Chemical Rain Repellent for Aircraft Windshields: Quiz and Flashcards

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Questions and Answers

What is the primary reason for periodic reapplication of repellent film on aircraft windshields?

To reduce the risk of windshield wiper failure

To enhance the pilot's visibility during sunny conditions

To maintain the windshield's structural integrity

To ensure continued protection against rain impingement (correct)

What is the primary function of the hydrophobic coating on aircraft windshields?

To reduce wind resistance during flight

To improve the windshield's thermal insulation

To increase the windshield's durability against mechanical stress

To cause raindrops to bead up and roll off, reducing distortion (correct)

What is the main advantage of using windshield surface seal coating on aircraft?

Improved windshield durability

Increased windshield wiper effectiveness

Reduced windshield weight

Enhanced pilot visibility during heavy rain (correct)

What is the purpose of applying liquid treatments to the windshield surface?

To maintain the beading action of rainwater on the windshield Signup and view all the answers

What is a characteristic of windshield wipers on aircraft?

They have two basic problem areas Signup and view all the answers

What is one of the main reasons why aircraft wiper systems often fail to provide satisfactory vision in heavy rain?

Slipstream aerodynamic forces reducing wiper blade loading pressure on the window Signup and view all the answers

What is the primary purpose of the heated air flow in the rain removal system shown in Figure 15-43?

To break the rain drops into small particles and heat the windshield Signup and view all the answers

What is the function of the hydrophobic coating on the windshield, as shown in Figure 15-42?

To repel water and reduce streaking on the windshield Signup and view all the answers

What is the purpose of the window anti-icing, deicing, and defogging systems in aircraft?

To keep windshield areas free of ice, frost, and fog Signup and view all the answers

What is the common challenge faced by aircraft wiper systems during heavy rain falls?

Inability to achieve fast enough wiper oscillation to keep up with high rain impingement rates Signup and view all the answers

Under what conditions can ice form on aircraft leading edge surfaces?

On days when there is visible moisture in the air, at altitudes where freezing temperatures start Signup and view all the answers

What is the reason for the unusual occurrence of supercooled water droplets in the air not turning into ice unless disturbed?

The surface tension of the water droplet does not allow the droplet to expand and freeze Signup and view all the answers

What is the characteristic of clear ice on aircraft surfaces?

It is hard, heavy, and tenacious Signup and view all the answers

What is the difference between clear ice and rime ice formation?

Clear ice forms with large water droplets, while rime ice forms with small water droplets Signup and view all the answers

Why does rime ice have a white appearance?

Due to the small frozen droplets trapping air Signup and view all the answers

What is the primary function of the rain repellent system?

To apply a chemical repellent to the windshield in wet conditions Signup and view all the answers

What is the purpose of the time delay module in the rain repellent system?

To meter the repellent to the nozzle Signup and view all the answers

What is the recommended procedure if the rain repellent system is inadvertently operated on dry windows?

Do not operate the windshield wipers or rain clearing system Signup and view all the answers

What is the consequence of not removing concentrated rain repellent or residue from the aircraft skin?

Staining or minor corrosion of the aircraft skin Signup and view all the answers

How many rain repellent units are typically installed on a transport category aircraft?

Two units, one each for the pilot and copilot windshields Signup and view all the answers

What is the purpose of chemical rain repellent in aircraft?

To prevent rain from forming on the windshield Signup and view all the answers

What characteristic is common to windshield wiper systems on some aircraft?

Being operated by separate systems for pilot's and copilot's windshields Signup and view all the answers

What type of surface seal coating is sometimes applied to windshields to remove rain?

Hydrophobic Signup and view all the answers

What is the primary function of pneumatic rain removal systems in aircraft?

To create a pressure difference to remove rain from the windshield Signup and view all the answers

What is the advantage of having separate windshield wiper systems for the pilot's and copilot's windshields?

Ensuring clear vision through one of the windows in case of system failure Signup and view all the answers

Study Notes

Aircraft Rain and Ice Protection Systems

Two major problems with aircraft wiper systems:
- Slipstream aerodynamic forces reduce wiper blade loading pressure, causing ineffective wiping or streaking
- Achieving fast enough wiper oscillation to keep up with high rain impingement rates during heavy rain falls

Windshield Wiper Systems

Typically use electric motors powered by the aircraft's electrical system
Each windshield wiper assembly consists of:
- Wiper blade
- Wiper arm
- Wiper motor/converter
Some aircraft have separate systems for pilot's and copilot's windshield wipers to ensure clear vision in case of system failure

Rain Repellent Systems

Allows application of chemical repellent to windshield by switch or push button in the flight deck
Proper amount of repellent is applied regardless of how long the switch is held
Some systems use a solenoid valve controlled by a time delay module to meter the repellent to a nozzle that sprays it on the outside of the windshield
Should only be used in very wet conditions to avoid restricted window visibility and potential staining or corrosion of aircraft skin

Hydrophobic Coating on Windshields

Causes raindrops to bead up and roll off, allowing for better visibility during heavy rain
Reduces the need for wipers
Typically applied to the external surface of pilot's and copilot's windshields
Manufacturer's coating process deeply penetrates the windshield surface, providing hydrophobic action for a long time
Liquid treatments can be applied periodically to maintain the beading action of rain water

Pneumatic Rain Removal Systems

Use a flow of heated air to break rain drops into small particles that are then blown away
Also heats the windshield to prevent moisture from freezing
Air can be supplied by an electric blower or bleed air

Ice Control Systems

Two types of ice encountered during flight:
- Clear ice: forms when large water droplets flow out over the aircraft surface and freeze as a smooth sheet of solid ice
- Rime ice: forms when small water droplets freeze rapidly on the aircraft surface, trapping air and giving a white appearance
Ice formation can occur at altitudes where freezing temperatures start, especially in cumuliform clouds or light drizzle

De-icing and Defogging Systems

Used to keep windshield areas free of ice, frost, and fog
Can be electric, pneumatic, or chemical depending on the type and complexity of the aircraft

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Description

Learn about the importance of windshield rain repellent and hydrophobic coating in aircraft, including their application and maintenance. Understand how rain intensity and windshield wipers affect the repellent film. Discover the benefits of hydrophobic coating on pilots' and copilots' windshields.

Windshield Rain Repellent and Hydrophobic Coating

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