Wheel orientation
Until the Airbus A380, the front wheels steered the aircraft on the ground. Given its weight and size, the A380 is also equipped with a wheel orientation system for the two rear wheels of each of the two central bogies situated under the fuselage.
The steering system has a twofold function:
Direct the aircraft on the ground: within a sector of +/- 60 degrees for a commercial aircraft and up to +/- 180 degrees for the onboard naval version in a combat aircraft
Attenuate the impact affecting the landing gear during taxiing
The system is of the hydraulic type, using servo controls. It also includes:
An actuator (a rack or two push-pull actuators)
A pressure sensor measuring the wheel orientation angle (to within accuracy of +/-0.5 degrees)
A computer
A shimming damper
The computer handles three primary functions:
in the servo-control group, it compares the pilot’s order with the real position of the wheels at the same moment and calculates the new order, which is in fact transmitted to the servo-control.
It constantly monitors its own correct operation, as well as that of the sensor and the servo-control, by a process known as automonitoring
It assists maintenance by supplying information about any failures it has detected.
