FAA Powerplant Written Practice Test

Which substance is commonly used in propeller fluid anti-icing systems?

1. Glycol

2. Isopropyl alcohol

3. Water

4. Diesel fuel

The correct answer is: Isopropyl alcohol

Isopropyl alcohol is commonly used in propeller fluid anti-icing systems due to its effective properties as a de-icer and anti-icer. It has a low freezing point, helping to prevent the formation of ice on propeller blades during flight in icy conditions. The rapid evaporation of isopropyl alcohol also allows it to be efficient in removing ice quickly, making it suitable for this application. In contrast, while glycol can serve as an anti-icing agent in some situations, it is typically used in other contexts, such as in de-icing fluids for aircraft surfaces rather than specifically within propeller fluid systems. Water, although essential in many applications, does not possess the necessary antifreeze properties to prevent ice formation effectively in aviation applications. Diesel fuel, primarily used for engine operation, does not have any anti-icing characteristics, rendering it unsuitable for this purpose.