A320 Series Landing Gear System Presentation

 Landing Gear System Presentation

 The A320 family aircraft are equipped with dual wheel main landing gear, which retracts inboard.

Gears and main doors are hydraulically operated and electrically controlled by two computers named Landing Gear Control and Interface Units (LGCIU).

The doors which are fitted to the landing gear struts are operated mechanically by the gear.

 A dual wheel nose landing gear retracts forward.

The Nose Landing Gear (NLG) has an oleo-pneumatic shock absorber.

The nose gear main doors operate hydraulically.

The fixed doors (aft doors and leg doors) are operated by the gear.

 The wheels of the main landing gear are equipped with:

- carbon brakes for efficient braking, even at high temperature,
- an anti-skid system  (A/SKID),
- an automatic braking system (AUTO/BRK),
- brake fans (optional),
- and an optional Tire Pressure Indicating System (TPIS).

 The A320 provides two braking modes:

- NORMAL braking,
- and ALTERNATE braking.

Normal braking is powered by the green hydraulic system.
Alternate braking, which includes the parking brake, is powered by the yellow hydraulic system.

All braking functions (normal braking control, anti-skid control, automatic braking and brake temperature indications) are controlled by a two channel Braking/Steering Control Unit (BSCU).

 The A318 also provides two braking modes:

- NORMAL braking,
- and ALTERNATE braking.

Normal braking functions are controlled by the Braking/Steering Control Unit (BSCU).

Alternate braking is controlled by the Alternate Braking Control Unit (ABCU) and receives anti-skid orders from the BSCU.

 The nose landing gear is equipped with nose wheel steering.

It is hydraulically operated by the green hydraulic system and electrically controlled by the BSCU.

On the A318, the nose landing gear is hydraulically operated by the yellow hydraulic system.

A downlock safety pin must be installed before maintenance operations.

 The ECAM WHEEL page displays indications for the:

- main landing gear and nose landing gear.
On the A318, the ECAM page has a new configuration for the landing gear indications.

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- nose and  main landing gear doors,
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- brake temperature given by the temperature sensors through the BSCU.

 In the center of the ECAM WHEEL page, green and amber messages can be displayed to provide normal and abnormal indications.

On the A318, as the alternate braking becomes electrically controlled and thanks to the new EIS, more information is displayed on the nose wheel steering and braking systems.

 The ECAM WHEEL page displays the NLG and MLG tire pressures when the optional Tire Pressure Indicating System is installed.

The system consists of pressure sensors and a Tire Pressure Indicating Unit (TPIU).

 On the A319, A320 and A321, the position of the spoilers is displayed at the bottom of the ECAM WHEEL page.

On the A318, it is displayed at the top of the ECAM WHEEL page.

 The landing gear panel contains switches and indicators for:

- the LDG GEAR,
- the AUTO/BRK,
- the BRK FAN,
- and the A/SKID & N/W STRG.

When autobrake is used, selection of LO, MED or MAX is made using these pushbutton switches.

The anti-skid and nose wheel steering switch controls both functions. The switch is normally left in the ON position.

 The landing gear selector lever located on the center instrument panel has two positions, UP and DOWN. The neutral position is replaced by a safety valve which isolates the landing gear system pressure line at high speed.

The red arrow warns the flight crew that the landing gear is not locked down when the aircraft is in landing configuration.

 The landing gear gravity extension handle is located on the center pedestal. It mechanically operates the doors and gear.

 The steering hand wheels are located on each side of the cockpit, so either pilot can taxi the aircraft. They control the nose wheel steering through the BSCU.

 The rudder pedals can also be used to steer the aircraft.

The rudder pedals are located on each side of the center pedestal.
Manual braking is provided using the top of the rudder pedals.

 The parking brake handle is located on the center pedestal.

It operates a rotary switch which electrically controls the parking brake application.

 This gage, which measures pressures from the alternate braking system and brake accumulator, is located on the main instrument panel.

 Up, down and unlock indications are associated with position indicators on the WHEEL page.

 The landing gear computers are located in the forward avionics bay.

Note that the TPIU is an option.

 On the A318, an Alternate Braking Control unit (ABCU) is added and the BSCU is replaced.

 The safety valve isolates the landing gear hydraulic lines from supply pressure when the aircraft speed is greater than 260 knots.

 The nose landing gear doors and each main landing gear door can be opened (and closed) independently on ground using their own ground door opening handle.

 The handle located on the electrical box allows the nose wheels to be isolated from the nose wheel steering for towing purposes.

 Using the MCDU (Multipurpose and Control Display Unit), you can have access to the CFDS (Centralized Fault Display System) fault messages of each landing gear system. Specific BITE tests are available as well.

The BSCU is a dual channel computer. The BSCU BITE stores fault messages of braking and nose wheel steering systems.

An Alternate Braking Control Unit (ABCU) is added on the A318.

On the MCDU SYSTEM REPORT/TEST L/G menu page, the TPIS line is always displayed, even if the system is not fitted on the aircraft.

 Using the MCDU (Multipurpose and Control Display Unit), you can have access to the CFDS (Centralized Fault Display System) fault messages of each landing gear system. Specific BITE tests are available as well.

The BSCU is a dual channel computer. The BSCU BITE stores fault messages of braking and nose wheel steering systems.

An Alternate Braking Control Unit (ABCU) is added on the A318.

On the MCDU SYSTEM REPORT/TEST L/G menu page, the TPIS line is always displayed, even if the system is not fitted on the aircraft.

 When you work on the landing gear system, make sure that you obey all the AMM safety procedures. This will prevent injury to persons and/or damage to the aircraft. Here is an overview of main safety precautions relative to the landing gear system.

When you perform any maintenance task, make sure that all circuits are isolated. Unwanted electrical or hydraulic power can be dangerous.

Make sure that the travel ranges of the landing gear and doors are clear. Movement of the landing gear and doors can cause injury and/or damage.

Make sure that the wheel chocks are in position, and the landing gear ground safety locks are installed. This prevents unwanted movement of the aircraft and landing gear.

Let the brakes and the wheels cool down before you go near the landing gear. Do not apply a liquid or gas fire extinguisher directly on a hot wheel or brake unit. This could cause an explosion.

Use only nitrogen for tire inflation. If the brakes overheat, other gases can cause an explosion.

During landing gear servicing, do not let high pressure gas get in contact with your skin. Gas bubbles in your blood can kill you.