ATA 30

Cooling the Windshield Temp Sensor
Summertime is here and in full force, especially down here in Texas. But we still have to perform anti-ice system inspections such as of the “Inspection of Windshield Heat Cycling Contactor (WCC) I.A.W. 30-40-00 para. 1.B.”, which is accomplished at every “A” Inspection. In order to perform the check, you will have to cool the temp sensor within the windshield if the outside air temperature is 100°F or greater. The Maintenance Manual calls out to pour water over the temp sensor to lower the temperature. I use a plastic bag with ice in it and simply stick it under the windshield wiper blade over the temp sensor (this is considerably less messy). By all means, DO NOT spray the glass windshield with any type of freeze spray. There is a caution in the Maintenance Manual in the following paragraph (1.C.) “DO NOT SUBJECT WINDSHIELD TO THERMAL SHOCK OF SUDDEN TEMPERATURE CHANGES…MAY RESULT IN A FAILURE OF WINDSHIELD GLASS THROUGH THERMAL STRESS.” I have seen the “freeze spray” results on another type of aircraft, and I can attest to you that it wasn’t pretty. You also must consider the possibility that the outer windshield on the Westwind might not have been shimmed properly at the last install, resulting in it being slightly stressed already. It may not take much more to break it.