FAA Powerplant Written Practice Test

What type of lubricating systems do aircraft reciprocating engines typically use?

1. Splash type only

2. Gravity type only

3. Pressure type or a combination of pressure and splash type

4. Filtered type only

The correct answer is: Pressure type or a combination of pressure and splash type

Aircraft reciprocating engines commonly utilize either a pressure type lubrication system or a combination of pressure and splash type systems for several important reasons. The pressure type lubrication system delivers oil directly to the moving parts under pressure, ensuring that essential components such as bearings, camshafts, and connecting rods receive a sufficient and consistent supply of oil. This is crucial for maintaining lubrication during high-speed operations and under varying engine loads. On the other hand, splash lubrication, which relies on the motion of engine components to distribute oil, often complements pressure systems. In this setup, oil is splashed onto components by moving parts such as the connecting rods, providing an additional layer of protection against wear. This combination allows for effective lubrication across a wide variety of operating conditions and helps to minimize friction and improve engine longevity. While some engines may use splash or gravity systems alone, they do not provide the reliability and coverage needed for the diverse configurations and operational stresses that reciprocating engines typically face. Consequently, the pressure type or the combination of pressure and splash is the preferred approach, ensuring efficient and effective lubrication across all engine components.