Answers - Ice & Rain Control


1. airfoils and air inlets
2. moisture, freezing temperatures
3. lighter, of little
4. rime, clear
5. icing, performance, deteriorate
6. thermal, electrical, and chemical anti‐icing systems
7. turbine compressor, engine exhaust heat exchangers, combustion heater
8. computers
9. electric thermal
10. weeping wing
11. pneumatic de‐icing system, leading edge
12. vacuum, suction
13. engine‐driven air pump (vacuum pump), gas turbine compressors
14. electrical boots or chemical de‐ice
15. ice, fog
16. resistance wire, conductive coating
17. ice detector sensors


1. true
2. true
3. true
4. true
5. true
6. false
7. false
8. true
9. false
10. true
11. false
12. true
13. false
14. true
15. true


1. a
2. c
3. b
4. a
5. d
6. a
7. a
8. d
9. c
10. c


1. clear and rime ice

2. a) malformation of the airfoil which could decrease the amount of lift; b) additional weight and unequal formation of the ice which could cause un‐balancing of the aircraft.

3. surge, vibration, and complete thrust loss

4. wing leading edges; horizontal and vertical stabilizer leading edges; engine cowl leading edges; propellers, propeller spinner; air data probes; flight deck windows; water and waste system lines and drains.

5. heat surfaces with hot air; heat with electrical elements; breaking up ice with inflatable boots; chemical spray.

6. wing , leading edge slats, horizontal and vertical stabilizer, engine, and wind shield anti‐ice.

7. to heat both wings equally, keeping the airplane aerodynamically stable in icing conditions.

8. without a forward speed the leading edge can easily overheat if left on, therefore the ground sensing system (weight on wheels) will disable the system.

9. antifreeze solution is pumped from a reservoir through a mesh screen embedded in the leading edges of the wings and stabilizers. Activated by a switch in the cockpit, the liquid flows over the wing and tail surfaces, deicing as it flows.

10. When deice system is energized, the control valves in each nacelle and deflate valve receive power. The deice control valves route pressurized air from the discharge side of the pump to the deicer boots. At 17 psi, pressure switches on the deflate valve will de‐energize the deice control valves, and the boots will be deflated and vacuum pressure will hold the boots down against the leading edge surfaces.

11. a new layer of ice may begin to form on the expanded boots and become un‐removable.

12. large amounts of hot air can be bled off the compressor, providing a satisfactory source of anti‐icing and deicing heat.

13. pumps have carbon vanes and parts that self lubricate.

14. windshield wipers, chemical rain repellent, pneumatic rain removal (jet blast), or the windshields are treated with a hydrophobic surface seal coating.

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