Jeppesen Oral- Chapter 13 ( Airframe Ice and Rain Control)

Question 1

Why is it important that ice not be allowed to build up on airplane wings in flight?

Answer 1

Ice distorts the shape of the airfoil and destroys the aerodynamic lift. The weight of the ice loads the aircraft down.

Question 2

Are pneumatic deicer boots operated before ice forms or after it has formed?

Answer 2

Pneumatic deicer boots are not operated until ice has formed over them. When the boot inflates, it breaks the ice, and the air flowing over the airfoil blows it away.

Question 3

Where does the air come from to operate the pneumatic deicer boots on a reciprocating-engine-powered airplane?

Answer 3

From the discharge side of the air pump that is used to operate the gyro instruments.

Question 4

What is meant by a wet vacuum pump?

Answer 4

A vacuum pump that uses engine oil to lubricate its steel vanes. A dry vacuum pump uses carbon vanes, and it does not require lubrication.

Question 5

What is the purpose of the oil separator in a deicer system?

Answer 5

Oil separators are used with wet vacuum pumps to remove the lubricating oil from the discharge air before the air is used in the deicer boots.

Question 6

How are rubber deicer boots cleaned?

Answer 6

mild soap and water

Question 7

How does a thermal anti-icing system operate?

Answer 7

Hot compressor bleed air is ducted into a special chamber between a double skin in the leading edge of the wing. THis hot air is controlled by a timer so ice is allowed to build up, and then the hot air breaks its bond to the skin. Air gets under the ice and blows it away.

Question 8

What is used to remove frost from an aircraft before flight?

Answer 8

A mixture of isopropyl alcohol and ethylene glycol

Question 9

How is ice prevented from forming on the windshield of modern jet transport airplanes?

Answer 9

The windshield has a heater element embedded in it. Electric current heats the windshield and keeps ice from forming on it.

Question 10

How is ice kept from forming on the pitot tube if an airplane.

Answer 10

Pitot tubes are heated by electric current flowing through heater elements that are built into them.

Question 11

What are two ways rain can be kept from obstructing the pilot’s vision through the windshield of an airplane?

Answer 11

The rain can be blown away by a high-velocity blast of compressor bleed air, or it can be wiped away with electrically or hydraulically operated windshield wipers.

Question 12

When should rain repellent be used on an airplane windshield?

Answer 12

Only when the windshield is wet with rain.

Question 13

How is carburetor ice prevented in the engines of the smaller aircraft?

Answer 13

Heated air is directed into the carburetor. The heat comes from a muff around a part of the engine exhaust system.

Question 14

How are rubber deicer boots attached to the leading edges of aircraft wings and tail surfaces?

Answer 14

Some of them are attached with machine screws and Rivnuts; others are bonded to the surface with an adhesive.

Question 15

What keeps an electrically heated windshield from overheating

Answer 15

Heat sensors built into the windshield control the current that is used to heat the windshield.

Question 16

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

Answer 16

Hot and cold air are mixed.

Question 17

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

Answer 17

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

Question 18

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

Answer 18

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

Question 19

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

Answer 19

The air is dumped (exhausted) overboard.

Question 20

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

Answer 20

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

Question 21

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

Answer 21

Localized overheating and damage to the windshield.

Question 22

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

Answer 22

Yes, turn the pitot eater on and observe the deflection of the ammeter needle.

Question 23

Describe several potential problems associated with electrically heated windshields.

Answer 23

Arcing, delamination, scratches, and discoloration.

Question 24

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

Answer 24

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

Question 25

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

Answer 25

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

Question 26

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

Answer 26

Suction is applied to the boots.

Question 27

Why do some deicer boot systems incorporate an oil separator?

Answer 27

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

Question 28

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

Answer 28

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

Question 29

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

Answer 29

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

Question 30

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

Answer 30

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

Question 31

What power sources are used to operate windshield wipers?

Answer 31

Electricity or hydraulic pressure.

Question 32

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

Answer 32

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

Question 33

Describe the operation of a pneumatic rain removal system.

Answer 33

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

Question 34

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

Answer 34

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

Question 35

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

Answer 35

In reference material provided by the manufacturer.