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Chapter 8. Landing gear

Table of Contents

8.1. Loss of braking (memory item)
8.2. Residual braking procedure
8.3. Gravity extension
8.4. Asymmetric braking
8.5. Landing with abnormal landing gear
8.6. Flight with landing gear extended
8.7. Gear shock absorber fault
8.8. Gear not uplocked
8.9. Gear not downlocked
8.10. Gear doors not closed
8.11. Uplock fault
8.12. LGCIU disagreement
8.13. LGCIU fault
8.14. Gear not down
8.15. Park brake on
8.16. Nosewheel steering fault
8.17. Antiskid nosewheel steering off
8.18. Antiskid nosewheel steering fault
8.19. Brake system fault
8.20. Brakes hot
8.21. Auto brake fault
8.22. Hydraulic selector valve fault
8.23. Failure of normal braking system
8.24. Failure of alternate braking system
8.25. Failure of normal and alternate braking systems
8.26. Brake accumulator low pressure
8.27. Released brakes, normal system
8.28. Released brakes, alternate system
8.29. Brake temperature limitations requiring maintenance action

8.1. Loss of braking (memory item)

If it is simply an autobrake failure, just brake manually. Otherwise, apply max reverse and attempt to use the alternate brake system. To do this, release the brake pedals and turn off the ASKID & NW STRG switch. If the alternate system also appears to have failed, short successive applications of the parking brake may be used. Use of the parking brake in this way risks tire burst and lateral control difficulties (due brake onset asymmetry) so delay until low speed if at all possible.

[FCOM PRO.AEP.BRAKES]

8.2. Residual braking procedure

Residual brake pressure must be checked after landing gear extension as there is no ECAM warning. A brief brake pressure indication is expected as the alternate system self tests after the gear is down locked, but pressure should quickly return to zero. If the triple indicator shows residual pressure after this test, try to zero it by pressing the brake pedals several times. If a landing must be made with residual pressure in the alternate braking system, use autobrake MED or immediate manual braking to prioritise the normal system. Anticipate brake asymmetry at touchdown.

[QRH AEP.BRAKES, FCOM PRO.AEP.BRAKES]

8.3. Gravity extension

Gravity extension is achieved by turning the GRAVITY GEAR EXTN handcrank clockwise three times until a mechanical stop is reached. Once the gear is down, the LG lever should be set to down to extinguish the UNLK lights and remove the LG CTL message from the WHEEL page.

Availability of landing gear indications depends on the nature of the failure that resulted in the requirement for gravity extension. LDG GEAR control panel indications may still be available if LGCIU 1 is otherwise unserviceable, providing that it is electrically supplied.

Gear doors may show amber on the WHEEL page after gravity extension. There may also be spurious LGCIU 2 FAULT or BRAKES SYS 1(2) FAULT ECAM warnings.

[QRH AEP.L/G, FCOM PRO.AEP.L/G]

8.4. Asymmetric braking

Defined as all brakes on one gear released (indicated by amber brake release indicators on both wheels of one main gear on the WHEEL SD page). When the remaining brakes are applied, the aircraft will tend to swing towards them. This tendency must be countered with rudder, hence the braking must be progressive and co-ordinated with available rudder authority. Crosswinds from the side of the available brakes will re-inforce the swing, so anything greater than 10kt from that side should be avoided.

If a reverser is inoperative on the same side as the inoperative brakes, do not use the remaining reverser since it would also re-inforce the swing.

Landing distances will increase significantly.

[QRH AEP.BRAKES, FCOM PRO.AEP.BRAKES]

8.5. Landing with abnormal landing gear

A landing should be carried out on a hard surface runway using any available landing gear. Foaming of the runway is recommended. Manual braking should be used. Reverse thrust should not be used as it will cause ground spoiler extension. The GRVTY GEAR EXTN handcrank should be turned back to normal to allow the landing gear down actuators to be pressurised and thus reduce the chance of gear collapse.

If the nose gear is not available, move the CG aft by moving passengers to the rear of the aircraft. Use elevator to keep the nose off the runway, but lower the nose onto the runway before elevator control is lost. Braking must be progressive and balanced against available elevator authority. The engines should be shut down with the ENG MASTER switches prior to nose impact.

If one main gear is not available, consider crossfeeding to remove the fuel from the wing with the unserviceable gear. The anti-skid system cannot operate with a single main gear extended and must be switched off to avoid permanent brake release. The ground spoilers should not be armed in order to maintain the maximum possible roll authority. The engines should be shut down at touchdown. After touchdown, use roll control to keep the unsupported wing from touching down for as long as possible.

If both main gear are unavailable, the engines should be shut down in the flare. Pitch attitude at touchdown must be >6°.

All doors and slides are available for evacuation in any of the normal gear up attitudes.

[QRH AEP.L/G, FCOM PRO.AEP.L/G]

8.6. Flight with landing gear extended

Flight into expected icing conditions is not approved. Gear down ditching has not been demonstrated. FMGC predictions will be erroneous – selected speed should be used for all phases except approach. CLB and DES modes should not be used. Altitude alerting will not be available. Any failure that normally causes a degradation to alternate law will instead cause a degradation to direct law.

The dual engine failure scenario is modified to reflect the gear limiting speed. Assisted start should be preferred. If the APU is not available, gear limit speeds should be disregarded to achieve a windmill start. Flight controls will be in direct law; manual pitch trim should be available, even when not annunciated on the PFD.

Performance in all phases will be affected. In particular, approach climb limiting weights for go-around (see FCOM PRO.NOR.SUP.L/G) must be reduced by 14%. Fuel burn will increase (approximate factor is 2.3). Engine out ceiling and take-off performance are also impacted.

[FCOM PRO.NOR.SUP.L/G]

8.7. Gear shock absorber fault

A shock absorber did not extend when airborne or did not compress on landing. If airborne the gear cannot be retracted. Respect the gear extended limit speed of 280kt and see Section 8.6, “Flight with landing gear extended”.

[L/G SHOCK ABSORBER FAULT, FCOM PRO.AEP.L/G]

8.8. Gear not uplocked

Landing gear retraction sequence has not completed within 30 seconds. If the gear doors have closed, the gear will rest on the doors so avoid excess g loads. If the doors have not closed, recycle the gear. If this does not work, select the gear down and see Section 8.6, “Flight with landing gear extended”.

[L/G GEAR NOT UPLOCKED, FCOM PRO.AEP.L/G]

8.9. Gear not downlocked

If the landing gear extension sequence has not completed within 30 seconds, retract the gear, wait until it has fully stowed, and then redeploy it. Recent studies show that if the gear does not immediately deploy successfully following reselection, it may deploy normally within the next two minutes as hydraulic pressure continues to act on the gear and doors throughout this time. If still unsuccessful after two minutes, attempt to deploy the gear by gravity (see Section 8.3, “Gravity extension”).

[L/G GEAR NOT DOWNLOCKED, FCOM PRO.AEP.L/G]

8.10. Gear doors not closed

A gear door is not uplocked. Recycle the gear. If the doors cannot be closed, speed is limited to 250kt/M0.6.

[L/G DOORS NOT CLOSED, FCOM PRO.AEP.L/G]

8.11. Uplock fault

An uplock is engaged when the corresponding gear is downlocked. As the uplock will not move to accept the gear the gear must be left down. See Section 8.6, “Flight with landing gear extended”.

[L/G GEAR UPLOCK FAULT, FCOM PRO.AEP.L/G]

8.12. LGCIU disagreement

The LGCIUs disagree on the position of the gear. In the absence of other ECAM warnings, the gear position can be assumed to agree with the gear lever position.

[L/G SYS DISAGREE, FCOM PRO.AEP.L/G]

8.13. LGCIU fault

The FADECs use LGCIU input to determine idle mode. If a LGCIU is determined to be faulty, the system failsafes to approach idle mode, and modulated idle and reverse idle (and hence reversers) will not be available.

The GPWS uses LGCIU 1 to determine landing gear position. If this LGCIU is faulty, the GPWS will need to be inhibited to prevent spurious warnings.

If both LGCIUs are lost, normal landing gear control and indicating systems are lost. The gear must be gravity extended (see Section 8.3, “Gravity extension”). Additionally, the autopilots and autothrust are lost (normal law remains available) and wing anti-ice is limited to 30s of heating (i.e. the ground test), the only indication of which is a “no Anti-Ice” message on the BLEED SD page.

[L/G LGCIU 1(2) FAULT, FCOM PRO.AEP.L/G]

8.14. Gear not down

Indicates that the landing gear is not downlocked when radio altitude is below 750ft rad alt and N1 and flap setting indicate that the aircraft is on approach. If rad alt data is not available, it indicates gear is not down when flap 3 or flap full is selected. In some cases the warning may be cancelled with the emergency cancel pushbutton.

[L/G GEAR NOT DOWN, FCOM PRO.AEP.L/G]

8.15. Park brake on

The parking brake is set when the thrust levers are set to FLX or TOGA. Check the position of the brake handle position and for pressure indications on the brake triple gauge.

[CONFIG PARK BRK ON, FCOM PRO.AEP.CONFIG]

8.16. Nosewheel steering fault

Nosewheel steering is unavailable so differential braking must be used to steer the aircraft. The nosewheel may not be aligned if the L/G shock absorber ECAM is also displayed, in which case delay nosewheel touch down as long as possible. Cat III dual will not be available.

[WHEEL N/W STRG FAULT, FCOM PRO.AEP.WHEEL]

8.17. Antiskid nosewheel steering off

The A/SKID & NW STRG switch is off. The ABCU controls braking through the alternate braking system. Antiskid is not available so landing distance will increase significantly. Autobrake and nosewheel steering will also not be available.

[BRAKES ANTI SKID/NWS OFF, FCOM PRO.AEP.BRAKES]

8.18. Antiskid nosewheel steering fault

Either:

  • both BSCU channels have failed or

  • the normal brake system has been lost and the yellow hydraulic pressure is low.

Effects are as for Section 8.17, “Antiskid nosewheel steering off”, although if yellow hydraulic pressure is low braking will be accumulator only.

[BRAKES A/SKID NWS FAULT, FCOM PRO.AEP.BRAKES]

8.19. Brake system fault

A fault has been detected in one channel of the BSCU. Loss of redundancy only.

[BRAKES SYS 1(2) FAULT, FCOM PRO.AEP.BRAKES]

8.20. Brakes hot

At least one brake temperature is >300°C. Check Section 8.29, “Brake temperature limitations requiring maintenance action” if the temperature is excessive or the brake temperatures are not reasonably even.

Temperature must be <300°C for takeoff to prevent ignition of any hydraulic fluid that leaks onto the brake. Use brake fans as necessary to bring the temperature down in time for the next takeoff. The brake fans also cool the temperature sensor, so assume the real brake temperature is twice that indicated if they have recently been used.

If the warning appears in flight, providing that performance permits, the landing gear should be extended to allow the brakes to cool.

[BRAKES HOT, FCOM PRO.AEP.BRAKES]

8.21. Auto brake fault

A failure was detected when the autobrake was armed. Brake manually.

[BRAKES AUTO BRK FAULT, FCOM PRO.AEP.BRAKES]

8.22. Hydraulic selector valve fault

This ECAM message may indicate two completely different conditions:

  1. The normal brake selector valve has failed in the open position. The normal servo valves (downstream of the selector valve) will have continuous full pressure at their inlets, but, as long as anti-skid is operative, will control brake pressure and anti-skid normally.

  2. The steering selector valve has failed in the open position. This means that the steering will remain pressurised as long as there is pressure in the yellow hydraulic system. This has obvious implications if towing is attempted, but will also mean that the nosewheel will go to maximum deflection if the A/SKID & N/W STRG switch is selected off or the BSCU is reset.

[WHEEL HYD SEL FAULT, FCOM PRO.ABN.32]

8.23. Failure of normal braking system

Normal braking is lost, but alternate braking and anti-skid are available. Landing distance increases slightly.

[BRAKES NORM BRK FAULT, FCOM PRO.AEP.BRAKES]

8.24. Failure of alternate braking system

Loss of redundancy only.

[BRAKES ALTN BRK FAULT, FCOM PRO.AEP.BRAKES]

8.25. Failure of normal and alternate braking systems

The only braking remaining is the parking brake. See Section 8.1, “Loss of braking (memory item) for method.

[BRAKES NORM + ALTN FAULT, FCOM PRO.AEP.BRAKES]

8.26. Brake accumulator low pressure

Braking is not available unless either the green or yellow hydraulic systems are pressurised. If the engines are shut down, attempt to recharge the accumulator using the yellow system electrical pump. When parking the aircraft, use chocks.

[BRAKES BRK Y ACCU LO PR, FCOM PRO.AEP.BRAKES]

8.27. Released brakes, normal system

If normal braking is active and at least one engine is running, the BSCU self tests when it receives a “gear downlocked” signal from either of the LGCIUs. The BRAKES RELEASED ECAM is provided if at least one set of brakes on a main wheel is incorrectly released during this test. The failed brake is shown by an amber release symbol on the WHEEL page. Loss of a brake leads to increased landing distances. If both brakes on the same gear are released, see Section 8.4, “Asymmetric braking”.

[BRAKES RELEASED, FCOM PRO.AEP.BRAKES]

8.28. Released brakes, alternate system

The ABCU self tests the brakes in a similar manner to the BSCU (see Section 8.27, “Released brakes, normal system”). If this test is failed, normal braking can be expected as long as the normal braking system is active. If the alternate braking system is active, braking will be asymmetric (see Section 8.4, “Asymmetric braking”) because released brakes occur in pairs with the alternate braking system.

[BRAKES ALTN L(R) RELEASED, FCOM PRO.AEP.BRAKES]

8.29. Brake temperature limitations requiring maintenance action

Maintenance is required if:

  • One brake temp is >600°C and the other brake on the same gear is 150°C less

  • One brake temp is <60°C and the other brake on the same gear is 150°C more

  • The average temp of one gear is 200°C more than the average temp of the other

  • Any brake temp exceeds 900°C

  • A fuse plug has melted

[EOMB 2.3.21]