout the engine. As the engine operates, the connecting rods can splash oil onto the cylinder walls, ensuring that adequate lubrication is present to reduce friction and wear between the moving parts. This is crucial for maintaining optimal engine performance and longevity. The process of splashing or spraying oil provides a reliable way to achieve effective lubrication without the need for complex systems, making it particularly suitable for many types of aircraft piston engines. The simplicity of this method allows for effective use of engine oil, which is critical for heat dissipation and sealing the combustion chambers. Other methods like oil mist injection and pressure-fed oil systems may also be used in various contexts, but splashed or sprayed oil remains the most common technique in traditional aircraft engine designs for lubricating the cylinder walls. Some engines do use a combination of lubricating methods, but in the context of how cylinder walls are typically lubricated, the splashed or sprayed approach is the standard practice.