FAA Powerplant Written Practice Test

What does the blue color of dehydrator plugs indicate?

1. High humidity with corrosion likely

2. Low humidity with corrosion unlikely

3. Normal engine usage conditions

4. Required maintenance needed

The correct answer is: Low humidity with corrosion unlikely

The blue color of dehydrator plugs indicates low humidity with corrosion unlikely. Dehydrator plugs are used in aviation engines to absorb moisture and prevent corrosion when the engine is not in use. The blue color serves as a visual indicator to show that the plug is functioning effectively. When the humidity is low, it suggests that the environment is less conducive to corrosion, which is crucial for maintaining the integrity of engine components over time. This helps technicians assess the condition of the engine and the effectiveness of the dehydrator plug without needing to conduct further tests. The presence of blue indicates that the protective measures in place are working as designed, allowing for peace of mind regarding potential corrosion issues.