11.12 Ice And Rain Protection

Question 1

What 2 systems are there for rain protection?

Answer 1

• Windshield Wiper

- Rain repellent system

Question 2

what negative effects does ice have on an aircraft? [3]

Answer 2

• increase in drag
• decrease in lift
• weight increase

Question 3

what range of temperature can water droplets form clear ice on the surface of the aircraft?

Answer 3

0 degrees to -10 degrees

Question 4

what ice is formed when the temperature drops below -10 degrees?

Answer 4

Rime-ice

Question 5

whats is a thermal wing anti ice system?

Answer 5

where on the leading egde, heat is used to melt any ice formed

Question 6

what 2 negative effects can ice have on engine inlets?

Answer 6

• disturbs air flow = a reduction in engine performance and compressor stall
• damage to fan blades and inlet vanes

Question 7

what do engine inlets have to prevent ice build up?

Answer 7

thermal anti ice system

Question 8

what is aerofoil de-icing?

Answer 8

using rubber boots on leading edges of wings and stabilisers rather than warm air from pnuematics

Question 9

how do the rubber boots work? (aerofoil de-icing)

Answer 9

They inflate for a short time by pressurised air, cracking the ice which is blown away by the airflow

Question 10

what type of ice detection is a probe on the front of the aircraft that collects ice where its visible to the pilots?

Answer 10

Optical Ice detector

Question 11

what types of ice detection systems are there? [3]

Answer 11

• Optical ice detector
• rotary ice detector
• electronic ice detector

Question 12

how do electronic ice detectors work?

Answer 12

Tips of the detector vibrate with a frequency that reduces with ice formation

Question 13

where are thermal anti-ice systems are installed on the aircraft? [2]

Answer 13

• the wing

- engine

Question 14

what is the name of the vales that connect the wing anti ice ducts to the pnuematics?

Answer 14

wing anti ice valve

Question 15

where does the warm air come from to anti ice the engine?

Answer 15

directly from the engine

Question 16

what valve connects the engine to the pneumatics to provide anti ice?

Answer 16

engine anti ice valve

Question 17

what is found in the wing or engine anti ice ducts to spray them with hot air?

Answer 17

small holes

Question 18

what duct is equipped to the leading edge when slats are installed for anti ice?

Answer 18

telescopic duct

Question 19

what main valves is used to regulate the air coming from the pnuematics to the anti systems?

Answer 19

bleed valve

Question 20

how many switches do the wing anti ice systems have? and why?

Answer 20

• 1

- they must always operate symmetrically as one may have a reduction in lift if not switched on.

Question 21

how many switches are there for the engine anti ice system?

Answer 21

1 for each engine

Question 22

when are anti ice systems normally operative?

Answer 22

during flight

Question 23

when can you switch on the anti ice systems on the ground?

Answer 23

to check operation of the valves before flight

Question 24

when are engine anti ice systems always available?

Answer 24

when there is bleed air from the engine

Question 25

what types of valves can be found in the anti-ice system? [2]

Answer 25

• electrical motor operated valves

- solenoid controlled pressure operated valves

Question 26

when would the solenoid controlled valve close by a spring?

Answer 26

when there is no pressure

Question 27

how does a solenoid controlled valve operate? [2]

Answer 27

• de-energised solenoid = pressure from airflow fills the lower chamber of the valve cylinder, pushing the piston up, moving air in the top part of the cylinder to ambient. opens valve
• energised solenoid = brings high pressure to the upper part of the cylinder to equalise the pressure on both sides, but closes under spring pressure

Question 28

what does the engine anti ice solenoid controlled valve do under a fail safe operation?

Answer 28

automatically open with no electrical power

Question 29

what monitors valve position?

Answer 29

limit switches

Question 30

when will a fault light illumincate on wing anti ice pushbutton?

Answer 30

when the pressure doesnt reach 14 psi

Question 31

when does the aircraft only use 50% of AC power?

Answer 31

when on the ground