48 Questions
What is the primary function of the inflatable boots on the leading edges of the wings and stabilizers?
To break away accumulated ice
What is the purpose of the vacuum suction in the deice boot system?
To hold the boots tightly against the aircraft when not in use
What is the typical duration of deice boot inflation?
6 to 8 seconds
What is the source of operating air for deice boot systems in reciprocating engine aircraft?
Dedicated engine-driven air pump
What is the purpose of the suction side of the engine-driven air pump in reciprocating engine aircraft?
To operate the gyroscopic instruments
What is the purpose of the proportioning unit in the chemical deicing system?
To regulate the flow of deicing fluid
What is a benefit of electric deice boots in an aircraft?
They conserve engine bleed air.
What is the purpose of the slip ring and brush assembly in the electrothermal propeller deice system?
To transmit current to the deice boot
What is the result of ice formation on the propeller leading edges, cuffs, and spinner?
Reduced powerplant system efficiency
How do the electric deice boots break off ice particles from the propeller blades?
Through the centrifugal force of the spinning propeller and air blast
What is the purpose of the timer in some electrothermal propeller deice systems?
To control the deice boot sequence
When is the system inoperative in an aircraft with an electric deice system?
On the ground
What is the primary purpose of anti-icing equipment on an aircraft?
To prevent ice from forming on the wings and stabilizers
What is the purpose of deicing equipment on an aircraft?
To remove ice from the wings and stabilizers after it begins to accumulate
What is the most common type of anti-icing system used on general aviation aircraft?
Pneumatic deicing boots
What is the purpose of a weeping wing design on high-performance aircraft?
To prevent ice from forming on the wings
What type of anti-icing system is typically used on large transport-category aircraft?
Thermal pneumatic or thermal electric
What is the primary advantage of thermal pneumatic or thermal electric anti-icing systems over pneumatic deicing boots or chemical anti-ice systems?
They are more effective at preventing ice from forming on the wings
What is the primary function of the deice controller in an electric deice system?
To monitor the temperature and control the de-icing sequence
What is the purpose of the squat switches in an electric deice system?
To monitor the aircraft's airspeed and adjust deice boot operation
What is the primary limitation of pneumatic windshield heat systems in aircraft?
They are not approved for flying into known icing conditions
What is the primary function of a chemical anti-ice system on an aircraft windshield?
To prevent ice from forming on the windshield
What is the primary advantage of electric deice boots over pneumatic deicing boots?
Electric deice boots conserve engine bleed air
What is the primary advantage of electric windshield heat over pneumatic windshield heat systems?
It is more energy-efficient
What is the purpose of the ram air temperature probe in an electric deice system?
To monitor the air temperature and adjust deice boot operation
What is the primary function of the vacuum regulator in a pneumatic deice system?
To regulate the flow of engine bleed air to the deice boots
What is the primary purpose of a spray tube in a chemical anti-ice system on an aircraft windshield?
To distribute the chemical anti-ice fluid evenly
What is the primary function of the low pressure switch in the pneumatic deicing system?
To monitor the air pressure in the tank and prevent over-pressurization
What is the primary source of air for pneumatic windshield heat systems in small aircraft?
The ambient air
What is the primary benefit of automating the deicing process in an electric deice system?
Reduced pilot workload during deicing operations
What is the primary benefit of pneumatic jet blast rain repellent systems on large aircraft?
They provide anti-ice effects
What is the purpose of the filter in the pneumatic deicing system?
To prevent contamination of the air system
How do the deice boots detach from the leading-edge surfaces during deflation?
Through vacuum suction
What is the primary advantage of automating the pneumatic deicing system?
Reducing pilot workload during critical phases of flight
What is the function of the solenoid valve in the pneumatic deicing system?
To regulate the airflow to the deice boots
What is the purpose of the metering pump in the pneumatic deicing system?
To pressurize the air tank
What is the primary function of pneumatic deicing boots on general aviation aircraft?
Removing ice from the wing and stabilizer leading edges
What is the primary purpose of deice control valves in pneumatic deicing systems?
To regulate the flow of air to the deice boots
What is the function of vacuum regulators in pneumatic deicing systems?
To regulate the air pressure to the deice boots
What is the primary advantage of automated deicing systems over manual systems?
Reduced pilot workload
What is the primary difference between pneumatic deicing boots and thermal pneumatic anti-icing systems?
Method of ice removal
What is the primary benefit of thermal pneumatic or thermal electric anti-icing systems over pneumatic deicing boots or chemical anti-ice systems?
Continuous ice protection
What is the recommended method for removing grease and oil from a deicer surface?
Applying a cleaning agent, such as naptha, followed by soap and water scrubbing
What is the purpose of roughening the surface of the deicer before applying a resurfacing material?
To enhance the bonding of the resurfacing material
What is necessary before applying a cold patch repair to a damaged deicer?
Cleaning the area to be patched and buffing to roughen the surface
What controls the operation of electric deice boots on wing sections or on the horizontal stabilizer?
A sequence timer in a deice controller
What is the reason for the boot elements turning ON and OFF in paired sections on electric deice boots?
To avoid aerodynamic imbalance
What is the recommended procedure for all repairs on a deicer?
Following the manufacturer's instructions
Study Notes
Deicing Systems
- GA aircraft and turboprop commuter-type aircraft use pneumatic deicing systems to break off ice after it has formed on leading-edge surfaces.
- The leading edges of wings and stabilizers have inflatable boots attached to them, which expand when inflated by pneumatic pressure, breaking away ice accumulated on the boot.
- Most boots are inflated for 6 to 8 seconds and are deflated by vacuum suction.
- The vacuum is continuously applied to hold the boots tightly against the aircraft while not in use.
Sources of Operating Air
- The source of operating air for deice boot systems varies with the type of powerplant installed on the aircraft.
- Reciprocating engine aircraft typically use a dedicated engine-driven air pump mounted on the accessory drive gear box of the engine.
- The suction side of the pump is used to operate gyroscopic instruments and to hold the deice boots tight to the aircraft when they are not inflated.
Anti-Icing Systems
- Anti-icing equipment is turned on before entering icing conditions and is designed to prevent ice from forming.
- A surface may be anti-iced by keeping it dry, by heating to a temperature that evaporates water upon impingement, or by heating the surface just enough to prevent freezing, maintaining it running wet.
- Deicing equipment is designed to remove ice after it begins to accumulate, typically on wings and stabilizer leading edges.
Wing & Stabilizer Anti-Icing Systems
- Many aircraft make and models have anti-icing systems installed to prevent the formation of ice on wing and stabilizer leading edges.
- The most common anti-icing systems used are thermal pneumatic, thermal electric, and chemical.
- Most general aviation (GA) aircraft equipped to fly in icing conditions use pneumatic deicing boots or a chemical anti-ice system.
- High-performance aircraft may have "weeping wings."
- Large transport-category aircraft are equipped with advanced thermal pneumatic or thermal electric anti-icing systems that are controlled automatically to prevent the formation of ice.
Propeller Deice System
- Deice systems using electrical heating elements and systems using chemical deicing fluid are used to prevent ice formation on propeller leading edges, cuffs, and spinner.
- Electrothermal Propeller Device System uses electrically heated boots on each blade, which receive current from a slip ring and brush assembly on the spinner.
- The centrifugal force of the spinning propeller and air blast breaks the ice particles loose from the heated blades.
Windshield Deice Systems
- Small aircraft may utilize ducted warm air, which is released to flow over the windshield inner surface to defrost and defog.
- Chemical anti-ice systems are used on windshields, where the liquid chemical is sprayed through a nozzle onto the outside of the windshield to prevent ice from forming.
Maintenance and Repair
- Cleaning should be done at the same time the aircraft is washed, using a mild soap and water solution.
- Grease and oil can be removed with a cleaning agent, such as naptha, followed by soap and water scrubbing.
- Resurfacing of the deicer may be necessary when the electrical conductivity of the deicer surface has been destroyed.
- Cold patch repairs can be made on a damaged deicer, following manufacturer's instructions for all repairs.
This quiz covers the components and functionality of pneumatic deicing systems used in general aviation and turboprop commuter aircraft. Learn about the different parts involved in breaking off ice after it has formed, including solenoid valves, pumps, and porous panels. Test your knowledge of aircraft deicing systems and their operations.
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