DOC AIRBUS | AMM A320FWINDSHIELD ANTI-ICING AND DEFOGGING - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The anti-icing and defogging system of the windshield keeps a clear visibility through the windshield and windows in icing or foggy conditions.
This objective is achieved by electrical heating of the windshield and windows.
The system is automatically started at engine start-up. A pushbutton switch also controls operation of the system (pushbutton switch in ON configuration).
The system is made up of two independent sub-systems, left and right.
Each sub-system controls heating of the windshield and windows located on the same side with respect to the aircraft centerline. Each sub-system includes:
** ON A/C NOT FOR ALL The anti-icing and defogging system of the windshield keeps a clear visibility through the windshield and windows in icing or foggy conditions.
This objective is achieved by electrical heating of the windshield and windows.
The system is automatically started at engine start-up. A pushbutton switch also controls operation of the system (pushbutton switch in ON configuration).
The system is made up of two independent sub-systems, left and right.
Each sub-system controls heating of the windshield and windows located on the same side with respect to the aircraft centerline. Each sub-system includes:
- one windshield,
- two windows:
. one sliding and one fixed (aft), - one Window Heat Computer (WHC).
In each sub-system, the windshield temperature regulation and the window temperature regulation are independent.
2. Component Location
** ON A/C NOT FOR ALL 
Windshield Anti-icing and Defogging - Control Location| FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C ALL | |||||
| 2DG1 | WHC-1 | 121 | 30-42-34 | ||
| 3DG1 | WINDSHIELD-L | 211 | 56-11-11 | ||
| 7DG1 | WINDOW-FIXED, L | 211 | 56-11-12 | ||
| 8DG1 | WINDOW-SLIDING, L | 211 | 56-12-11 | ||
| 2DG2 | WHC-2 | 122 | 30-42-34 | ||
| 3DG2 | WINDSHIELD-R | 212 | 56-11-11 | ||
| 7DG2 | WINDOW-FIXED, R | 212 | 56-11-12 | ||
| 8DG2 | WINDOW-SLIDING, R | 212 | 56-12-11 | ||
3. System Description
Two temperature sensors (or optionally three depending on the windshield part number), are installed inside each windshield (one sensor active, the other(s) spare).
Two temperature sensors (one is in spare, which can be used permanently if the first one fails) are installed in each of the fixed and sliding side windows.
The regulation threshold of the WHC is between 35 and 42 deg.C (95 and 107.6 deg.F). The temperature is monitored by the in-service sensor.
Two heating power levels are available for the windshield:
One heating power level only is available for the windows: 15 W/dm2 on the ground as well as in flight.
A 115 VAC/400 Hz line delivers this power output.
Detection of window extreme temperatures or failure of associated temperature sensor causes:
** ON A/C NOT FOR ALL Two temperature sensors (or optionally three depending on the windshield part number), are installed inside each windshield (one sensor active, the other(s) spare).
Two temperature sensors (one is in spare, which can be used permanently if the first one fails) are installed in each of the fixed and sliding side windows.
The regulation threshold of the WHC is between 35 and 42 deg.C (95 and 107.6 deg.F). The temperature is monitored by the in-service sensor.
Two heating power levels are available for the windshield:
- 23 W/dm2 on the ground,
- 70 W/dm2 in flight only (not allowed on the ground).
One heating power level only is available for the windows: 15 W/dm2 on the ground as well as in flight.
A 115 VAC/400 Hz line delivers this power output.
Detection of window extreme temperatures or failure of associated temperature sensor causes:
- activation of a warning in the cockpit,
- automatic cut off of the heating of the defective window.
- +60 deg.C (140 deg.F): corresponds to an overheat or to the sensor in open circuit,
- -60 deg.C (-76 deg.F): corresponds to the sensor in short circuit.
NOTE: A lighted icing indicator is installed on the outer face of the windshield post to indicate the presence of ice.
4. Power Supply
The supply and protection of the components and functions is given below:
** ON A/C NOT FOR ALL The supply and protection of the components and functions is given below:
| ------------------------------------------------------------------------------- |
| !COMPONENT/FUNCTION ! CIRCUIT BREAKER ! BUSBAR ! |
| !------------------------------------------!---------------------!------------! |
| ! Heating of L windshield ! 1DG1 ! 1XP ! |
| ! Heating of R windshield ! 1DG2 ! 2XP ! |
| ! Heating of L windows (fixed and sliding) ! 4DG1 ! 101XP-B ! |
| ! Heating of R windows (fixed and sliding) ! 4DG2 ! 202XP-C ! |
| ! Supply of WHC1 ! 5DG1 ! 101PP ! |
| ! Supply of WHC2 ! 5DG2 ! 202PP ! |
| ------------------------------------------------------------------------------- |
5. Interface
The windshield anti-icing and defogging system is related to the systems given below:
** ON A/C NOT FOR ALL The windshield anti-icing and defogging system is related to the systems given below:
- the Engine Interface Unit (EIU) (Functional Interfaces) to ensure the heating control,
- the landing gear shock-absorbers to ensure the selection of the heating mode (for the windshield),
- the Centralized Fault Display Interface Unit (CFDIU),
- the System Data Acquisition Concentrator (SDAC).
6. Component Description
A. Windshield FIN: 3-DG-1 FIN: 3-DG-2
The heating element is a film.
Two temperature sensors (or optionally three depending on the windshield partnumber), are installed inside each windshield (one sensor active, the other(s) spare).
The heating element is a film.
Two temperature sensors (or optionally three depending on the windshield partnumber), are installed inside each windshield (one sensor active, the other(s) spare).
B. Fixed and Sliding Windows FIN: 7-DG-1 FIN: 7-DG-2 FIN: 8-DG-1 FIN: 8-DG-2
The heating element of the window is a film.
Two single loop sensors are installed in each of the sliding and fixed windows. The loops are of the compact type.
The heating element of the window is a film.
Two single loop sensors are installed in each of the sliding and fixed windows. The loops are of the compact type.
C. WHC FIN: 2-DG-1 FIN: 2-DG-2
The WHC does the functions that follow:
The minimum range of the temperature which includes the tolerances is between 30 DEG.C (86 DEG.F) and 38 DEG.C (100 DEG.F).
The temperature sensor cuts off the heat when the temperature is -60 DEG.C (-76 DEG.F) or 60 DEG.C (140 DEG.F).
The WHC supplies two levels of heat for the windshield as follows:
The WHC does the functions that follow:
- Controls the temperature
- Monitors the system
- Safety the equipment.
- One for the right side that is identified as WHC2
- One for the left side that is identified as WHC1.
The minimum range of the temperature which includes the tolerances is between 30 DEG.C (86 DEG.F) and 38 DEG.C (100 DEG.F).
The temperature sensor cuts off the heat when the temperature is -60 DEG.C (-76 DEG.F) or 60 DEG.C (140 DEG.F).
The WHC supplies two levels of heat for the windshield as follows:
- A high level of heat during the flight with the inputs from [5GA1] and [5GA2]
- A low level of heat on the ground with the inputs from [5GA1] and [5GA2] .
7. Operation/Control and Indicating
A. Monitoring
The faults of the heating system of each window are shown on the ECAM display unit. The WHC automatically stops heating.
The WHC serves to:
Two discrete outputs (one for the windshield, one for the two windows) inform the crew of a heating fault.
The WHC transmits this information to the Flight Warning Computer (FWC).
The faults of the heating system of each window are shown on the ECAM display unit. The WHC automatically stops heating.
The WHC serves to:
- identify the faulty component(s),
- store the fault(s) in a memory which is not erased after supply cut-off.
Two discrete outputs (one for the windshield, one for the two windows) inform the crew of a heating fault.
The WHC transmits this information to the Flight Warning Computer (FWC).
B. Maintenance Test
A signal from the CFDIU permits to check the correct operation of the system and of the related safety features.
The ground/flight transition deletes the memory.
A signal from the CFDIU permits to check the correct operation of the system and of the related safety features.
The ground/flight transition deletes the memory.
C. Leading Particulars
(1) A loss of 28 Volt supply is indicated as a failure.
(2) The WHC includes electromagnetic power contactors.
(3) The WHC also incorporates protections against overvoltages due to lightning strike and to static electricity on the windows.
(4) The power outputs are protected against short circuits.
(5) The test function is inhibited in flight.
8. BITE Test
The WHC performs a maintenance test initiated by the CFDIU and a power-up test.
The purpose of the test is to check the following:
The WHC performs a maintenance test initiated by the CFDIU and a power-up test.
The purpose of the test is to check the following:
- Internal circuits: - CPU (RAM, EPROM, microprocessor itself)
- acquisition of discrete inputs - analog acquisition circuits - discrete and power outputs. - External circuits: - continuity of window and windshield heating elements
- integrity of sensors - continuity of the DSO lines (only in CFDIU test).
A. Power-up Test Initialization and Cockpit Repercussions
(1) Conditions of power-up test initialization
- de-energization time of computer: 5 s.
- A/C configuration:
- whatever the A/C configuration on ground.
(2) Progress of power-up tests
- Duration: 5 s.
- Cockpit repercussions (ECAM warning, audio warning, pushbutton switch flashing, if any):
- none
(3) Results of power-up tests
(cockpit repercussions, if any, in case of tests passed/tests failed)
(cockpit repercussions, if any, in case of tests passed/tests failed)
(a) Tests passed:
- none.
(b) Tests failed:
- ECAM warning:
- ANTI-ICE L (R) WINDSHIELD
- ANTI-ICE L (R) WINDOW
NOTE: The WHC 1 controls the left systems.
The WHC 2 controls the right systems.
The WHC 2 controls the right systems.