Challenger 300/350/3500 Wing Anti-Ice (WAI) system

Effectivity: Challenger 300/350/3500 aircraft 

ATA: 30 

By Yanick Fournier – Technical Services 

The Wing Anti-Ice (WAI) system on the Challenger 300/350/3500 aircraft is designed to effectively prevent ice formation on the wings, ensuring optimal aerodynamic performance. The system is mainly used in icing conditions during takeoff, climb, descent and approach, where such conditions are more often present. 

Each wing is monitored by a Wing Anti-Ice Temperature Sensor (WAITS). The main objective of the sensor is to monitor temperature levels (Low or High) while the system is ON. The Integrated Air System Controller (IASC) will monitor the health of the sensors even when the system is OFF. The system is usually turned ON when the temperature is below 10° C (50° F) and there is moisture present in the air.   

In some cases, fuel temperature may influence the wing leading edge temperature. It is important to always follow the FCOM 1 / AFM for wing leading edge inspection prior to flight.  

In some exceptional circumstances, the WAITS may report a fault due to factors such as, but not limited to: 

• Airspeed 

• Outside air temperature 

• Angle of attack 

Usually, outside air temperature at high altitudes is stable. The U.S. Standard Atmosphere Properties set the temperature at -56.5° C (-69.7° F) between 40,000 and 50,000 feet (FL 400 and FL500). But some weather events and climate changes may affect this layer of air, resulting in lower temperatures. 

Since air has a low level of moisture at high altitude, the WAI system is not active. If the WAITS reports a fault, the system will return to normal operation once conditions return to normal. This may be due to a descent at warmer temperature, change in aircraft speed, winds, etc. 

Should the WAI system reach a high temperature during climb with the system ON, the Flight Operation Notifications Manual (FONM) FON 01-16 Ice Protection ICE-001-NC should be followed.