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Ice Detection System
There are 2 ice detectors mounted on the nose of the aircraft as close to the free air stream as possible. They are used to automatically activate engine and wing anti-ice systems with the mode selector in AUTO. The ice detectors have a mechanical element which vibrates at a given frequency. Accumulation of ice causes a change in the frequency. When a pre-determined change is detected, the ice detector sends a signal to the AMS controller (through the MAU and SPDA 2). An inbuilt heating element then sheds the ice so that the detector can continue to operate.
At low speeds during ground operation the ice detectors may not detect an icing condition. If icing is detected, the ice detectors command the wing and engine anti-ice valves to remain open and activated for 5 minutes after the icing condition is no longer detected.
Control panel
| ON | engine anti-ice systems activate whenever the engines are running |
EICAS messages
ICE CONDITION - left or right detector senses ice; inhibited below 1,700' afe and for 2 minutes after takeoff
STALL PROT ICE SPEED - comes on with ICE CONDITION and remains on for entire flight