Landing Gear

During normal operation, the landing gear is electrically controlled and hydraulically operated. Proximity sensors provide status to the MAUs. Hydraulic systems 1 and 2 are required. The SPDA controls the landing gear lever. The landing gear has these properties:

Steering up to 76°
Carbon brakes

Main gear assembly

2 wheels with brakes attached to a telescopic shock strut
folding side stay (holds gear extended)
locking stay (holds the side stay extended)
proximity sensors
hydraulic release actuator (unlocks locking stay on retraction)
hydraulic retraction actuator (retracts gear)
uplock (holds landing retracted)
gear doors (mechanically operated)

Nose gear assembly

2 wheels with hydraulic steering actuator attached to a telescopic shock strut
folding drag brace (holds gear extended)
locking stay (holds drag brace extended)
2 downlock springs (hold locking stay extended)
proximity sensors and feedback sensors (feedback to the NWSCM)
hydraulic release actuator (unlocks locking stay on retraction)
hydraulic retraction actuator (retracts gear)
uplock (holds landing retracted)
gear doors (mechanically operated)

Normal gear operation

The gear lever sends a signal through the PSEM to the landing gear selector valve.

Electrical override mode

The gear lever takes direct control of the landing gear selector valve, removing the PSEM from the loop. This should be used if there is a PSEM failure.

Alternate gear extension

The alternate gear extension system is used if there is a hydraulic or electrical failure. In this case extension is mechanically controlled and gravity powered. Uplocks are all mechanically released.