DOC AIRBUS | AMM A320FHYDRAULIC FLUID QUANTITY INDICATING - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The hydraulic quantity indicating system has two functions. They are
** ON A/C NOT FOR ALL The hydraulic quantity indicating system has two functions. They are
- to show the fluid contents of each reservoir for the flight crew and maintenance personnel,
- to send signals to the Electronic Centralized Aircraft Monitor (ECAM) system and the overhead panel when the contents of any reservoir is less than a specified minimum.
2. Component Location
** ON A/C NOT FOR ALL 
Component Location| FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C ALL | |||||
| 1834GQ | HYD RESERV QTY INDICATOR | 197CB | 197 | 29-31-21 | |
3. System Description
Each reservoir has a gage-transmitter which gives a visual indication and sends electrical signals to show the fluid contents. The unit is a float assembly connected mechanically to a synchro transmitter. The pointer of the mechanical contents gage is connected to the synchro transmitter. When the float moves, the synchro transmitter and the pointer turn together. The synchro transmitter sends signals to the ECAM system and to the reservoir quantity indicator on the Green ground-service panel.
A reservoir quantity indicator is installed on the Green ground-service panel. It operates together with the filling selector valve and shows the contents of the reservoir which the selector valve is set to.
Each reservoir also has a float assembly which operates a switch. The float operates the switch at a specified level (between 2.0 and 2.3 l in the Blue reservoir and between 2.6 and 3.4 l in the Green and Yellow reservoirs), and shows that the fluid contents are dangerously low.
The contents of the hydraulic reservoirs are shown
The low level switches send signals to the ECAM system and to the overhead panel.
** ON A/C NOT FOR ALL Each reservoir has a gage-transmitter which gives a visual indication and sends electrical signals to show the fluid contents. The unit is a float assembly connected mechanically to a synchro transmitter. The pointer of the mechanical contents gage is connected to the synchro transmitter. When the float moves, the synchro transmitter and the pointer turn together. The synchro transmitter sends signals to the ECAM system and to the reservoir quantity indicator on the Green ground-service panel.
A reservoir quantity indicator is installed on the Green ground-service panel. It operates together with the filling selector valve and shows the contents of the reservoir which the selector valve is set to.
Each reservoir also has a float assembly which operates a switch. The float operates the switch at a specified level (between 2.0 and 2.3 l in the Blue reservoir and between 2.6 and 3.4 l in the Green and Yellow reservoirs), and shows that the fluid contents are dangerously low.
The contents of the hydraulic reservoirs are shown
- on a mechanically-operated gage on each reservoir,
- on an electrical reservoir quantity indicator on the ground-service panel of the Green system,
- on the ECAM system display (HYD page).
The low level switches send signals to the ECAM system and to the overhead panel.
4. Power Supply
The AC bus 131XPA supplies 26 V AC through the circuit breaker 1831GQ. It is used for synchro excitation of the synchro transmitters. The same 26 V AC supply is used for excitation of the synchro in the reservoir quantity indicator on the Green ground-service panel. The reservoir quantity indicator has light emitting diodes (LED) and filament lamps which use the same supply. The DC bus 103PP supplies 28 V DC through circuit breaker 1832GQ to the three low level switches in the reservoirs.
** ON A/C NOT FOR ALL The AC bus 131XPA supplies 26 V AC through the circuit breaker 1831GQ. It is used for synchro excitation of the synchro transmitters. The same 26 V AC supply is used for excitation of the synchro in the reservoir quantity indicator on the Green ground-service panel. The reservoir quantity indicator has light emitting diodes (LED) and filament lamps which use the same supply. The DC bus 103PP supplies 28 V DC through circuit breaker 1832GQ to the three low level switches in the reservoirs.
5. Component Description
A. Low Level Switch
The low level switch is installed in the reservoir and gives a signal when the fluid level is too low. It is a float-operated switch which includes a relay. The float assembly includes a magnet which keeps the contacts of a reed switch open when the float is high. When the level of the fluid decreases, the float falls and the reed switch closes. This causes the relay to operate and a signal is sent to the system data acquisition concentrator (SDAC) and to the overhead panel.
A metal shroud is around the float. This shroud operates as a damper of small changes in the level of the fluid.
The low level switch is installed in the reservoir and gives a signal when the fluid level is too low. It is a float-operated switch which includes a relay. The float assembly includes a magnet which keeps the contacts of a reed switch open when the float is high. When the level of the fluid decreases, the float falls and the reed switch closes. This causes the relay to operate and a signal is sent to the system data acquisition concentrator (SDAC) and to the overhead panel.
A metal shroud is around the float. This shroud operates as a damper of small changes in the level of the fluid.
B. Reservoir Quantity Indicator 1834GQ
The reservoir quantity indicator is installed on the ground-service panel of the Green system. It shows the contents of the reservoir which the filling selector valve is set to.
The indicator has a cylindrical case which contains a synchro. On one end of the case there is the electrical receptacle. The indicator face is on the other end. The indicator has three colored scales (one for each reservoir) and three lights which show which system the indicator is set to. Lighting of the indicator face is given with three lights installed in the indicator. The Green and Yellow system indicators are LEDs. The Blue system indicator is a filament lamp or an LED. All of the other lights are filament lamps.
The reservoir quantity indicator is installed on the ground-service panel of the Green system. It shows the contents of the reservoir which the filling selector valve is set to.
The indicator has a cylindrical case which contains a synchro. On one end of the case there is the electrical receptacle. The indicator face is on the other end. The indicator has three colored scales (one for each reservoir) and three lights which show which system the indicator is set to. Lighting of the indicator face is given with three lights installed in the indicator. The Green and Yellow system indicators are LEDs. The Blue system indicator is a filament lamp or an LED. All of the other lights are filament lamps.
6. Operation
Changes in the level of fluid in the reservoir cause the float of the transmitter to move the arm assembly. The arm turns its pivot which is connected with gears to the first permanent magnet. Magnetic influence transmits the movement to the second permanent magnet. The second magnet turns the synchro rotor which sends a signal to the ECAM system and to the reservoir filling selector. At the same time the pointer on the synchro gives a visual indication of the contents of the reservoir. The ECAM system gets the signal from the synchro and changes it to an analog display of the contents of the reservoir.
The reservoir filling selector gets the signals from all three of the synchros. When it is set to one of the three systems, the signal from the applicable synchro is sent to the reservoir quantity indicator. The applicable system indicator light comes on and the contents of that reservoir are shown on the reservoir quantity indicator.
If the quantity of hydraulic fluid is below a specified minimum, the float of the low level switch operates the switch. Discrete signals are sent to the SDAC and to the overhead panel. The SDAC makes these warnings come on:
The signal to the overhead panel makes the applicable FAULT annunciator(s) come on.
If the low level switch does not operate, the SDAC uses the data from the contents transmitter to start low level warning procedure. The warning is generated when the transmitter data show that the contents are below the low level switch threshold. The SDAC makes the warnings occur when the content of the reservoirs are 2.5 l (0.6604 USgal) (Green And Yellow reservoirs) or 1.8 l (0.4755 USgal) (Blue reservoir). In this case, there will be no FAULT indication on the overhead panel.
Changes in the level of fluid in the reservoir cause the float of the transmitter to move the arm assembly. The arm turns its pivot which is connected with gears to the first permanent magnet. Magnetic influence transmits the movement to the second permanent magnet. The second magnet turns the synchro rotor which sends a signal to the ECAM system and to the reservoir filling selector. At the same time the pointer on the synchro gives a visual indication of the contents of the reservoir. The ECAM system gets the signal from the synchro and changes it to an analog display of the contents of the reservoir.
The reservoir filling selector gets the signals from all three of the synchros. When it is set to one of the three systems, the signal from the applicable synchro is sent to the reservoir quantity indicator. The applicable system indicator light comes on and the contents of that reservoir are shown on the reservoir quantity indicator.
If the quantity of hydraulic fluid is below a specified minimum, the float of the low level switch operates the switch. Discrete signals are sent to the SDAC and to the overhead panel. The SDAC makes these warnings come on:
- a low level warning on the engine/warning display,
- the MASTER CAUT attention getter,
- a single-chime audio warning.
The signal to the overhead panel makes the applicable FAULT annunciator(s) come on.
If the low level switch does not operate, the SDAC uses the data from the contents transmitter to start low level warning procedure. The warning is generated when the transmitter data show that the contents are below the low level switch threshold. The SDAC makes the warnings occur when the content of the reservoirs are 2.5 l (0.6604 USgal) (Green And Yellow reservoirs) or 1.8 l (0.4755 USgal) (Blue reservoir). In this case, there will be no FAULT indication on the overhead panel.