FAA Aviation Mechanic Airframe (AMA)Fuel, Cabin and Ice Control SystemsMedium
A pilot activates the windshield rain repellent system during a heavy rain shower on approach. How does this system improve forward visibility?
- AIt heats the windshield to evaporate rain droplets
- BIt activates high-speed wiper blades synchronized with rainfall intensity
- CIt circulates hot bleed air across the exterior windshield surface
- DIt sprays a chemical fluid that causes rain to bead and blow off in the airstream
Show answer & explanationAnswer & explanation
Correct answer: D. It sprays a chemical fluid that causes rain to bead and blow off in the airstream
Rain repellent systems dispense a small metered charge of chemical fluid onto the windshield exterior; the fluid reduces surface tension so rain forms beads that are quickly swept away by slipstream airflow, improving visibility.
Why the other options are wrong
- A. Evaporation via heat is the function of an electrically heated windshield, a separate system.
- B. Wipers are a separate mechanical system, not part of rain repellent operation.
- C. Hot bleed air is used for anti-icing, not rain repellent function.
Windshield Rain Repellent System
A system that sprays a chemical fluid onto the windshield exterior to cause rain to bead and be removed by airflow, improving visibility in heavy rain.
- Activated by a pilot push-button switch
- Dispenses a metered fluid charge per activation
- Reduces surface tension so rain beads and blows off
Memory trick: Repellent makes rain 'bead and flee' off the glass in the wind.