WHEEL page
FCOM DSC-32-10-40 P 4–5 · DSC-32-30-20 P 6–9 · PRO-ABN-BRAKES
WHEEL page
- Each gear has two triangles: the left from LGCIU 1, the right from LGCIU 2. One green triangle per gear confirms it is down and locked.
- AUTO BRK and the armed mode show in green.
- Red triangles: gear in transit. Amber doors: open. Once the gear is up and locked the triangles go, and each closed door shows a green line.
- The main wheels are braked automatically as the gear retracts.
- NORM BRK and G in amber: normal braking is lost. Yellow brakes the wheels, with antiskid but without autobrake.
- ACCU PRESS in green: yellow pressure is available. The triple indicator now shows brake pressure.
- A green arc marks the hottest brake above 100 °C. It turns amber, with BRAKES HOT, above 300 °C.
- On ground: brake fans on, chocks rather than the parking brake, and delay takeoff until the brakes cool.
- L/G CTL in amber
- Gear position disagrees with the lever for 30 s
- N/W STEERING in amber
- Steering lost; Y shows the yellow supply
- AUTO BRK flashing
- For 10 s after autobrake disengages
- ACCU ONLY
- Alternate braking on the accumulator alone
- Memos
- AUTO BRK LO, MED or MAX; AUTO BRK OFF; BRK FAN; PARK BRK; NW STRG DISC
Gear and doors
FCOM DSC-32-10-10 P 1–6 · DSC-32-10-40 P 1–3
- Retraction
- Main gear inboard, nose gear forward
- Actuation
- Green hydraulics, sequenced electrically by two LGCIUs
- LGCIU changeover
- After each retraction cycle, or on failure
- Hydraulic cut-off
- Above 264 kt; also below 260 kt while the lever is up
- Lever interlock
- Locked DOWN with a main gear compressed or the nose wheel not centred
- Gravity extension
- Pull the crank, turn it clockwise 3 turns; the doors stay open
- The LDG GEAR indicator panel uses LGCIU 1 only; the WHEEL page uses both.
- Red UNLK: gear not locked in the selected position. Red arrow on the lever: gear not down in landing configuration.
- Move the lever in one continuous movement.
- After a training gravity extension, the system can be reset in flight if green pressure is available.
Nose wheel steering
FCOM DSC-32-20-10 P 1 · DSC-32-20-20 P 1–3 · LIM-LG P 1
- Actuator
- Yellow hydraulics, commanded by the BSCU
- Hand wheels
- 75° up to 20 kt, reducing to 0° at 80 kt
- Rudder pedals
- 6° up to 40 kt, reducing to 0° at 130 kt
- Needs
- A/SKID & N/W STRG ON, towing lever normal, an engine running, on ground
- Towing
- 95° with steering disconnected; 85° for towbarless towing
- The hand wheel button keeps pedal and autopilot orders out of steering while held.
- A cam centres the nose wheel after liftoff.
- N/W STEERING in amber: steering failure, both BSCU channels lost, yellow low pressure, or the switch OFF.
Braking modes
FCOM DSC-32-30-10 P 1–7 · DSC-32-30-20 P 1–2
| Mode | Pressure | Antiskid | Autobrake |
|---|---|---|---|
| Normal | Green, via the BSCU | Yes | Yes |
| Alternate with antiskid | Yellow, via the ABCU | Yes | No |
| Alternate without antiskid | Yellow or accumulator, via the ABCU | No, 1,000 PSI limit | No |
| Parking brake | Yellow or accumulator | – | – |
- The accumulator gives at least 7 full brake applications and holds parking pressure for at least 12 h.
- Brake pressure shows on the triple indicator only when yellow is braking.
- Antiskid works above 20 kt. It releases a wheel slowing below about 0.87 of the reference speed.
- A/SKID & N/W STRG OFF: no antiskid or steering; pedal braking, differential too, remains.
- The BSCU swaps channels at each gear lever DOWN selection.
- Brakes are carbon multidisc, and fusible plugs deflate an overheated tyre before it bursts.
Autobrake
FCOM DSC-32-30-10 P 2–5 · DSC-32-30-20 P 3
- LO
- 2 m/s², from 2 s after the ground spoilers extend
- MED
- 3 m/s², from 2 s after the ground spoilers extend
- MAX
- Takeoff: full pressure at ground spoiler extension, above 40 kt wheel speed
- Arming
- Green pressure, antiskid powered, no braking failure, one ADIRU; MAX not in flight
- Activation
- Ground spoiler extension command, with at least two SECs
- Disarming
- Pushbutton, an arming condition lost, after takeoff, or enough pedal
- DECEL comes on at 80% of the selected rate. On a slippery runway it may stay off while autobrake still works.
- A reject below 72 kt wheel speed gets no autobrake, because the ground spoilers do not extend.
- Disconnecting above 33 kt after touchdown or a reject gives the AUTO BRAKE OFF call and the AUTO BRK OFF memo.
- No braking at all: apply the LOSS OF BRAKING memory item.
Limitations
FCOM LIM-LG P 1–2 · LIM-AG-SPD P 2 · PRO-ABN-BRAKES
- VLO extension
- 250 kt / M 0.60
- VLO retraction
- 220 kt / M 0.54
- VLE
- 280 kt / M 0.67
- Tyre speed
- 195 kt ground speed
- Brakes for takeoff
- Below 300 °C with fans off, 150 °C with fans on
- Deflated tyres
- 7 kt in turns with one per gear; 3 kt with two on one main gear; steering 30°
- The brakes are not designed to hold the aircraft against high thrust; be ready to retard the thrust levers.
- Brake fans run only with the left main gear down and locked.
- BRAKES HOT in flight: if performance permits, gear down to cool, at 250 kt or less.
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Landing Gear
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Questions about A320 landing gear and brakes
Which hydraulic system operates the A320 landing gear?
Green. Two LGCIUs sequence the gear and doors electrically, and a crank allows gravity extension if green or electrical power is lost.
What are the A320 autobrake deceleration rates?
LO 2 m/s² and MED 3 m/s², both from 2 s after the ground spoilers extend. MAX is for takeoff and applies full pressure as soon as the ground spoilers extend.
How far can the A320 nose wheel be steered?
Up to 75° with the hand wheels and 6° with the rudder pedals, both reducing as ground speed rises. With steering disconnected for towing it turns up to 95°.
What happens to A320 braking when green hydraulics are lost?
Yellow takes over the brakes automatically, with antiskid and nose wheel steering still available. Autobrake is lost, and the gear can no longer be retracted.
What is the maximum brake temperature for takeoff?
300 °C with the brake fans off. With the fans on, delay takeoff until the brakes are below 150 °C.