DOC AIRBUS | AMM A320FWINDSHIELD RAIN PROTECTION - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
Rain removal from the right and left windshields is achieved by two systems:
Rain removal from the right and left windshields is achieved by two systems:
- a wiper system,
- a rain repellent fluid system.
A. Wiper System
Wiper System - Controls Location- Two wipers are available, one for the left (Captain) windshield and one for the right (First Officer) windshield.
- The two wipers are independently actuated through two-speed electric motors controlled by the WIPER control switches.
- The wipers have a parking position clear of the area of visibility with the wiper blades just lifted from the windshield surface to avoid sand accumulation which could cause scratching of the windshield.
B. Rain Repellent System
(1) The system is designed to improve visibility through the windshield in heavy rain particularly when the wipers are not sufficient.
(2) The system enables a special rain-repellent fluid to be sprayed in one or several applications on the windshield; the fluid is designed to increase the surface tension of water.
The increase in surface tension:
The increase in surface tension:
- eliminates the film of water on the windshield; the water film is of variable thickness and impairs vision,
- causes water to remain in the form of droplets (similarity with mercury),
- facilitates evacuation of these droplets under dynamic effect of airstream; the droplets do not wet the windshield surface. Purging of the spray nozzles with air serves to prevent clogging.
2. Component Location
** ON A/C NOT FOR ALL | FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C ALL | |||||
| 3DB1 | SOL VALVE-RAIN RPLNT, CAPT | 211 | 30-45-41 | ||
| 3DB2 | SOL VALVE-RAIN RPLNT, F/O | 212 | 30-45-41 | ||
| 5DB1 | CTL SW-WIPER, CAPT | 21VU | 211 | 30-45-11 | |
| 5DB2 | CTL SW-WIPER, F/O | 22VU | 212 | 30-45-11 | |
| 6DB1 | MOTOR CONVERTER-WIPER, CAPT | 211 | 30-45-51 | ||
| 6DB2 | MOTOR CONVERTER-WIPER, F/O | 212 | 30-45-51 | ||
| 304DM | BLADE-WIPER, F/O | 212 | 30-10-00 | ||
| 305DM | BLADE-WIPER, CAPT | 211 | 30-10-00 | ||
| 306DM | ARM-WIPER, F/O | 212 | 30-10-00 | ||
| 307DM | ARM-WIPER, CAPT | 211 | 30-10-00 | ||
| ** ON A/C NOT FOR ALL | |||||
| 1DM | CAN ASSY-RAIN RPLNT FLUID | 211 | 30-10-00 | ||
| ** ON A/C ALL | |||||
| 2DM | GAGE ASSY-RAIN RPLNT FLUID | 211 | 30-10-00 | ||
| 3DM | CHECK VALVE-RAIN RPLNT | 120 | 30-45-46 | ||
| 4DM | CHECK VALVE-RAIN RPLNT | 120 | 30-45-46 | ||
3. System Description
A. Wipers
Two totally independent sub-systems are provided:
Each sub-system ensures that clear vision is maintained through the windshield during all rain conditions and during the following flight phases:
Two totally independent sub-systems are provided:
- CAPT sub-system (left windshield),
- F/O sub-system (right windshield).
Each sub-system ensures that clear vision is maintained through the windshield during all rain conditions and during the following flight phases:
- taxi,
- takeoff,
- approach,
- landing.
- slow operation (SLOW position),
- fast operation (FAST position),
- stop (OFF position) in a parking position of the arm/blade assembly.
| ------------------------------------------------------------------------------- |
| ITEM DESIGNATION QTY COMMENTS |
| ------------------------------------------------------------------------------- |
| 1 Motor converter 1 Motors identical, |
| converters |
| symmetrical |
| 2 Arm (rigid) 1 Identical for |
| CAPT and F/O |
| 3 Blade 1 Identical for |
| CAPT and F/O |
| 4 Control switch 1 Identical for |
| CAPT and F/O |
B. Rain Repellent
(1) The rain repellent fluid used is packaged in a nitrogen pressurized can.
The nitrogen pressurizes the lines of the rain repellent system.
The nitrogen pressurizes the lines of the rain repellent system.
(2) The can is directly fitted to the rain-repellent fluid gage, thus enabling the sealing valve of the can to open.
(3) The components given below are located on the side of the rain-repellent fluid gage:
- a pressure gage indicating the pressure in the system and thereby the remaining fluid,
- a purge pushbutton used to purge the lines when the can is replaced.
(4) Lines release the fluid to each of the two spray systems which operate independently.
(5) A fluid spray system is provided for each windshield.
It incorporates the components given below:
It incorporates the components given below:
- a solenoid valve (time controlled),
- a control pushbutton switch,
- a spray nozzle.
(6) A CAPT(FO) RAIN RPLNT pushbutton switch, located in the cockpit, serves to control the system.
Upon actuation of the pushbutton switch, the time-controlled solenoid valve of the associated system enables fluid release to the spray nozzles for a limited period.
To initiate a new cycle, it is necessary to release then to push again the control pushbutton switch.
Upon actuation of the pushbutton switch, the time-controlled solenoid valve of the associated system enables fluid release to the spray nozzles for a limited period.
To initiate a new cycle, it is necessary to release then to push again the control pushbutton switch.
(7) Each solenoid valve is installed as near as possible to its associated spray nozzle to limit:
- the response time of the system,
- loss of fluid between the valve and the nozzle,
- the risks of internal clogging due to the evaporation of the residual fluid.
(8) Each spray nozzle protrudes from the skin panel of the aircraft and incorporates four directional orifices with calibrated diameters.
The two nozzles are arranged symmetrically and are not interchangeable ; precise angular positioning is required.
The two nozzles are arranged symmetrically and are not interchangeable ; precise angular positioning is required.
(9) The purge system is provided to eliminate the fluid remaining between the check valve and the nozzle after each application of the fluid. The hot air manifold of the air conditioning system supplies the purge air at a pressure of 4 plus or minus 1 PSID with reference to the cabin pressure.
The assembly comprising the check valves and the rain-repellent blowout reservoir:
The assembly comprising the check valves and the rain-repellent blowout reservoir:
- enables air to flow permanently to the spray nozzles when the rain-repellent system does not operate,
- shuts off the air supply lines during spraying of the rain-repellent fluid.
(10) The system is inhibited on the ground (connection to the Engine Interface Unit (EIU)).
4. Power Supply
Power supply to and protection of the equipment and the function are provided as follows:
The supply and protection of the solenoid valves is as follows:
** ON A/C NOT FOR ALL Power supply to and protection of the equipment and the function are provided as follows:
| ------------------------------------------------------------------------------ |
| !EQUIPMENT - FUNCTION CIRCUIT BREAKERS BUSBARS ! |
| !----------------------------------------------------------------------------! |
| !CAPT Wiper Motor Converter 4DB1 101PP ! |
| !----------------------------------------------------------------------------! |
| !F/O Wiper Motor Converter 4DB2 202PP ! |
| ------------------------------------------------------------------------------ |
The supply and protection of the solenoid valves is as follows:
| ------------------------------------------------------------------------------ |
| !COMPONENT - FUNCTION CIRCUIT BREAKERS BUSBARS ! |
| !----------------------------------------------------------------------------! |
| !CAPT rain-repellent solenoid 1DB1 101PP ! |
| !valve ! |
| !----------------------------------------------------------------------------! |
| !F/O rain-repellent solenoid 1DB2 202PP ! |
| !valve ! |
| ------------------------------------------------------------------------------ |
5. Interfaces
The rain-repellent system is connected to the Engine Interface Unit (EIU) system; this ensures inhibition of the rain-repellent system on the ground, with engines shut down.
** ON A/C NOT FOR ALL The rain-repellent system is connected to the Engine Interface Unit (EIU) system; this ensures inhibition of the rain-repellent system on the ground, with engines shut down.
6. Component Description
A. Wiper System FIN: 6-DB-1 FIN: 6-DB-2
(a) The motor and converter form a single assembly.
(b) The motor is provided with a thermal protection which protects the mechanical and electrical components of the system.
(c) The motor converter assembly provides the sweeping angles defined on the referenced figure, via the wiper arm/blade assembly
The motor converter serves to obtain the parking position of the wiper arm when the WIPER control switch is placed in the OFF position.
The converter changes the rotary motion of the motor into an oscillatory motion of the wiper arm (alternate sweeping).
The motor leading particulars are:
The motor converter serves to obtain the parking position of the wiper arm when the WIPER control switch is placed in the OFF position.
The converter changes the rotary motion of the motor into an oscillatory motion of the wiper arm (alternate sweeping).
The motor leading particulars are:
- direct current,
- permanent magnet,
- two rotation speeds (slow/fast) for sweeping,
- one slow speed, inverted rotation, for the parking position.
(2) CAPT and F/O wiper arms
Each rigid arm serves to adjust the parking position angle (lower position) to plus or minus 1 deg. by the use of a splined bushing between the converter output shaft and the arm.
The arm/blade junction is rigid enough to maintain the blade/arm angle constant in all the utilization cases.
The pressure of the arm on the windshield is adjustable,
A roller device allows the adjustment of the arms on the rest blocks.
The arm is coated with a dull-black anti-reflective paint.
Each rigid arm serves to adjust the parking position angle (lower position) to plus or minus 1 deg. by the use of a splined bushing between the converter output shaft and the arm.
The arm/blade junction is rigid enough to maintain the blade/arm angle constant in all the utilization cases.
The pressure of the arm on the windshield is adjustable,
A roller device allows the adjustment of the arms on the rest blocks.
The arm is coated with a dull-black anti-reflective paint.
(3) Blade
- The form of the blade is designed to ensure even sweeping of the windshield in all the utilization conditions; the tolerances of the blade pressure adjustment must be observed, (Ref. Para (6)(a)).
- It is possible to replace the blade without removing the arm.
- When the wiper system is in operation, the blade should in no case overlap onto the metal frame of the windshield.
(4) Control switch
The WIPER control switch located on the overhead panel (panels 21VU and 22VU) incorporates a quick-break device which enables electrical switching in the following positions:
The WIPER control switch located on the overhead panel (panels 21VU and 22VU) incorporates a quick-break device which enables electrical switching in the following positions:
- OFF: parking and stop position,
- SLOW: slow speed,
- FAST: fast speed.
(5) Parking position and liftoff device
When the wiper system is selected OFF, the arm/blade assembly stops in the parking position; in this position, the arm is lifted off with respect to the aircraft structure, at the windshield lower part (parking position).
The liftoff device avoids any risk of collecting dust, sand or other abrasive particles which could cause windshield damage upon next operation of the wipers.
When the wiper system is selected OFF, the arm/blade assembly stops in the parking position; in this position, the arm is lifted off with respect to the aircraft structure, at the windshield lower part (parking position).
The liftoff device avoids any risk of collecting dust, sand or other abrasive particles which could cause windshield damage upon next operation of the wipers.
(6) Various characteristics
(a) Sweeping pressure
The pressure of the wiper arm-blade assembly is adjustable within the range of pressures corresponding to forces between 2 daN (4.4962 lbf) and 5.5 daN (12.3645 lbf); these are applied to the center of the blade perpendicular to the windshield plane.
Within these limits, there is no degradation of the system performance.
In all the utilization conditions (normal or abnormal operation of the wiper system), rupture of one or several parts of this system will not result in damage to the aircraft structure or the engines.
If, due to wiper system failure, the wiper arm stops away from the stop position (impossible to return the arm to the stop position), the flight can continue in all safety without any speed restriction.
The pressure of the wiper arm-blade assembly is adjustable within the range of pressures corresponding to forces between 2 daN (4.4962 lbf) and 5.5 daN (12.3645 lbf); these are applied to the center of the blade perpendicular to the windshield plane.
Within these limits, there is no degradation of the system performance.
In all the utilization conditions (normal or abnormal operation of the wiper system), rupture of one or several parts of this system will not result in damage to the aircraft structure or the engines.
If, due to wiper system failure, the wiper arm stops away from the stop position (impossible to return the arm to the stop position), the flight can continue in all safety without any speed restriction.
(b) Speed
The windshield wiper system operates satisfactorily until the aircraft speed is 200 kts.
The operation of the windshield wiper system is possible between 200 to 230 kts but its performance can be unsatisfactory. After the operation of the wipers at a speed higher than 230 kts, a check of the system performance is necessary.
The windshield wiper system operates satisfactorily until the aircraft speed is 200 kts.
The operation of the windshield wiper system is possible between 200 to 230 kts but its performance can be unsatisfactory. After the operation of the wipers at a speed higher than 230 kts, a check of the system performance is necessary.
B. Rain Repellent System
(1) Rain-repellent fluid can
(a) The pressurized can is attached to the aft-left wall of the cockpit.
(b) The can contains 475 cubic centimeters of usable rain-repellent fluid.
(c) The system is pressurized with nitrogen; the nitrogen pressure in the can when full is 5.8 +-0.4 bar or -+0.7 bar (84.1219 +-5.8015 psi or -+10.1526 psi).
(d) A valve held closed under the load of internal pressure seals the can. A thin pin is provided for displacement of the valve.
(2) Rain-repellent fluid-gage assembly
(a) The gage assembly forms the can receptacle. The can is mounted on the receptacle, valve downwards.
The receptacle includes the pin provided for unseating of the sealing valve of the can.
The receptacle includes the pin provided for unseating of the sealing valve of the can.
(b) A pressure gage indicates the pressure in the can and thereby the quantity of fluid in the can:
- green band: the pressure is sufficient,
- yellow band: the pressure is low.
(c) The fluid gage incorporates a 80 cubic centimeters transparent chamber from which the fluid level is visible. When the can is completely empty, the remaining nitrogen pressure and the fluid remaining in the gage are still sufficient for several flights before replacement of the can.
(d) A purge pushbutton located on the can serves to purge the lines of the system when the can is replaced.
(3) Solenoid valve
(a) Upon energization, the valve controls the flow of rain repellent fluid released to the nozzles by means of an incorporated electronic timing device.
The timing device, adjustable between 0.1 and 1.0 second, is set at 0.4 second.
The timing device, adjustable between 0.1 and 1.0 second, is set at 0.4 second.
(b) The solenoid valve is normally closed and is supplied with 28VDC nominal.
(4) Spray nozzle
(a) A single nozzle serves to spray the rain repellent fluid on the corresponding windshield.
(b) The nozzle has four orifices of small diameter.
(5) Rain-repellent blowout reservoir
(a) During application of the fluid onto the windshield, the reservoir provides an increase in transient air pressure which serves to purge the lines of the system after each application of the fluid.
(b) It constitutes a decantation reservoir :
- for the rain repellent fluid in the event of possible leakage of valves
- for water which could remain in the air bled from the air conditioning system and freeze on the nozzle orifices.
(c) The reservoir can serve as a test connector to check for absence of clogging of the nozzles, using an appropriate pressurization tool connected to the test valve of the reservoir.
(6) Purge check valves
(a) Each valve is designed to prevent fluid to flow to the rain-repellent blowout reservoir and to the air conditioning system.
(7) Test check valve
(a) Each valve is designed to prevent fluid to flow to the rain-repellent blowout reservoir and to the air conditioning system.
(b) The check valve is mainly provided to isolate the system located upstream (towards the air conditioning system) when the check of the nozzles is performed using a special pressurization tool which is connected to the rain-repellent blowout reservoir.
(8) Ground checks
(a) Check reading on the pressure gage fitted to the fluid gage assembly.
If the pointer appears in the yellow band identified REPLACE, approximately ten applications of fluid are left in the can before need of can replacement.
If the pointer appears in the yellow band identified REPLACE, approximately ten applications of fluid are left in the can before need of can replacement.
(b) When replacing the can, purge the system lines using the purge pushbutton located on the fluid gage assembly.
(c) Do not operate the system in dry weather conditions. In the event of inadvertent application on dry surfaces, wash at the earliest opportunity.
(d) Avoid projections of fluid onto the mucous membranes.
(9) Utilization in flight
(a) The rain-repellent system is used in heavy rain, more precisely when the wipers are not sufficient at high aircraft speed.
(b) One or two applications of the fluid are generally sufficient for one takeoff or approach and landing sequence; however, the number of applications is unrestricted so as to improve visibility, regardless of the fluid amount used.
(c) Never spray fluid on a dry windshield. In the event of inadvertent application, do not operate the wipers before the rain wets the windshield.
(10) Fluid leakage
The rain repellent fluid contains an odorant (pine), which makes it easy for the crew to detect a leak in the cockpit and apply the associated emergency procedure.
The rain repellent fluid contains an odorant (pine), which makes it easy for the crew to detect a leak in the cockpit and apply the associated emergency procedure.