Ice and Rain Protection

Question 1

Describe the engine anti ice.

Answer 1

Engine anti ice is electrically controlled and pneumatically activated. The valve is automatically closed if no air is supplied.

If the aircraft enters the emergency electrical configuration, the engine anti-ice valves automatically open to ensure engine anti-ice is available.

Engine bleed air does not need to be selected to use engine anti-ice.

Question 2

Which slats does wing anti-ice provide hot bleed air to?

Answer 2

Wing anti-ice provides hot bleed air from the pneumatic system to heat the outboard 3 wing slats (3, 4 and 5).

Wing anti-ice capability is reduced with the slats extended; therefore prolonged flight in icing conditions in this configuration should be avoided.

Question 3

Wing anti-ice valves automatically close when:

Answer 3

• Bleed air pressure is lost on the corresponding side
• A bleed leak is detected on the corresponding side
• A total loss of AC power

Question 4

When would there be a FAULT light for WING ANTI ICE?

Answer 4

WING ANTI ICE FAULT light will remain illuminated if the position of the valve disagrees with the commanded position or a low pressure is detected, and will momentarily be illuminated while the valves are in transit.

Question 5

When ENGINE ANTI ICE is selected:

Answer 5

• The engine’s EPR limit is reduced
• The engine’s idle speed increases
• A green ENG A. ICE memo appears on the E/WD

Question 6

When WING ANTI ICE is selected:

Answer 6

• The engine’s thrust limit on both engines is automatically reduced.
• The WING A.ICE memo appears on the E/WD
• The ANTI-ICE indications appear on the BLEED page

Question 7

What occurs if the WING ANTI ICE pb is selected ON on the ground?

Answer 7

If the WING ANTI ICE pb is selected ON while on the ground, the wing anti-ice valves open for a brief test sequence. After a short time, the valves automatically close and the ANTI ICE indication disappears. The valves will reopen at liftoff resulting in a negative impact on takeoff performance.

Question 8

How does the automatic ice detection system work?

Answer 8

Some aircraft are equipped with an automatic ice detection system which consists of two ice detection probes installed on the lower section of the forward fuselage. The system is active whenever the aircraft is above 1500’ AGL and the TAT is less than 10°C. The probes vibrate and change frequency depending on the amount of accumulated ice. ICE NOT DET memo displays if anti-icing is on and icing conditions have not been detected for approximately 3 minutes.

The ice detection system does not automatically activate any anti-icing.

Question 9

When does automatic windshield and window heating occur?

Answer 9

The windshields and windows are heated when at least one engine is running on the ground and whenever the aircraft is in flight.

Windshield heating operates at low power on the ground and at normal power in flight. The changeover is automatic. Only one heating level exists for the windows.

Question 10

What is the purpose of the PHCs?

Answer 10

Three independent probe heat computers (PHCs) automatically control and monitor electrical heating to:
* Pitot tubes
* Static ports
* Total Air Temperature probes
* AoA probes

TAT probes are not heated on the ground to avoid inaccurate readings during ground operations. Pitot tube heating operates at a low level on the ground and automatically shifts to a normal power level when in flight. The waste water drain masts are automatically heated whenever AC power is online.