Airbus A220 - Landing gear
The door mechanism is hinged to the aircraft structure and attached to the main landing gear. The wheels are covered when retracted.
The door mechanism is hinged to the aircraft structure and attached to the main landing gear. The wheels are NOT covered when retracted. In the fully retracted position, the main wheel tires remain partially exposed at the tire circumference.
The normal extension and retraction of the landing gear is controlled by the Landing Gear and Steering Control Units (LGSCUs). The alternate extension allows free-fall extension of the landing gear if normal extension fails.
The parking brakes can also be applied by the ground crew from the electrical/towing service panel with the PARK BRK guarded switch, which is powered by the DC EMER BUS.
The PARK BRAKE switch on the parking brake panel in the flight deck has priority over the PARK BRK switch on the external electrical/towing service panel. If any of the battery switches (BATT 1 or BATT 2) on the ELECTRICAL panel are selected to AUTO, the electrical/towing service panel PARK BRK switch is inhibited and the parking brakes are set to the flight deck PARK BRAKE switch position.
Towbarless towing permits the ground crew to configure and tow the aircraft without the need to access the flight compartment. When the TOW PWR switch, on the electrical/towing service panel, is selected ON, electrical power from the _____ is used to apply or release the parking brake when the PARK BRK switch is selected to the required position.
The steering tiller turns the nosewheel up to _____ either side of center, and is intended for low speed taxi and maneuvering in the ramp area. The steering tiller is automatically centered by a spring and its movement is damped to avoid overtravel and to be more representative of nose wheel motion.
If there is malfunction of the normal braking system, an alternate brake mode is available with the use of the ALTN BRAKE guarded switch on the landing gear panel. This mode provides direct, proportional control from the toe brakes on the rudder pedals to the EMAs on the wheels. Braking system protections remain available.
There are no braking system protections available when the alternate brake mode is activated. When the alternate brake mode is selected, the ON light on the switch comes on and the status message ALTN BRAKE ON is displayed on the EICAS page
The Landing Gear and Steering Control Unit (LGSCU) commands and monitors the steer-by-wire steering system. It receives the input from the rudder pedals or tiller to command the steering control valve. The steering control valve supplies hydraulic pressure from _____ to the steering motor, which drives a rack and pinion gear to turn the nose landing gear.
Position sensors, installed on the nose landing gear main fitting, supply steering angle feedback to the LGSCUs.
A tire pressure indicating system is installed to monitor and transmit tire pressure information to the STATUS synoptic page. There are three fusible plugs installed on the brake side of each main wheel to release tire pressure when the wheel temperature exceeds approximately _____.
At the next extension after each _____, the LGSCU does an alternate extension instead of a normal extension. This is to test the alternate extension circuitry to detect abnormal conditions.
While the test is in progress, an ALTN GEAR DN advisory message is displayed on the EICAS page. When the landing gear is down and locked, the LGSCU reverts to normal operation by pressurizing the landing gear extension actuators, and the advisory message is removed.
In the event of a nosewheel steering system failure, the nosewheel is capable of castering.
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The ALTN GEAR (alternate gear) guarded switch, on the landing gear panel, is used to _____ release the landing gear uplocks, which allows the gear to free-fall.
Turning with both steering tillers simultaneously, the LGSCU algebraically combines the commands to a maximum of _____ either side of center. The turning angle is also limited by ground speed.
When a turn is executed with the steering tiller and rudder pedals at the same time in the same direction, the LGSCU algebraically adds the two commands. This results in an increased angle for the turn up to the maximum of 80 degrees.
The Nose Landing Gear (NLG) retracts rearward. It is connected to the door linkage assembly that drives the four NLG doors to close when the NLG is fully retracted.
The Nose Landing Gear (NLG) retracts forward. The nosewheel tires are completely protected by four NLG doors.
What is the meaning of this landing gear position indication on the EICAS page?
On ground, the automatic braking system will only allow RTO to be selected. In flight, only the selection of LO, MED and HI are possible.
The automatic braking system is deactivated when:
If a takeoff is rejected at a ground speed of less than _____, manual braking is necessary to stop the aircraft, regardless of the AUTOBRAKE switch position.
When _____, the LGSCU inhibits gear retraction.
When the ground speed greater than 100 kt, there is maximum reduction of nosewheel steering. The steering tiller control of the nosewheel is limited to _____ either side of center.
When the PARK BRAKE switch is selected ON (pulled and turned), the aircraft electric brakes lock in the braked position. An internal mechanism in the actuator will keep the brakes in the locked position without electrical power. The parking brake can be applied and removed when the aircraft is powered by:
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What is the meaning of this landing gear position indication on the EICAS page?
The brake control system has an anti-skid system and wear indication. The Brake Temperature Monitoring System (BTMS) is provided via the avionics system from input from the Brake Control System (BCS) and Brake Temperature Sensor (BTS). Wear data is only shown when there is less than _____ of brake life remaining (equivalent to less than 100 landings).
The PEDAL DISC (Disconnect) switch, on the steering tiller, disconnects the rudder pedals from the steering system so that ground rudder checks can be done without steering the nosewheel. The amber PEDAL STEER DISC caution message is displayed on the EICAS page.
Only the PEDAL STEER DISC status message is displayed on the EICAS page.
Locked wheel protection - The locked wheel protection releases the respective brake of a locked wheel when detected. When taxiing, to avoid braking command release during turning maneuvers, the locked wheel protection is inhibited when wheel speeds are less than _____.
The landing gear system has two main landing gear assemblies and one nose landing gear assembly. Each assembly is equipped with two tires. The landing gear is extended and retracted by hydraulic actuators and pressure from:
What is the meaning of this landing gear position indication on the EICAS page?
The autobrake system decreases the life cycle of the carbon brakes.
The autobrake system has been shown to significantly reduce the number of brake applications necessary to slow the aircraft. The autobrake system also increases the life cycle of the carbon brakes.
The anti-skid protection provides variable wheel speed control to prevent deep skid at each individual brake to minimize stopping distance. Anti-skid is available at more than _____.
If the wheel speed is more than 204 knots, the BCS will consider the wheel speed at 204 knots. It is deactivated when wheel speeds are less than 10 knots.
The parking brake system can be used to stop the aircraft when the normal and alternate braking systems have failed on ground. If the parking brake is activated in flight, the parking brake is failed until the system is powered again on ground. There are no braking system protections available when the parking brake is used for deceleration.
The NOSE STEER switch on the landing gear panel disengages the nosewheel steering system for towing and ground safety. This allows a larger towing turn radius of up to _____ either side of center, without disconnecting the torque links.
When the NOSE STEER switch is selected, the OFF label is illuminated white and the status message NOSE STEER OFF is displayed on the EICAS page.
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The rudder pedals provide fine-angle inputs for the nosewheel steering control system. The rudder pedals command a deflection up to _____ either side of the center of the nosewheel steering.
The caution message 'PARK BRAKE FAIL' is displayed on the EICAS page if:
If an uncommanded parking force greater than 200 lb is detected, the caution message 'BRAKE ON' is displayed on the EICAS page.