FAA Powerplant Written Practice Test

Why is turbine engine fuel typically maintained above 32°F?

1. To prevent ice crystals from forming and blocking fuel flow

2. To enhance fuel combustion efficiency

3. To maintain consistent fuel density

4. To reduce vapor lock during operation

The correct answer is: To prevent ice crystals from forming and blocking fuel flow

Turbine engine fuel is typically maintained above 32°F primarily to prevent ice crystals from forming and blocking fuel flow. At temperatures around or below this threshold, especially if the fuel has absorbed any water, the risk of ice formation increases. Ice crystals can form from either the water content in the fuel or from condensation within the fuel system. When these crystals develop, they can become dislodged and block fuel filters or injectors, potentially leading to fuel starvation and engine performance issues. Maintaining the fuel temperature above freezing helps to ensure that any moisture present in the fuel remains in a liquid state, thereby minimizing the risk of ice blockage and ensuring a more reliable and safe operation of the turbine engine. This practice is crucial for the dependable function of the fuel system, especially during flight conditions where temperatures can drop significantly.