FAA Powerplant Written Practice Test

What is a common sign of piston ring wear during an engine check?

1. Excessive oil consumption

2. Increased fuel flow

3. High manifold pressure

4. Low cooling system pressure

The correct answer is: Excessive oil consumption

Excessive oil consumption is a common sign of piston ring wear during an engine check because it indicates that oil is leaking into the combustion chamber. As piston rings wear down, they lose their ability to create a proper seal between the piston and the cylinder wall. This compromised seal allows oil, which should remain in the crankcase for lubrication, to enter the combustion process instead. The result is that the engine burns more oil than normal, leading to noticeable oil consumption, which can also produce blue smoke in the exhaust as the oil is burned. Other options, like increased fuel flow, high manifold pressure, and low cooling system pressure, are not directly related to piston ring wear. Increased fuel flow could be indicative of a fuel system issue or engine mismanagement but does not directly relate to piston ring integrity. High manifold pressure is usually associated with engine load or performance characteristics rather than wear. Low cooling system pressure typically relates to coolant leaks or failures in the cooling system, rather than to the condition of the piston rings.