FAA Powerplant Written Practice Test

What does corrosion in engine cylinders primarily result from?

1. Long-term exposure to excessive heat

2. Moisture buildup when engines are not flown regularly

3. Improper oil levels during storage

4. Inadequate fuel quality used in operation

The correct answer is: Moisture buildup when engines are not flown regularly

Corrosion in engine cylinders is primarily a result of moisture buildup, especially when engines are not flown regularly. When an aircraft is not in operation, the internal components, including the engine cylinders, can become susceptible to moisture accumulation. This moisture can originate from humidity in the air, condensation, or any residual fuel and oil that may be present. Over time, the presence of moisture can lead to chemical reactions that result in corrosion, particularly if the moisture is not able to evaporate due to the engine being inactive. The effects of corrosion can be severe, as it can compromise the integrity of the metal components, leading to reduced performance, increased wear, and potential failure. This is why proper maintenance practices, including regular operation of the engine and measures to control humidity and moisture levels, are critical for preserving engine health. The other options do not directly cause corrosion in the same way that moisture does. While excessive heat, improper oil levels, and inadequate fuel quality can lead to engine issues such as overheating, engine wear, or deposits, they do not primarily contribute to corrosion in engine cylinders like moisture buildup does.