DOC AIRBUS | AMM A320FWHEELS AND BRAKES - 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
** ON A/C NOT FOR ALL
1. General
The wheels and their related system of brakes let you control the movement of the aircraft on the ground.
The wheels are described in chapter 32-41-00.
There are two brake systems (normal and alternate) that can independently operate the brake units. The alternate system has diferent modes of operation. The systems and their modes of control and operation are given in the chapters that follow:
The brake systems have a computer which has Built-In Test Equipment (BITE). This continuously monitors the operation of the brake and steering systems (Ref. AMM D/O 32-46-00-00).
The brake units include a Brake Temperature Monitoring System (Ref. AMM D/O 32-47-00-00).
The wheels include a Tire Pressure Indicating System (optional)
(Ref. AMM D/O 32-49-00-00).
** ON A/C NOT FOR ALL The wheels and their related system of brakes let you control the movement of the aircraft on the ground.
The wheels are described in chapter 32-41-00.
There are two brake systems (normal and alternate) that can independently operate the brake units. The alternate system has diferent modes of operation. The systems and their modes of control and operation are given in the chapters that follow:
- Normal Braking (Ref. AMM D/O 32-42-00-00).
- Alternate Braking with Anti Skid (Ref. AMM D/O 32-43-00-00).
- Alternate Braking without Anti Skid (Ref. AMM D/O 32-44-00-00).
- Parking/Ultimate Emergency Braking (Ref. AMM D/O 32-45-00-00).
The brake systems have a computer which has Built-In Test Equipment (BITE). This continuously monitors the operation of the brake and steering systems (Ref. AMM D/O 32-46-00-00).
The brake units include a Brake Temperature Monitoring System (Ref. AMM D/O 32-47-00-00).
The wheels include a Tire Pressure Indicating System (optional)
(Ref. AMM D/O 32-49-00-00).
2. Component Location
Not applicable
** ON A/C NOT FOR ALL Not applicable
Brake system - SchematicA. Wheels (Ref: 32-41-00)
The wheels are made of two half wheels machined from aluminium alloy forgings and have a radial tubeless tire installed .It is possible to use conventional (bias ply) tires as an option.
The wheels are made of two half wheels machined from aluminium alloy forgings and have a radial tubeless tire installed .It is possible to use conventional (bias ply) tires as an option.
B. Normal Braking (Ref. 32-42-00)
The Normal braking system is electrohydraulic and includes a computer, which is the Braking / Steering Control Unit (BSCU). The BSCU controls the operation of the electrohydraulic valves in the system to decrease the speed of the aircraft. The hydraulic pressure that operates the brake pistons is supplied from the Green Main Hydraulic Power system (Ref. AMM D/O 29-11-00-00).
The system has two modes of operation, manual and automatic, and gives automatic anti skid protection in each mode. Each brake unit gets separate pressure control to supply the anti skid protection. The WHEEL page shows when the anti skid function operates. A switch (A/SKID) in the cockpit lets you cancel the system. If the switch is set to OFF, brake operation will go to the Alternate Braking Without Anti Skid system (Ref. AMM D/O 32-44-00-00).
During manual braking, the input signals to the computer come from the two pairs of brake pedals (through the related transmitter unit) in the flight deck. Thus the quantity of hydraulic pressure that goes to the brake units is in proportion to the travel of each related brake pedal. Each pedal independently controls braking to the related MLG.
Three pushbutton switches in the cockpit set the auto braking to be used during a landing.There are three deceleration modes (LO, MED or MAX).MAX mode is selected before Take-off.
If a brake pedal supplies an input signal which is more than the set auto value it cancels the automatic braking program.
If specified failures occur in the system, control automatically changes to the Alternate Braking system (Ref. 32-43-00) or (Ref. 32-44-00).
The Normal braking system is electrohydraulic and includes a computer, which is the Braking / Steering Control Unit (BSCU). The BSCU controls the operation of the electrohydraulic valves in the system to decrease the speed of the aircraft. The hydraulic pressure that operates the brake pistons is supplied from the Green Main Hydraulic Power system (Ref. AMM D/O 29-11-00-00).
The system has two modes of operation, manual and automatic, and gives automatic anti skid protection in each mode. Each brake unit gets separate pressure control to supply the anti skid protection. The WHEEL page shows when the anti skid function operates. A switch (A/SKID) in the cockpit lets you cancel the system. If the switch is set to OFF, brake operation will go to the Alternate Braking Without Anti Skid system (Ref. AMM D/O 32-44-00-00).
During manual braking, the input signals to the computer come from the two pairs of brake pedals (through the related transmitter unit) in the flight deck. Thus the quantity of hydraulic pressure that goes to the brake units is in proportion to the travel of each related brake pedal. Each pedal independently controls braking to the related MLG.
Three pushbutton switches in the cockpit set the auto braking to be used during a landing.There are three deceleration modes (LO, MED or MAX).MAX mode is selected before Take-off.
If a brake pedal supplies an input signal which is more than the set auto value it cancels the automatic braking program.
If specified failures occur in the system, control automatically changes to the Alternate Braking system (Ref. 32-43-00) or (Ref. 32-44-00).
C. Alternate Braking with Anti Skid (Ref. 32-43-00)
The Alternate braking system with anti skid is the secondary, electrohydraulic braking system. It automatically becomes available if:
An analog computer ABCU (Alternate Braking Control Unit) controls the operation of the alternate braking system.
Braking inputs can only be made at the brake pedals and the BSCU provides the anti-skid control (Ref. AMM D/O 32-42-00-00). The hydraulic pressure that goes to the second set of pistons in the brakes (Ref. AMM D/O 32-42-00-00) is supplied from the Yellow Main Hydraulic Power supply (Ref. AMM D/O 29-13-00-00). The quantity of hydraulic pressure that goes to the brake units is in proportion to the travel of each related brake pedal. Each pair of brake units (on the same gear) get separate pressure control to supply the anti skid function.
The Alternate braking system with anti skid is the secondary, electrohydraulic braking system. It automatically becomes available if:
- specified failures occur in the Normal braking system (Ref. AMM D/O 32-42-00-00)
- the pressure of the Green main hydraulic power supply (Ref. AMM D/O 29-11-00-00) is less than a specified value.
An analog computer ABCU (Alternate Braking Control Unit) controls the operation of the alternate braking system.
Braking inputs can only be made at the brake pedals and the BSCU provides the anti-skid control (Ref. AMM D/O 32-42-00-00). The hydraulic pressure that goes to the second set of pistons in the brakes (Ref. AMM D/O 32-42-00-00) is supplied from the Yellow Main Hydraulic Power supply (Ref. AMM D/O 29-13-00-00). The quantity of hydraulic pressure that goes to the brake units is in proportion to the travel of each related brake pedal. Each pair of brake units (on the same gear) get separate pressure control to supply the anti skid function.
D. Alternate Braking without Anti Skid (Ref. 32-44-00)
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 is automatically available when the anti skid function is not available. This occurs when:
The system uses the same hydromechanical components as the Alternate braking with anti skid system.If the Yellow Hydraulic Power supply is lost, the accumulator (filled from the Yellow HP) gives sufficient power for at least seven full brake application.
A triple pressure indicator in the cockpit shows the braking accumulator pressure and the pressure at the brakes.
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 is automatically available when the anti skid function is not available. This occurs when:
- the A/SKID switch is set to OFF
- the Yellow Main Hydraulic Power supply is not available.
- the Anti skid function of the BSCU is faulty.
The system uses the same hydromechanical components as the Alternate braking with anti skid system.If the Yellow Hydraulic Power supply is lost, the accumulator (filled from the Yellow HP) gives sufficient power for at least seven full brake application.
A triple pressure indicator in the cockpit shows the braking accumulator pressure and the pressure at the brakes.
E. Parking/Ultimate Emergency Braking (Ref. 32-45-00)
The parking brake system is an electrohydraulic system. It uses the components of the alternate braking system to send pressure to the brakes. Its primary function is to prevent movement of the aircraft when it is parked. It can also be used to stop the aircraft during towing or in an emergency.
The parking brake system gets its hydraulic power supply from the accumulator of the Alternate braking system (Ref. AMM D/O 32-44-00-00) or the Yellow Main Hydraulic Power system (Ref. AMM D/O 29-13-00-00). The accumulators have sufficient capacity to hold the brakes on for a minimum time of twelve hours.
The brake pressure supplied to each MLG and the hydraulic pressure available to the system are shown on the triple pressure indicator (Ref. AMM D/O 32-44-00-00). .
The parking brake system is an electrohydraulic system. It uses the components of the alternate braking system to send pressure to the brakes. Its primary function is to prevent movement of the aircraft when it is parked. It can also be used to stop the aircraft during towing or in an emergency.
The parking brake system gets its hydraulic power supply from the accumulator of the Alternate braking system (Ref. AMM D/O 32-44-00-00) or the Yellow Main Hydraulic Power system (Ref. AMM D/O 29-13-00-00). The accumulators have sufficient capacity to hold the brakes on for a minimum time of twelve hours.
The brake pressure supplied to each MLG and the hydraulic pressure available to the system are shown on the triple pressure indicator (Ref. AMM D/O 32-44-00-00). .
F. Brakes and Steering Built-in Test Equipment (Ref. 32-46-00)
The BSCU includes hardware and software which:
The BSCU includes hardware and software which:
- continuously monitors the systems for failures
- does automatic system tests at specified times
- permits specified system tests during ground maintenance.
G. Brake System Temperature Monitoring System (Ref. 32-47-00)
The system continuously measures the temperature of each brake. It has a sensor on each brake and a Brake Temperature Monitoring Unit (BTMU) for each pair of brakes.
The brake temperatures are shown on the WHEEL page. When a brake becomes too hot:
The system continuously measures the temperature of each brake. It has a sensor on each brake and a Brake Temperature Monitoring Unit (BTMU) for each pair of brakes.
The brake temperatures are shown on the WHEEL page. When a brake becomes too hot:
- the EWD gives a warning message and instructions (during specified flight phases)
- the MASTER CAUT lights come on
- an aural warning is given.
H. Tire Pressure Indicating System (TPIS) (Ref. 32-49-00) (optional)
The TPIS automatically monitors the landing-gear tire pressures and continuously shows the values on the WHEEL page.
The system includes an electronic pressure sensor in each wheel and a Tire Pressure Indicating Computer (TPIC). The TPIC controls the operation of the system and sends data to other systems in the aircraft. It supplies data and warnings if the pressures are unsatisfactory.
The TPIS automatically monitors the landing-gear tire pressures and continuously shows the values on the WHEEL page.
The system includes an electronic pressure sensor in each wheel and a Tire Pressure Indicating Computer (TPIC). The TPIC controls the operation of the system and sends data to other systems in the aircraft. It supplies data and warnings if the pressures are unsatisfactory.
4. Power Supply
B. Hydraulic Power Supplies
Refer to 29-11-00 and 29-13-00
Refer to 29-11-00 and 29-13-00
** ON A/C NOT FOR ALL
6. Component Description
A. Operation/Control FIN: 10-GG
(1) Normal braking (Ref. AMM D/O 32-42-00-00)
In the manual braking mode, operation of the brake pedals causes a signal to be sent to the BSCU. The BSCU energizes the brake selector valve and the servovalves which supply the correct pressure to the brake units (Ref. 32-42-00). The BSCU automatically releases the pressure (servovalve control) in the necessary brakes during anti skid control.
In the automatic braking mode the BSCU uses the braking program that is set to control the rate of the aircrafts deceleration. The BSCU starts the braking program when the necessary specified conditions are available. It calculates the correct brake pressure required and controls the servovalves to get the correct deceleration rate.
The BSCU also controls the anti skid function. To do this it compares the actual wheel speeds with the aircraft speed. The BSCU then releases the brake of the wheel that starts to be in a skid condition.
The BSCU also puts the brakes on for a short time during retraction of the landing gear.
In the manual braking mode, operation of the brake pedals causes a signal to be sent to the BSCU. The BSCU energizes the brake selector valve and the servovalves which supply the correct pressure to the brake units (Ref. 32-42-00). The BSCU automatically releases the pressure (servovalve control) in the necessary brakes during anti skid control.
In the automatic braking mode the BSCU uses the braking program that is set to control the rate of the aircrafts deceleration. The BSCU starts the braking program when the necessary specified conditions are available. It calculates the correct brake pressure required and controls the servovalves to get the correct deceleration rate.
The BSCU also controls the anti skid function. To do this it compares the actual wheel speeds with the aircraft speed. The BSCU then releases the brake of the wheel that starts to be in a skid condition.
The BSCU also puts the brakes on for a short time during retraction of the landing gear.
(2) Alternate braking with anti skid (Ref. AMM D/O 32-43-00-00)
When the brake pedals are operated a signal is sent to the ABCU. The ABCU controls the system pressure that goes to the brakes. In the anti skid function, the BSCU sends anti skid currents to the ABCU which substracts them to the pressure control currents sent to the Alternate Servovalve (Direct Drive Valve) to release the pressure to prevent wheel locking.
When the brake pedals are operated a signal is sent to the ABCU. The ABCU controls the system pressure that goes to the brakes. In the anti skid function, the BSCU sends anti skid currents to the ABCU which substracts them to the pressure control currents sent to the Alternate Servovalve (Direct Drive Valve) to release the pressure to prevent wheel locking.
(3) Alternate braking without anti skid (Ref. AMM D/O 32-44-00-00)
When the brake pedals are operated a signal is sent to the ABCU.The ABCU controls the Direct Drive Valves in the system to set the necessary pressure at each pair of brake units.
When the brake pedals are operated a signal is sent to the ABCU.The ABCU controls the Direct Drive Valves in the system to set the necessary pressure at each pair of brake units.
(4) Parking braking (Ref. AMM D/O 32-45-00-00)
When the PARK BRK control switch is set to ON (applied) it sends an electrical signal to energise an electrohydraulic control valve.The other braking modes are disconnected, the brakes are supplied with Yellow high pressure or accumulator pressure.
The parking brake control valve limits the pressure.
The CONFIG PARKING BRAKE ON message appears on the upper ECAM DU when:
When the PARK BRK control switch is set to ON (applied) it sends an electrical signal to energise an electrohydraulic control valve.The other braking modes are disconnected, the brakes are supplied with Yellow high pressure or accumulator pressure.
The parking brake control valve limits the pressure.
The CONFIG PARKING BRAKE ON message appears on the upper ECAM DU when:
- the parking-brake control switch is in the ON (applied) position
- one engine is at full throttle.
(5) Ground Tests and BITE (Ref. AMM D/O 32-46-00-00)
The BITE function of the braking/steering control unit (BSCU) permanently monitors the electrical control and regulation functions .
The faults found are memorized and shown on the CFDIU.
The BITE function of the braking/steering control unit (BSCU) permanently monitors the electrical control and regulation functions .
The faults found are memorized and shown on the CFDIU.
(6) Brake system temperature monitoring system (Ref. AMM D/O 32-47-00-00)
The brake temperature system measures the temperature at each of the four brakes
The sensor on each brake sends analog signals to the related BTMU.
The BTMU sends the signals to the BSCU.The BSCU changes the analog data to ARINC data and sends it to the EIS.
The temperature values are shown on the lower ECAM DU.
The brake temperature system measures the temperature at each of the four brakes
The sensor on each brake sends analog signals to the related BTMU.
The BTMU sends the signals to the BSCU.The BSCU changes the analog data to ARINC data and sends it to the EIS.
The temperature values are shown on the lower ECAM DU.
(7) Brake Cooling Fans (Ref. AMM D/O 32-48-00-00) (Optional)
The brake cooling fans permit high speed cooling of the brakes.They thus decrease the turnaround time of the aircraft if you make short flights with high energy braking.One fan is installed on each wheel of the main gear.
A BRK FAN pushbutton switch is used to operate the fans.When the brakes are hot, the HOT legend of the pusbutton switch comes on.
The brake cooling fans permit high speed cooling of the brakes.They thus decrease the turnaround time of the aircraft if you make short flights with high energy braking.One fan is installed on each wheel of the main gear.
A BRK FAN pushbutton switch is used to operate the fans.When the brakes are hot, the HOT legend of the pusbutton switch comes on.
(8) Tire pressure indicating system (TPIS) (Ref. AMM D/O 32-49-00-00) (Optional)
The TPIS shows the pressure of the tires of the main gear and nose gear on the lower ECAM DU.
The TPIS shows the pressure of the tires of the main gear and nose gear on the lower ECAM DU.
7. Operation/Control and Indicating
The BSCU (Ref. AMM D/O 32-42-00-00) includes hardware and software to:
For the description of these functions (Ref. AMM D/O 32-46-00-00).
The BSCU (Ref. AMM D/O 32-42-00-00) includes hardware and software to:
- do a power-up test of parts of the system when the system is energized
- continuously monitor the system for failures
- keep a record of the failures
- send the failure data to the CFDS.
- do specified tests of part of the system at specified times
- do specified tests during ground maintenance.
For the description of these functions (Ref. AMM D/O 32-46-00-00).