Anti-Ice and Deice Systems

[Ref. Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25B Page 7-40, 7-41]

Anti-icing equipment is designed to prevent the formation of ice ;

Deicing equipment is designed to remove ice once it has formed ;

Ice detection lighting may also be installed on some aircraft to determine the extent of structural icing during night flights

The Anti-icing and Deicing systems give different protection to various parts of an aircraft:

  1. leading edge of wing
  2. trailing edge of wing
  3. pitot and static port openings
  4. fuel tank vents
  5. stall warning devices
  6. windshields
  7. propeller blades

 

In general, there are 3 major methods for Anti-ice and Deice functions:

  1. inflatable boots
  2. Thermal (electrically heated elements/direct hot bleed air)
  3. Antifreeze solution

 

Airfoil (wing) Anti-Ice and Deice

  1. Inflatable boots (engine-driven pneumatic pump)
  2. Thermal systems (direct hot air or electrically heated coating)
  3. Antifreeze solution

 

Inflatable deicing boots consist of a rubber sheet bonded to the leading edge of the airfoil. The boots (rubber sheet) is using an engine-driven pneumatic pump to inflates it to provide anti-ice or deice functions. The operations can be in a single cycle or allowed to cycle at automatic, timed intervals.

High performance turbine aircraft often direct hot air (bleed air) from the compressor section of the engine to the leading edge surfaces for anti-ice or deice functions.

Thermal anti-ice system (a.k.a ThermaWing) uses electrically heated graphite foil laminate applied to the leading edge of the wing and horizontal stabilizer. There are two zones of heat application: One zone on the leading edge receives continuous heat; the second zone further aft receives heat in cycles to dislodge the ice allowing aerodynamic forces to remove it.

Antifreeze solution is pumped to the leading edge and weeps out through the holes – this design is known as Weeping wing, which is used to prevent the formation and build-up of ice and is capable of deicing an aircraft. Actually, antifreeze solution chemically breaks down the bond between the ice and airframe, allowing aerodynamic forces to remove the ice.

 

Widescreen Anti-ice

There are two main types:

  1. Alcohol (Antifreeze solution)
    • directs a flow of alcohol to the windscreen
  2. Thermal
    • Small wires or other conductive material is imbedded in the windscreen

 

Propeller Anti-ice

There are two main types:

  1. Alcohol (Antifreeze solution)
    • propellers are equipped with a discharge nozzle pointing toward the root of the blade. Alcohol is discharged from the nozzles, and centrifugal force drives the alcohol down the leading edge of the blade
  2. Thermal
    • “propeller boot” cover inboard and the outboard sections. These boots are imbedded with electrical wires that carry current for heating the
      propeller. However, be noticed that if a boot fails to heat one blade, an unequal blade loading can result and may cause severe propeller
      vibration

 

 

 

Leave a Reply

Your email address will not be published. Required fields are marked *