FAA Powerplant Written Practice Test

What is always the final step when degreasing a metal engine part with a soap and water solution?

1. Wipe the part dry

2. Respray the part with oil

3. Soak the part in water

4. Apply a rust inhibitor

The correct answer is: Respray the part with oil

The final step when degreasing a metal engine part with a soap and water solution is to respray the part with oil. This step is crucial because after cleaning, the metal surface can become exposed to moisture and air, which may lead to corrosion. By applying a protective layer of oil, you create a barrier that helps prevent rust and oxidation, preserving the integrity of the metal part. The oil serves as a lubricant and a protective coating until the engine part can be installed or put to operational use. Without this step, the cleaned part is vulnerable to environmental factors that can deteriorate its quality over time. In situations where engine parts must be stored or remain unused for a while, this oil spray acts as a safeguard against rust formation.