Anti-Ice and Rain - Probe Heat

Operation of the probe heat system is fully automatic. Power to the electrically heated probes is applied any time an engine is running and all probe heat lights extinguish. However, only the pitot and AOA probes are heated; power to the TAT probe is inhibited on the ground by the Air/Ground Logic System.

Probe Heat Lights and Messages

An individual probe heat light illuminates and the associated EICAS advisory message displays when a probe is not being heated. If two or more probe lights illuminate, the EICAS advisory message PROBE HEAT displays.

Probe Heat Test

The probe heat test checks the operational status of the probe heat system. To accomplish this test, the airplane must be on the ground and the engines shut down. The probe heat lights illuminate and an EICAS advisory message PROBE HEAT displayed. Pushing the Window/Probe Heat Test Switch applies power to all probes, extinguishes the Probe Heat Lights and EICAS message. If a fault is detected, the faulty probe light remains on and the associated EICAS message appears. When the test switch is released the probe heat lights and message re-appear.

Ice Detection