Systems - Ice and Rain Protection

Question 1

Which surfaces does the pneumatic anti-icing system protect?

Answer 1

• Engine nacelles (lips)
• Wing leading edges
• Horizontal stabilizer leading edges

Question 2

Which surfaces are electrically heated to protect against ice accumulation?

Answer 2

• Pitot tubes / pitot-static tubes
• AOA sensors
• TAT probes
• Static ports
• Lav water drain
• Water service nipples

Question 3

How does the anti-ice system automatically detect ice accumulation?

Answer 3

Two ice detectors on nose of aircraft designed to accumulate ice quickly. Once ice accumulation is detected (through vibrations) a signal is transmitted to activate the pneumatic anti-ice system.

The icing signal remains valid for 60 seconds during which the ICE CONDITION advisory message is displayed on the EICAS. Simultaneously the ice detector is heated to remove the ice and return to its natural frequency.

Question 4

Can thermal anti-icing be provided by the APU?

Answer 4

No, the APU only has one stage of compression and cannot provide air which is dense/hot enough.

Question 5

Where does the anti-ice bleed air for the horizontal stabilizer come from?

Answer 5

Normally engine bleed #1. However limited anti-ice capacity can be provided by a single engine bleed up to 15,000’.

Question 6

What is the definition of icing on the ground / in the air?

Answer 6

Ground: ATIS temp less than 10°C and visible moisture is present in any form (clouds, fog with visibility of 1 mi or less, rain, snow, sleet, ice crystals).

Air: TAT less than 10°C and visible moisture is present in any form.

Question 7

How is engine lip anti-icing provided?

Answer 7

Engine anti-ice valves open automatically when the ICE DETECTION OVERRIDE knob is set to AUTO and any ice detector is activated. Valves can be manaully commanded to open by placing the knob to ALL or ENG.

Question 8

When are the horizontal stabilizer and wing anti-ice systems inhibited?

Answer 8

On the ground, with a wheel speed of less than 25 knots. (Designed to prevent structural damage caused by surface heating.

Question 9

How is a minimum compressor speed (N2) maintained during low thrust settings in icing conditions?

Answer 9

FADEC automatic logic ensures minimum available thrust during icing conditions anytime the aircraft is in flight and icing is detected. (Automatically inhibited when landing gear is extended in order to improve the rate of descent.)

Question 10

What is the desired holding configuration when in icing conditions?

Answer 10

• Gear: UP
• Flaps: UP
• Min airspeed: 200 KIAS