CRJ 200 Ice and Rain Protection Sample Questions

• How does the Ice Detector detect conditions that could lead to ice accumulation?

  The ice detectors extend into the air stream and vibrate at high frequency. When ice accumulates on the probe the frequency of the vibration is dampened and the microprocessor sends a signal to the DCU to display an EICAS caution message. The ICE DET switch light on the ANTI-ICE control panel will also illuminate.

• How will the ice detector know when the aircraft has exited ice conditions?

  When in ice conditions, the ice detector electrically heats the probe for 5 seconds during each 60-second cycle. After heating the probe, if it does not accumulate any more ice, then the indication is removed.

• What components does the Ice Detector system consist of?

  The system consists of two microprocessors and a probe on each side of the aircraft. These two systems are independent of each other. When the microprocessor detects ice on the probe, a signal is sent to the data concentrator units (DCU).

• After the ice detector detects ice and the wing and cowl anti-ice systems are turned on, how does the ice warning change?

  It changes from an amber "ICE EICAS" message to an advisory green "ICE" message.

• What happens when the 14th stage isolation valve switch light is pressed?

  The 14th stage isolation valve opens to allow both wings to be anti-iced from a single 14th stage bleed from one engine. For the valve to operate it requires bleed air and electric power. This means that the wing anti-ice must be selected on first for it to work.

• Where do the wings and cowls get bleed air for anti-icing?

  The 14th stage bleed air off the engines.

• How is bleed air directed onto the wing leading edge?

  Piccolo tubes direct hot bleed air onto the inner surface of the leading edges.

• How does the bleed air exit after heating the wing leading edge?

  The bleed air exits through louvers located under the wing leading edges.

• What happens when the WING ANTI-ICE switch is selected to NORM?

  The anti-ice temperature controller modulates the wing anti-icing valves to maintain a constant wing leading edge temperature.

• What happens when the WING ANTI-ICE switch is selected to STBY?

  This allows the temperature controller to be bypassed in case of failure. The anti-icing valves are cycled open or closed by thermal switches to maintain the leading edges at a lower temperature than the normal mode.

• What happens when there is a wing overheat condition?

  Sensors along the wing anti-icing dusk will send a signal to the DCU's and then display a WING OVHT warning on the EICAS primary page. There will also be an aural "wing overheat" warning. The A/ICE synoptic page will indicate the duct location of the overheat condition.