OPERATIONS MANUAL

Landing Gear
System Overview:
Gear steering
The landing gear consists of 2 body gear, 2 wing gear, and 1 nose gear.
The body gear and the nose gear are steerable. The steering mechanism is
powered by hydraulic system 1. The flight deck provides a steering tiller for
the captain and one for the first officer. When the tiller is fully rotated to
the left or right, the nose gear is turned by 70° into the respective direction.
The body gear turns out of its center position when the nose gear turn
angle exceeds 20°, and when the wheel speed is below approximately 18 kt.
Otherwise, the body gear is centered. It is also centered when the IRS is
aligned and the IRS computed groundspeed is above circa 45 kt, or when
the air-ground logic is in air mode. When the body gear turns, it turns
opposite to the nose gear direction; this is because the body gear is located
aft of the aircraft’s center axis. Body gear steering reduces the turning radius
of the aircraft.—The nose gear can also be turned by the rudder pedals up
to 7° in either direction.
Wheel brakes
The pilots’ brake pedals allow symmetric and asymmetric braking of the
wing and body gear. There are no brakes on the nose gear. The normal
brake system is powered by hydraulic system 4. If this fails, the alternate
brake system activates. The alternate brake system is powered by hydraulic
system 1; or, if that fails, by hydraulic system 2.—Autobrakes may be
armed with a preselected, fixed groundspeed deceleration for the landing
rollout; or may be armed for a rejected takeoff which will aim at maximum
deceleration.—A parking brake lever can be used to lock the brake pedals
in the fully depressed positions. (In the simulator, the brakes can be promptly
cooled by the Cool brakes button on Instructor > Situation > Service.)
Antiskid
The antiskid system operates during autobrake activity as well as during
manual braking. It detects skidding by comparing the wheel speeds with the
IRS computed groundspeed. When skidding is detected, the brake pressure
on the affected wheels is automatically reduced.
Brake torque limiters
Each wheel is fitted with a brake torque sensor. When an excessive torque
is detected, the brake pressure is reduced in order to prevent structural
damage.
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