FAA Aviation Mechanic Airframe (AMA)Fuel, Cabin and Ice Control SystemsEasy
During a preflight in freezing rain, a pilot activates the windshield anti-icing fluid system on a light twin. How does this system primarily prevent ice accumulation on the windshield?
- AIt circulates hot engine bleed air between two windshield panes
- BIt activates a high-speed wiper blade system that mechanically removes ice buildup
- CIt energizes an electrically conductive film embedded in the windshield to generate heat
- DIt sprays an isopropyl alcohol-based fluid onto the windshield surface to depress the freezing point of moisture
Show answer & explanationAnswer & explanation
Correct answer: D. It sprays an isopropyl alcohol-based fluid onto the windshield surface to depress the freezing point of moisture
Fluid-type windshield anti-icing systems dispense an isopropyl alcohol-based fluid over the windshield; the fluid mixes with moisture and lowers its freezing point, preventing ice formation and improving visibility.
Why the other options are wrong
- A. Describes bleed-air windshield heat, a different anti-ice method.
- B. Wipers remove precipitation mechanically but do not prevent ice formation chemically.
- C. Describes electrically heated windshields, not the fluid system.
Windshield Anti-Ice Fluid System
A system that sprays isopropyl alcohol-based fluid onto the windshield to prevent ice and frost formation by lowering the freezing point of surface moisture.
- Uses alcohol-based fluid, often isopropyl alcohol
- Fluid is pumped from a reservoir to spray bars at the windshield base
- Alternative to electric or bleed-air heated windshields
Memory trick: Alcohol lowers the freeze point, like antifreeze on glass.