Anti-Ice, Rain -System Description 737 Operations Manual
Flight Deck Window Heat
Flight deck windows 1, 2, 4 and 5 consist of glass panes laminated to each side of a vinyl core. Flight deck window 4 has an additional vinyl layer and acrylic sheet laminated to the inside surface. On airplanes with flight deck window 3 not heated, the window consists of two acrylic panes separated by an air space. On airplanes with flight deck window 3 heated, the window consists of glass panes laminated to each side of a vinyl core.
A conductive coating on the outer glass pane of windows 1 and 2 permits electrical heating to prevent ice build–up and fogging. A conductive coating on the inner glass pane of windows 3, 4 and 5 permits electrical heating to prevent fogging. On some airplanes, window 3 is not electrically heated.
Flight Deck Window Heat Operation
The FWD WINDOW HEAT switches control heat to window 1. The SIDE WINDOW HEAT switches control heat to windows 2, 3, 4 and 5. On some airplanes, window 3 is not electrically heated.
Temperature controllers maintain windows 1 and 2 at the correct temperature to ensure maximum strength of the windows in the event of bird impact. Power to windows 1 and 2 is automatically removed if an overheat condition is detected. Thermal switches – located on windows 3 and 5 – open and close to maintain the correct temperature of windows 3, 4 and 5. On airplanes without window 3 electrical heat, window 3 does not have a thermal switch.
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3.20.2 December 1, 2000
Anti-Ice, Rain -System Description
Flight Deck Window Heat Schematic
As installed
Copyright . The Boeing Company. See title page for details.
December 1, 2000 3.20.3
Anti-Ice, Rain -System Description 737 Operations Manual
Windshield Wipers and Rain Repellent
The rain removal system for the forward windows consists of windshield wipers and rain repellent (rain repellent is inoperative on some airplanes). One windshield wiper is located on each No. 1 window. Each wiper is electrically operated by a separate system. Both wiper systems are controlled by a common switch. Each push of a rain repellent switch applies a measured amount of repellent on the related No. 1 windshield.
CAUTION: Windshield scratching will occur if the windshield wipers are operated on a dry windshield.
Probe and Sensor Heat
All pitot-static probes, the total air temperature probe, and angle airflow sensors are electrically heated to prevent the formation of ice. Alternate static ports are not heated.
Engine Anti–Ice System
Engine bleed air thermal anti–icing prevents the formation of ice on the engine cowl lip. Engine anti–ice operation is controlled by individual ENG ANTI–ICE switches. The engine anti–ice system may be operated on the ground and in flight.
Engine Anti–Ice System Operation
Each cowl anti–ice valve is electrically controlled and pressure actuated. Positioning the ENG ANTI–ICE switches to ON allows engine bleed air to flow through the cowl anti–ice valve for cowl lip anti–icing.
If the cowl anti–ice valve fails to move to the position indicated by the ENG ANTI–ICE switch, the COWL VALVE OPEN light remains illuminated bright blue.
The amber COWL ANTI–ICE light illuminates due to excessive temperature or pressure in the duct leading from the cowl anti–ice valve to the cowl lip.
Copyright . The Boeing Company. See title page for details.
3.20.4 December 1, 2000
Anti-Ice, Rain -System Description
Engine Anti–Ice System Schematic
Wing Anti–Ice System
The wing anti–ice system provides protection for the leading edge slats by using
bleed air. The wing anti–ice system does not include the leading edge flaps. The wing anti–ice control valves are AC motor–operated. With a valve open, bleed air flows to the leading edge slats through a telescoping duct, and is then exhausted overboard. The wing anti–ice system is effective with the slats in any position.
Wing Anti–Ice System Operation Airplanes with Ground Wing Anti-ice
On the ground, positioning the WING ANTI–ICE switch ON opens both control valves if thrust on both engines is below the setting for takeoff warning activation and the temperature inside both wing distribution ducts is less than the thermal switch activation temperature.
Anti-Ice, Rain -System Description
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