DOC AIRBUS | AMM A320FALTERNATE BRAKING WITHOUT ANTI SKID - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The Alternate Braking without Anti Skid System is the secondary mode of operation of the Alternate Braking with Anti Skid System (Ref. AMM D/O 32-43-00-00).
The system uses the same electrohydraulic components as the Alternate Braking with the Anti Skid System with some additional special components.
The WHEEL page on the system display will show:
Braking inputs come from the Alternate Brake Pedal Transmitter Unit 103GG, located under Captain's pedals. When the brake pedals are operated, hydraulic pressure from the accumulator gives sufficient pressure for a minimum of seven full operations of the brakes. Pressure at the brakes is limited to a maximum pressure of 70 bar (1000 psi).
Braking is only possible via the alternate BPTU 103GG. When the brake pedals are operated, hydraulic pressure is supplied from the Yellow main hydraulic system (Ref. AMM D/O 29-13-00-00). If the Yellow system is not available, the pressure is supplied from the accumulator (filled from the Yellow system). The pressure is limited to 70 bar (1000 psi) and has sufficient pressure for a minimum of seven full operations of the brake pedals.
A triple pressure indicator 60GG in the cockpit shows:
The Alternate Braking without Anti Skid System is the secondary mode of operation of the Alternate Braking with Anti Skid System (Ref. AMM D/O 32-43-00-00).
The system uses the same electrohydraulic components as the Alternate Braking with the Anti Skid System with some additional special components.
The WHEEL page on the system display will show:
Braking inputs come from the Alternate Brake Pedal Transmitter Unit 103GG, located under Captain's pedals. When the brake pedals are operated, hydraulic pressure from the accumulator gives sufficient pressure for a minimum of seven full operations of the brakes. Pressure at the brakes is limited to a maximum pressure of 80 bar (1160 psi).
Braking is only possible via the alternate BPTU 103GG. When the brake pedals are operated, hydraulic pressure is supplied from the Yellow main hydraulic system (Ref. AMM D/O 29-13-00-00). If the Yellow system is not available, the pressure is supplied from the accumulator (filled from the Yellow system). The pressure is limited to 80 bar (1160 psi) and has sufficient pressure for a minimum of seven full operations of the brake pedals.
A triple pressure indicator 60GG in the cockpit shows:
** ON A/C NOT FOR ALL 
Alternate Braking without Anti Skid - SchematicThe Alternate Braking without Anti Skid System is the secondary mode of operation of the Alternate Braking with Anti Skid System (Ref. AMM D/O 32-43-00-00).
The system uses the same electrohydraulic components as the Alternate Braking with the Anti Skid System with some additional special components.
The WHEEL page on the system display will show:
- when the system is available
- the hydraulic supply available
Braking inputs come from the Alternate Brake Pedal Transmitter Unit 103GG, located under Captain's pedals. When the brake pedals are operated, hydraulic pressure from the accumulator gives sufficient pressure for a minimum of seven full operations of the brakes. Pressure at the brakes is limited to a maximum pressure of 70 bar (1000 psi).
Braking is only possible via the alternate BPTU 103GG. When the brake pedals are operated, hydraulic pressure is supplied from the Yellow main hydraulic system (Ref. AMM D/O 29-13-00-00). If the Yellow system is not available, the pressure is supplied from the accumulator (filled from the Yellow system). The pressure is limited to 70 bar (1000 psi) and has sufficient pressure for a minimum of seven full operations of the brake pedals.
A triple pressure indicator 60GG in the cockpit shows:
- the accumulator system pressure available (top gage)
- the pressure given at the brakes of the LH and RH MLG (bottom two gages).
The Alternate Braking without Anti Skid System is the secondary mode of operation of the Alternate Braking with Anti Skid System (Ref. AMM D/O 32-43-00-00).
The system uses the same electrohydraulic components as the Alternate Braking with the Anti Skid System with some additional special components.
The WHEEL page on the system display will show:
- when the system is available
- the hydraulic supply available
Braking inputs come from the Alternate Brake Pedal Transmitter Unit 103GG, located under Captain's pedals. When the brake pedals are operated, hydraulic pressure from the accumulator gives sufficient pressure for a minimum of seven full operations of the brakes. Pressure at the brakes is limited to a maximum pressure of 80 bar (1160 psi).
Braking is only possible via the alternate BPTU 103GG. When the brake pedals are operated, hydraulic pressure is supplied from the Yellow main hydraulic system (Ref. AMM D/O 29-13-00-00). If the Yellow system is not available, the pressure is supplied from the accumulator (filled from the Yellow system). The pressure is limited to 80 bar (1160 psi) and has sufficient pressure for a minimum of seven full operations of the brake pedals.
A triple pressure indicator 60GG in the cockpit shows:
- the accumulator system pressure available (top gage)
- the pressure given at the brakes of the LH and RH MLG (bottom two gages).
2. Component Location
** ON A/C NOT FOR ALL | FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C NOT FOR ALL | |||||
| 60GG | IND-BRK YELLOW PRESS TRIPLE | 400VU | 212 | 32-44-21 | |
| 100GG | PRESS XDCR-BRK, YELLOW R | 671 | 32-44-19 | ||
| 101GG | PRESS XDCR-BRK, YELLOW L | 571 | 32-44-19 | ||
| 2582GM | ACCU-BRK YELLOW PRESS | 148 | 32-44-11 | ||
| 2585GM | BRAKE ACCU PRESS GAGE | 198 | 32-44-14 | ||
| 2586GM | N2 CHARGING VALVE | 198 | 32-44-13 | ||
3. System Description
The system uses the same hydraulic and electrohydraulic components as specified in the Alternate Braking with Anti Skid system (Ref. AMM D/O 32-43-00-00).
The Alternate HP Manifold Assembly 3016GM connects the hydraulic supply (from the Yellow system or the accumulator) to the downstream components. This manifold has a check valve and a pressure relief valve. The check valve prevents the flow of fluid from the accumulator to the Yellow supply line. The pressure relief valve releases any system pressure of more than a given limit. This valve also includes a manual depressurization button which will release all the system pressure during system maintenance.
A pressure transducer 3068GN attached to the manifold measures the system pressure available. It transmits this data to the triple pressure indicator 60GG(in the cockpit) and the ABCU.
The alternate brake selector valve 99GG controls the supply of the available hydraulic pressure to the two Alternate Braking Manifolds.
The alternate brake manifolds have a pressure transducer.It measures the pressure supplied to the brakes (downstream of the safety valves) and transmits this data to the triple pressure indicator, the ABCU and the BSCU.
** ON A/C NOT FOR ALL The system uses the same hydraulic and electrohydraulic components as specified in the Alternate Braking with Anti Skid system (Ref. AMM D/O 32-43-00-00).
The Alternate HP Manifold Assembly 3016GM connects the hydraulic supply (from the Yellow system or the accumulator) to the downstream components. This manifold has a check valve and a pressure relief valve. The check valve prevents the flow of fluid from the accumulator to the Yellow supply line. The pressure relief valve releases any system pressure of more than a given limit. This valve also includes a manual depressurization button which will release all the system pressure during system maintenance.
A pressure transducer 3068GN attached to the manifold measures the system pressure available. It transmits this data to the triple pressure indicator 60GG(in the cockpit) and the ABCU.
The alternate brake selector valve 99GG controls the supply of the available hydraulic pressure to the two Alternate Braking Manifolds.
The alternate brake manifolds have a pressure transducer.It measures the pressure supplied to the brakes (downstream of the safety valves) and transmits this data to the triple pressure indicator, the ABCU and the BSCU.
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
6. Component Description
A. Triple Pressure Indicator FIN: 60-GG
The triple pressure indicator has three dials on its front face. The top gage shows the system hydraulic pressure available (Yellow hydraulic system or accumulator), and the bottom two gages show the hydraulic pressures:
The green zone on the brake gages goes from 0 to 1000 psi. When the anti-skid is not available, the brake pressure must be less than 1000 psi to prevent wheel locking and tire burst. You must only use the green band if there is an alternate braking without anti-skid.
The indicator is installed in an octagonal case and has an electrical connection at the rear. Each pressure indication is operated with a galvanometer. A printed circuit board gives a stabilized power supply and is used for the adjustment of the galvanometers.
The triple pressure indicator has three dials on its front face. The top gage shows the system hydraulic pressure available (Yellow hydraulic system or accumulator), and the bottom two gages show the hydraulic pressures:
- That go to the left MLG brakes,
- That go to the right MLG brakes.
The green zone on the brake gages goes from 0 to 1000 psi. When the anti-skid is not available, the brake pressure must be less than 1000 psi to prevent wheel locking and tire burst. You must only use the green band if there is an alternate braking without anti-skid.
The indicator is installed in an octagonal case and has an electrical connection at the rear. Each pressure indication is operated with a galvanometer. A printed circuit board gives a stabilized power supply and is used for the adjustment of the galvanometers.
B. Brake Yellow Pressure Accumulator 2582GM
The accumulator is an oleo-pneumatic unit that keeps a specified volume of pressurized hydraulic fluid in it.
It has a steel body which contains a flexible bladder. An inlet connector permits the bladder to be pressurized with nitrogen. A nozzle assembly, which includes a spring and a poppet valve, lets pressurized hydraulic fluid go into the body. The bladder keeps the nitrogen and hydraulic fluid apart.
When the fluid chamber is not pressurized, the nitrogen pressure expands the bladder until it touches the poppet valve. The poppet valve closes to keep the bladder in the body. When the fluid chamber is pressurized, the bladder size decreases until the pressures in the gas and fluid chambers are equal. The spring keeps the poppet valve open. As the pressure at the fluid inlet decreases, the bladder expands and forces the hydraulic fluid from the fluid chamber.
The accumulator is an oleo-pneumatic unit that keeps a specified volume of pressurized hydraulic fluid in it.
It has a steel body which contains a flexible bladder. An inlet connector permits the bladder to be pressurized with nitrogen. A nozzle assembly, which includes a spring and a poppet valve, lets pressurized hydraulic fluid go into the body. The bladder keeps the nitrogen and hydraulic fluid apart.
When the fluid chamber is not pressurized, the nitrogen pressure expands the bladder until it touches the poppet valve. The poppet valve closes to keep the bladder in the body. When the fluid chamber is pressurized, the bladder size decreases until the pressures in the gas and fluid chambers are equal. The spring keeps the poppet valve open. As the pressure at the fluid inlet decreases, the bladder expands and forces the hydraulic fluid from the fluid chamber.
C. Pressure Transducer 100GG (101GG)
Refer for description to 32-43-00-00
Refer for description to 32-43-00-00
7. Operation/Control and Indicating
The system is active when the WHEEL page shows that the anti skid function is not available ( ANTI SKID legend in amber). When a braking input is made at the brake pedals it causes an output from the active transmitter unit (BPTU). The transmitter unit 103GG at the Captain position sends its outputs to the ABCU.
The braking inputs cause the ABCU to energize the alternate brake selector valve 99GG to let hydraulic pressure go into the system. When this occurs, the components in the system downstream of the selector valve operate as described in 32-43-00. The alternate servo valves (Direct Drive Valves) are controlled to give a maximum brake pressure of 70 bars (1000 psi).
When the brake pedals are released:
The system is active when the WHEEL page shows that the anti skid function is not available ( ANTI SKID legend in amber). When a braking input is made at the brake pedals it causes an output from the active transmitter unit (BPTU). The transmitter unit 103GG at the Captain position sends its outputs to the ABCU.
The braking inputs cause the ABCU to energize the alternate brake selector valve 99GG to let hydraulic pressure go into the system. When this occurs, the components in the system downstream of the selector valve operate as described in 32-43-00. The alternate servovalves (Direct Drive Valves) are controlled to give a maximum brake pressure of 80 bar (1160 psi).
When the brake pedals are released:
The system is active when the WHEEL page shows that the anti skid function is not available ( ANTI SKID legend in amber). When a braking input is made at the brake pedals it causes an output from the active transmitter unit (BPTU). The transmitter unit 103GG at the Captain position sends its outputs to the ABCU.
The braking inputs cause the ABCU to energize the alternate brake selector valve 99GG to let hydraulic pressure go into the system. When this occurs, the components in the system downstream of the selector valve operate as described in 32-43-00. The alternate servo valves (Direct Drive Valves) are controlled to give a maximum brake pressure of 70 bars (1000 psi).
When the brake pedals are released:
- If the Yellow hydraulic supply is available, the brake selector valve is de-energized to stop the hydraulic supply.
- The alternate servo valves (Direct Drive Valves) are de-energized to connect the brake service lines to the return manifold.
- If the Yellow hydraulic supply is not available, the hydraulic power comes from the brake accumulator (emergency system).The ABCU continues to signal the alternate brake selector valve 99GG open and energizes the direct drive valve to keep the demanded pressure equal to the Zero Torque Pressure (ZTP mode). The purpose of this function is to prevent the loss of hydraulic fluid from the accumulator that could be caused by repeated brake bleeding/re-filling.
The ZTP mode will be stopped as soon as the emergency braking is de-activated or when: - The Yellow hydraulic supply is available again or
- The parking brake is set to ON or
- The tow control lever on the NLG is set to de-activate the Nose Wheel Steering.
The system is active when the WHEEL page shows that the anti skid function is not available ( ANTI SKID legend in amber). When a braking input is made at the brake pedals it causes an output from the active transmitter unit (BPTU). The transmitter unit 103GG at the Captain position sends its outputs to the ABCU.
The braking inputs cause the ABCU to energize the alternate brake selector valve 99GG to let hydraulic pressure go into the system. When this occurs, the components in the system downstream of the selector valve operate as described in 32-43-00. The alternate servovalves (Direct Drive Valves) are controlled to give a maximum brake pressure of 80 bar (1160 psi).
When the brake pedals are released:
- If the Yellow hydraulic supply is available, the brake selector valve is de-energized to stop the hydraulic supply.
- The alternate servovalves (Direct Drive Valves) are de-energized to connect the brake service lines to the return manifold.
- If the Yellow hydraulic supply is not available, the hydraulic power comes from the brake accumulator (emergency system).The ABCU continues to signal the alternate brake selector valve 99GG open and energizes the direct drive valve to keep the demanded pressure equal to the Zero Torque Pressure (ZTP mode). The purpose of this function is to prevent the loss of hydraulic fluid from the accumulator that could be caused by repeated brake bleeding/re-filling.
The ZTP mode will be stopped as soon as the emergency braking is de-activated or when: - The Yellow hydraulic supply is available again or
- The parking brake is set to ON or
- The tow control lever on the NLG is set to de-activate the Nose Wheel Steering.