FAA Powerplant Written Practice Test

How is oil collected by the piston oil ring returned to the crankcase?

1. It evaporates naturally

2. Through holes drilled in the piston oil ring grooves

3. By using a suction pump

4. Through a series of ducts

The correct answer is: Through holes drilled in the piston oil ring grooves

The process of oil collection by the piston oil ring returning to the crankcase is effectively facilitated through holes drilled in the piston oil ring grooves. These holes allow excess oil that has been scraped off the cylinder walls by the oil ring to flow back down into the crankcase for recirculation. The design ensures that the oil does not remain on the cylinder walls, where it could cause excessive consumption or lead to carbon buildup. This method promotes efficient lubrication and maintains an optimal oil level within the system, ensuring that the engine operates smoothly. The presence of these strategically placed holes allows gravity to assist in guiding the oil back down, reducing the likelihood of oil starvation and ensuring that the moving parts receive consistent lubrication. While the other methods mentioned in the choices might involve the oil in different contexts, they do not represent the actual mechanism by which oil is returned to the crankcase in this scenario.