FAA Powerplant Written Practice Test

What do blue dehydrator plugs indicate when installed on an engine?

1. High humidity present

2. Low humidity with corrosion unlikely

3. Optimal storage conditions

4. Need for immediate inspection

The correct answer is: Low humidity with corrosion unlikely

Blue dehydrator plugs are specifically designed to indicate low humidity levels within the engine, suggesting that the environment is controlled and conducive for storage. When these plugs are inserted into the engine, they absorb moisture, helping to protect the engine components from corrosion and other moisture-related issues. The presence of blue dehydrator plugs indicates that the humidity is low enough to diminish the risk of corrosion, which is particularly important for engines that are not in operation for extended periods. This helps maintain the integrity of the engine's internal components, ensuring that when the engine is needed again, it will perform optimally due to being stored in favorable conditions. In contrast, other options such as high humidity or the need for immediate inspection do not accurately convey the purpose of blue dehydrator plugs, which are specifically intended to confirm safe, low moisture levels for engine storage.