FAA Powerplant Written Practice Test

What should be done if small amounts of corrosion prevention compound remain on the cylinder walls after depreserving an opposed cylinder engine?

1. Clean the walls thoroughly

2. Replace the engine

3. Remove all remnants

4. Nothing, small quantities are acceptable

The correct answer is: Nothing, small quantities are acceptable

When dealing with corrosion prevention compounds on cylinder walls after the de-preservation of an opposed cylinder engine, it is generally acceptable to leave small amounts of these compounds in place. These corrosion prevention compounds are designed to protect engine components from moisture and oxidation. If only trace amounts remain, they typically do not pose a risk to engine performance or safety. The presence of small quantities indicates that the protective layer is still functioning to some extent, which might actually be beneficial in preventing further corrosion, especially if the engine is not immediately put to use. It is important to ensure that these remnants do not accumulate excessively, but in this scenario, a minimal presence does not necessitate further action. Cleaning thoroughly may not be necessary unless there is an excessive amount of compound that could interfere with engine operation. Replacing the engine would be an extreme measure, and removing all remnants could lead to unnecessary labor unless there are specific directives calling for complete removal to prevent potential issues. Thus, accepting small quantities as tolerable aligns with good maintenance practices regarding the balance between protection and performance.