Which statement accurately describes the effects of additives and impurities on fuel systems?

Which statement accurately describes the effects of additives and impurities on fuel systems?

• A. Impurities can harm fuel pumps and filters; FSII can prevent icing in the airframe fuel system, engine filter, or engine fuel control.
• B. FSII increases fuel density.
• C. FSII raises the flash point.
• D. FSII decreases energy content.

Answer: (A)

Additives and impurities directly affect how reliably a fuel system operates. Impurities such as dirt and water can cause wear on pumps and clog filters, which can lead to restricted flow or fuel starvation. A fuel system icing inhibitor is added specifically to prevent icing within the fuel system, protecting the airframe fuel system, engine filters, and engine fuel control. It does this by keeping small amounts of water dissolved and lowering the freezing point of water in the fuel, so ice doesn’t form and block passages in cold conditions. This icing-prevention role is the key point. The other statements aren’t correct descriptions of FSII: it isn’t used to increase fuel density, it doesn’t raise the flash point, and it doesn’t serve to increase energy content (and may even have the opposite effect in some respects).

Additives and impurities directly affect how reliably a fuel system operates. Impurities such as dirt and water can cause wear on pumps and clog filters, which can lead to restricted flow or fuel starvation. A fuel system icing inhibitor is added specifically to prevent icing within the fuel system, protecting the airframe fuel system, engine filters, and engine fuel control. It does this by keeping small amounts of water dissolved and lowering the freezing point of water in the fuel, so ice doesn’t form and block passages in cold conditions. This icing-prevention role is the key point. The other statements aren’t correct descriptions of FSII: it isn’t used to increase fuel density, it doesn’t raise the flash point, and it doesn’t serve to increase energy content (and may even have the opposite effect in some respects).