Which condition is most likely to cause ice on the outside of the fuel tank during flight?

Which condition is most likely to cause ice on the outside of the fuel tank during flight?

• A. Vaporized fuel being drawn instead of liquid fuel
• B. Wind chill causing surface cooling
• C. Condensation from humidity at altitude
• D. Liquid fuel overheating in lines

Answer: (A)

Ice on the outside of the fuel tank during flight is best explained by vaporized fuel being drawn instead of liquid fuel. When fuel is taken as vapor, energy must be consumed to vaporize that fuel, which pulls heat from the surrounding tank and lines. That heat transfer cools the surface of the tank, and if the surface temperature drops below freezing, moisture in the air can freeze on contact, forming frost or ice on the outside. While wind chill or humidity alone can contribute to cold surfaces, the primary mechanism here is the cooling that accompanies vaporization and expansion of the fuel. Overheating liquid fuel would heat rather than cool the surface, so it’s not a plausible cause of exterior ice.

Ice on the outside of the fuel tank during flight is best explained by vaporized fuel being drawn instead of liquid fuel. When fuel is taken as vapor, energy must be consumed to vaporize that fuel, which pulls heat from the surrounding tank and lines. That heat transfer cools the surface of the tank, and if the surface temperature drops below freezing, moisture in the air can freeze on contact, forming frost or ice on the outside. While wind chill or humidity alone can contribute to cold surfaces, the primary mechanism here is the cooling that accompanies vaporization and expansion of the fuel. Overheating liquid fuel would heat rather than cool the surface, so it’s not a plausible cause of exterior ice.