Ice Protection/Detection

Question 1

What sources are used for aircraft anti-icing and de-icing?

Answer 1

Bleed air heat (De-Icing) Engine Cowls, Wings (3 outer Slats)

Electric Heat (Anti-Icing)
Windshields, Smart Data Probes, TAT probes, water lines, Pressurization static port

Question 2

What uses bleed air for ice protection?

Answer 2

Engine Cowl, 3 outboard wing slats (slats 2, 3 and 4 on each wing)

Question 3

What uses electric heat for ice protection?

Answer 3

Smart probes
TAT probes
Windshields
Water lines
Pressurization static port

Question 4

If an engine fails does the opposite wing and engine receive ice protection?

Answer 4

Yes, the crossbleed valve opens to provide symmetrical ice protection for both wings.

However, the failed engine does not receive heat to engine cowl.

Question 5

How many ice detectors must be working to have icing detection?

Answer 5

One. There are two for redundancy.

Dual detector failure means crew must use manual mode.

Question 6

How long will the de-icing system remain on after icing is no longer detected?

Answer 6

5 minutes
(Ice Speeds Advisory message stays on for remainder of flight)

Question 7

If REF A/I on the MCDU is set to ‘OFF’ and on takeoff roll icing conditions are encountered, will the de-icing system turn on?

Answer 7

Not until 1700 ft. or 2 minutes after takeoff
(whichever occurs first)
The MCDU “REF AI OFF” inhibits the Ice detector logic until 1,700 ft.

Question 8

Can the APU be used to provide bleed air for anti-icing?

Answer 8

No
The APU is not capable of supplying bleed air for the anti-ice operations

Question 9

What is protected from ice and rain?

Answer 9

Engine inlets
Wing leading edge (slats 2,3 and 4)
Smart probes and TAT probes
Windshields
Water and waste drain systems
Static Pressure Port

Question 10

Is the ice protection system automatic?

Answer 10

Yes, under normal conditions

On ground, do not rely on visual icing evidence or Ice Detector actuation to turn on Anti-Ice. Use temperature and visible moisture criteria.

Question 11

Can the pilot override the automatic system?

Answer 11

Yes, by moving the Ice Protection mode switch to ‘ON’.

Question 12

How is ice detected in flight?

Answer 12

2 ice detectors
Vibrating sensor element that changes frequently when ice builds up around it.

Once ice is detected, the sensor element heats, the ice melts, the normal vibrating characteristics are restored, and the heating process stops. The cycle repeats as ice rebuilds on the probes

Question 13

What compressor stage is bleed air tapped for anti-icing operations?

Answer 13

10th High Stage Valve (HSV)
(engine cowls and or slats)

6th stage (slats only)

Question 14

How is bleed air directed for pneumatic anti-ice?

Answer 14

Engines (onside only)

Wings (onside priority, offside if bleed source failure)

Question 15

What happens if there is a single bleed source failure?

Answer 15

The crossbleed valve automatically opens and uses the opposite bleed for both wings (slats 2,3 and 4)

Question 16

How should the MCDU be set if there are icing conditions present on the ground?

Answer 16

TO Data set to ‘ALL’ when visible moisture and below 5c.

‘ENG’ when visible moisture and temperature is 10c or below to 6c.

Question 17

What does selecting ‘ALL’ on the MCDU provide?

Answer 17

Engine anti-ice: ON when engines are running.

Wing anti-ice: ON at 40 kts wheel speed

Question 18

If ‘All’ is selected on the ground, at what point will the anti-ice system become automatic?

Answer 18

Engine Cowls come on at engine start.

Wings come on at 40kts wheel speed

Question 19

If ‘OFF’ is selected on the ground, at that point will the anti-ice system become automatic

Answer 19

1700’ AGL or 2 minutes after takeoff (whichever happens first)

Question 20

How does the failure of one of the two power sources affect the windshield heating system?

Answer 20

On the ground: inhibited.
In flight: Left side is heated (right heats if left has failed).

Question 21

What does ‘TIMER’ selection on the windshield wiper switch do?

Answer 21

Activates the associated wiper in 8-second intervals.

Question 22

What happens if the wiper is operated on a dry windshield?

Answer 22

The wiper will stop.
To reset wiper move switch to ‘OFF’

Question 23

When do the smart probes heat?

Answer 23

• When an engine is running
• In flight; or
• When the ADS probe heater button is pushed with the AC power without engines running on the ground.

Question 24

Is there a test for the anti-ice system?

Answer 24

Yes, but maintenance performs this test.

Question 25

How should the aircraft be configured for de-icing?

Answer 25

Bleeds: OFF
Packs: OFF
Stab trim: Full nose down
Flaps: UP
Engines and APU: ON or OFF
Note: APU is recommended OFF.
Use the De-icing/Anti-icing Fluid application checklist.