Airframe Ice and Rain Control

Question 1

What controls the temperature in a thermal anti-icing system?

Answer 1

Hot and cold air are mixed

Question 2

What are the sources of heat for thermal anti-icing systems?

Answer 2

Bleed air from the compressor section of a turbine engine, engine exhaust heat exchangers and combustion heaters.

Question 3

What prevents overheating of the leading edges of a thermal anti-ice system operated by engine bleed air?

Answer 3

Overheat sensors signal the anti-icing valves to close and shut off the hot air.

Question 4

What happens to the hot air used by a thermal anti-ice system after it has heated the surface?

Answer 4

The air is dumped overboard.

Question 5

Why is it necessary to provide overheat protection for anti-icing systems that use turbine engine bleed air?

Answer 5

The air is hot enough to cause damage to the aircraft structure.

Question 6

What are the effects of arcing on an electrically heated windshield?

Answer 6

Localized overheating and damage to the windshield.

Question 7

Can the operation of an electrically heated pitot-tube be checked with the aircraft’s ammeter, and if so, how?

Answer 7

Yes, turn the pitot heater on and observe the deflation of the ammeter needle.

Question 8

Describe several potential problems associated with electrically heated windshields.

Answer 8

Arcing, delamination, scratches, and discoloration

Question 9

Why do some pneumatic deicer boot systems have an electrically operated timer?

Answer 9

To automatically cycle the boots, provide the proper rest time, and then recycle the boots.

Question 10

What are the two common methods of inflating pneumatic deicer boots?

Answer 10

Bleed air from a turbine engine or the exhaust from an engine-driven vacuum pump.

Question 11

What procedure is used to hold deicer boots flat with the airfoil surface during flight?

Answer 11

Suction is applied to the boots.

Question 12

Why do some deicer boot systems incorporate an oil separator?

Answer 12

If a wet pump is used, the oil must be removed before it reaches the boots because oil damages the rubber.

Question 13

What methods are used to attach a deicer boot to the leading edges of the wing and tail surfaces?

Answer 13

Adhesives, fairing strips and screws, or a combination of both.

Question 14

What important step should be taken prior to making a cold-patch repair to a deicer boot?

Answer 14

Consult the manufacturer’s service manual and follow the repair instructions explicitly.

Question 15

Describe the methods commonly used to remove rain from a windshield.

Answer 15

Windshield wipers, a blast of air, or chemical rain repellent.

Question 16

What power sources are used to operate windshield wipers?

Answer 16

Electricity or hydraulic pressure.

Question 17

Name two problems associated with in-flight operation of aircraft windshield wipers.

Answer 17

Insufficient blade pressure caused by aerodynamic forces and failure to oscillate fast enough.

Question 18

Describe the operation off a pneumatic rain removal system.

Answer 18

A high velocity air blast prevents the rain from reaching the surface of the windshield.

Question 19

What are the effects of spraying rain repellent on a dry windshield?

Answer 19

It smears and streaks, which reduces visibility, and it is hard to remove when dry.

Question 20

Where would you find information on the acceptable limits of windshield delamination?

Answer 20

In reference material provided by the manufacturer.