ATA 32 - LANDING GEAR

• Landing Gear Control and Interface Units (LGCIU) 1 and 2 electrically control gear and door sequencing.

• Each LGCIU in turn controls a complete gear cycle: one UP selection and one DOWN selection.

• Normal braking is obtained when:

1) The green hydraulic pressure is available,

2) The Anti/SKID and Nose/Wheel Steering control switch is in the

ON position,

3) The Parking Brake control switch is in the OFF position.

• Putting ON the parking brake, deactivates the other braking modes and the A/SKID system.

• (CLASSIC) The selection from normal to alternate braking is made by the automatic selector. This gives the priority to the Green Hydraulic System when both Green and Yellow are pressurized.

• (CLASSIC) The alternate braking is controlled by the auxiliary low-pressure system linked to the brake pedals and the dual valve modulates the brake pressure. (ENHANCED) No low-pressure system, alternate braking is controlled by ABCU

(Alternate Braking Control Unit)

• LANDING GEAR WHEELS AND DOORS EXT/RETR. (LGCIU)

- ENHANCED: GREEN HYD SYS

- CLASSIC: GREEN HYD SYS

Both LGCIUs failure and/or loss of Green hyd sys → Free Fall Extension (3 clockwise

turns of manual extension handle)

• BRAKING SYSTEM (BSCU)

- ENHANCED: YELLOW HYD SYS

- CLASSIC: GREEN HYD SYS has priority over Yellow hyd sys (Automatic selection Valve)

• ALTERNATE BRAKING SYSTEM / PARKING BRAKE (ABCU)

- ENHANCED: YELLOW HYD SYS or BRAKE ACCUMULATOR

- CLASSIC: YELLOW HYD SYS or BRAKE ACCUMULATOR

• STEERING SYSTEM (BSCU)

- ENHANCED: YELLOW HYD SYSTEM

- CLASSIC: GREEN HYD SYSTEM

• The steering system is controlled by the BSCU (Braking and Steering Control Unit).

• Landing Gear Lever UP: LGCIU swap.

• Landing Gear Lever DOWN: BSCU swap.

• Alternate Braking Accumulator (powered by Yellow hyd sys) when fully charged can provide 7 braking actions and/or last full charged for 12 hours.

• The brake pedal XMTR units transform the mechanical input from the right and left pedals into electrical signals which are sent to the Braking and Steering Control Unit (BSCU) in normal braking and to the Alternate Braking Control Unit (ABCU) in alternate braking.

• The steering system uses the yellow hydraulic system (ENHANCED) to operate a steering actuating cylinder, which changes the direction of the NLG wheels. (CLASSIC is on green sys), pedals 6 degrees, tillers 75 degrees,

The maximum towing angle is 95 degrees on each side.

• With an LGCIU 1 fault, the indications on the LDG GEAR indicator panel are inoperative.

• When the airspeed is greater than 260 (+ or - 5) kts the hydraulic circuit to the L/G is depressurized. (airspeed comes from ADIRU 1 and 3).

• The lever is locked in the "DOWN" position by an interlock mechanism as soon as either Landing Gear Control and Interface Unit (LGCIU) detects any shock absorber not extended or nose wheels not centered.

• The auto brake system is armed if one of the three modes P/B (LO, MED or MAX) is pressed in and the following conditions are met: GREEN available, BSCU elec powered, no failure.

• The Braking and Steering Control Unit (BSCU) gives anti-skid control during normal and alternate braking by either system 1 or 2 of the BSCU.

• If the two BSCU systems are supplied simultaneously system 1 has priority and system 2 is in standby. System on standby will take control when L/G control lever is placed in “lever down” position.