Aircraft Ice Detection and De-icing Systems

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Questions and Answers

Stall warning systems provide the crew with a clear and distinctive warning:

After the stall is reached

At all angles of attack

Before the stall is reached (correct)

When an ultrasonic ice detector probe accumulates ice, it vibrates at a:

Higher frequency

Lower frequency (correct)

Constant frequency

The stall identification system contains an actuator that:

Pushes the control column forward

Maintains the angle of attack

Pulls the control column rearward (correct)

When not in use, pneumatic de-icing boots are:

Deflated and kept flush with the airframe Signup and view all the answers

Weeping wing de-icing systems rely on:

Pumping repellent fluid from the reservoir onto the surface Signup and view all the answers

De-icing fluids contain:

Ethylene glycol and additives Signup and view all the answers

Windscreen ice protection:

Relies on an electrical heating element embedded within the glass layers to prevent ice from forming Signup and view all the answers

De-icing:

Allows ice to form, and then be removed on a periodic basis Signup and view all the answers

An angle of attack (AoA) sensor vane aligns itself with the:

Prevailing airstream Signup and view all the answers

When airflow passes over the wing without breaking up, it is said to have a:

Streamline airflow Signup and view all the answers

How is a serrated rod ice detector bench tested?

Motor test and go/no-go gap measurement Signup and view all the answers

Windshield heating provides:

Impact resistance enhancement Signup and view all the answers

At what pressure and temperature is anti-ice fluid applied?

70°C at 100 PSI Signup and view all the answers

The advantage of leading edge fluid de-icing is:

Aerodynamic shape is not disturbed Signup and view all the answers

On large transport aircraft, the windshield wiper system is:

Independent on each side with different power sources Signup and view all the answers

Prior to securing a leading-edge de-icing boot, you must:

Shave rivet to prevent further abrasion Signup and view all the answers

On a 'hot rod' type of ice detector, it is switched on:

When selected by the crew Signup and view all the answers

Ice formation on wings is due to:

Supercooled water changing state on contact with the wing Signup and view all the answers

When a vibrating rod ice detector has de-iced, the warning lamp on the flight deck:

Goes out after one more cycle Signup and view all the answers

De-misting of passenger windows is provided by:

An electrical heating element Signup and view all the answers

A deicer boot is completely bonded to the leading edge to:

Provide smoother airflow over the leading edge Signup and view all the answers

In a cockpit window heater system, the autotransformer:

Supplies AC power for heating Signup and view all the answers

Windshield rain repellent is applied:

Before rain and spread on the window surface by wipers Signup and view all the answers

Pneumatic rain removal systems:

Use engine bleed air at high velocity to remove water droplets from the windscreen Signup and view all the answers

Windshield wiper torque tests are carried out at:

The shaft end Signup and view all the answers

Windscreen autotransformers:

Step up voltage Signup and view all the answers

An ice deposit formed when liquid water flows over the airframe before freezing, and which is dense, tough, and sticks closely to the surface is called:

Glaze Ice Signup and view all the answers

Study Notes

Stall Warning Systems

Stall warning systems indicate to the crew that a stall is imminent and is a critical aspect of flight safety
These systems provide a warning before the stall is reached

Ice Detectors

Ultrasonic ice detectors vibrate at a lower frequency when they accumulate ice

Stall Identification Systems

Stall identification systems contain an actuator that pulls the control column rearward

Pneumatic De-icing Boots

Pneumatic de-icing boots are deflated and kept flush with the airframe when not in use

Weeping Wing De-icing Systems

Weeping wing de-icing systems rely on pumping repellent fluid from a reservoir onto the surface to prevent the buildup of ice

De-icing Fluids

De-icing fluids contain propylene glycol and additives
De-icing is the process of removing existing ice buildup

Windscreen Ice Protection

Windscreen ice protection relies on an electrical heating element embedded within the glass layers to prevent ice from forming
This type of system does not require the use of ice repellent fluids

Angle of Attack (AoA) Sensor Vane

An AoA sensor vane aligns itself with the prevailing airstream

De-icing De-misting

De-icing is the prevention of ice formation
De-misting is the removal of moisture from surfaces such as passenger windows, which is achieved by an electrical heating element

De-icing Boots

De-icing boots are completely bonded to the leading edge to prevent electrical static buildup
When a de-icing boot is fully inflated, it disrupts airflow over the leading edge and can reduce lift

Windshield Heaters

Windshield heater systems utilize an autotransformer to step up output in severe weather conditions

Windshield Rain Repellent

Windshield rain repellent is applied before rain and spread on the window surface by wipers

Pneumatic Rain Removal Systems

Pneumatic rain removal systems use engine bleed air at high velocity to remove water droplets from the windscreen
These systems are not permitted on large transport aircraft, as they may have undesirable effects on aircraft performance
They are commonly used on smaller, general aviation aircraft

Windshield Wiper Torque Tests

Windshield wiper torque tests are carried out at the shaft end

Types of Ice

Glaze ice forms when liquid water flows over the airframe before freezing, resulting in a dense, tough ice deposit that sticks closely to the surface
Rime ice forms when supercooled water droplets freeze on impact with the airframe, and is typically less dense and more porous than glaze ice
Hoar frost forms when water vapor freezes directly onto a surface, leading to a white, feathery ice deposit

Pitot Head Heaters

Pitot head heaters must only be switched on for the minimum time required to check serviceability

Ice Formation on Wings

Ice formation on wings is due to supercooled water changing state on contact with the wing

Vibrating Rod Ice Detectors

When a vibrating rod ice detector has de-iced, the warning lamp on the flight deck goes out after a set period of time

De-icing Boot Securement

Prior to securing a leading-edge de-icing boot, you must shave rivets to prevent further abrasion

Leading Edge De-icing

The advantage of leading edge fluid de-icing is that it does not disturb the aerodynamic shape

'Hot Rod' Type Ice Detectors

'Hot Rod' type ice detectors are switched on when selected by the crew

Windshield Wiper Systems

On large transport aircraft, the windshield wiper system is independent on each side with different power sources
Each side has its own system with its own power source, for reliability and safety reasons

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Description

Explore the critical systems designed for ice detection and de-icing in aviation. This quiz covers stall warning systems, ice detectors, and various de-icing technologies essential for flight safety. Test your knowledge on how these systems operate and ensure safety in icy conditions.