Flight Deck Windows Anti-Ice and Defog

CHAPTER EIGHT

STUDENT GUIDE FOR T-1A AIRCRAFT SYSTEMS

AOA Transmitter Anti-Ice System

The AOA transmitters (one located on each side of the fuselage just below the flight deck side

windows) are protected from icing by electric heat. The vane heater maintains the vane surface

temperature at approximately 260 F. A white operation light above the switch indicates current

flow.

808. FLIGHT DECK WINDOWS ANTI-ICE AND DEFOG

The flight deck windows icing and condensation protection subsystem utilizes multiple

subsystems. Electrical heating elements imbedded within layers of the windshield provide icing

prevention. The ACU subsystem supplies bleed air through the cabin air distribution ducts for

windshield condensation removal and prevention. The EHS provides supplemental window

defogging.

Windshield Heating Subsystem

The windshield construction includes a number of resistance wires placed in parallel that act as

heating elements. Each side of the divided windshield has two temperature sensors laminated

into the windshield lower forward edge. These sensors monitor heating element temperature and

provide the controller signals to open or close the heater circuit. The control unit incorporates a

warning circuit which illuminates the red windshield overheat annunciator, placarded L WSHLD

OV HT or R WSHLD OV HT on the main annunciator panel. These annunciators will also

illuminate should a malfunction occur in the system. An illuminated white operation light,

located directly above each anti-ice control switch, indicates when power is on the respective

heater elements. The operation light extinguishes when the windshield reaches the minimum

temperature and the controller cycles off, or when the switch is turned off.

809. ANTI-ICING AND DEFOG SYSTEMS LIMITATIONS

Reference Miscellaneous Limitations - Anti-Icing Limitations, Windshield Heat Limitations, and

Wing Heat Limitations, Section V, T.O. 1T-1A-1, for specific limitations of the anti-icing and

defog systems.

8-4 ANTI-ICE AND DEFOG SYSTEMS