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tuators incorporate integral downlocking de-
vices and no downlock pins are required. Gear
position indicators are displayed on the cen-
ter instrument panel.
Primary gear extension is via the engine-driven
hydraulic pumps. Should those fail, the gear
can be extended by mechanically unlocking the
nose and main gear door uplock mechanisms
and allowing the landing gear to free-fall into
place. The landing gear can also be lowered
with the auxiliary hydraulic system if the main
hydraulic system fails, but free-fall should be
attempted first to preserve auxiliary hydraulic
fluid for flap and brake operation.
Brake input command to the brake-by-wire
system is controlled by four dual transducers
linked to the pilot and copilot rudder pedals.
Hydraulic pressure is then controlled by the
Brake Control Unit (BCU) to provide pressure
to the multiple disc brake assemblies in pro-
portion to pedal deflection. Additional features
of the brake system include touchdown pro-
tection logic that allows wheel spinup prior to
braking application, individual locked wheel
protection, and gear retraction braking.
The anti-skid function provides maximum
braking without wheel skid. With the anti-
skid function selected, wheel speed trans-
ducers supply electrical signals to the BCUs
which control the individual control valves
that modulate braking pressure. A brake ac-
cumulator and auxiliary hydraulic pump are
installed for parking brake and emergency
brake pressure. The parking brake is set with
a handle located on the center pedestal. The
same parking brake handle (system) also pro-
vides emergency braking in the event of mul-
tiple hydraulic/electrical failures and supplies
at least six emergency brake applications.
A variable-authority, digital nosewheel steer-
ing system is installed. When the system is en-
gaged, rudder pedal input signals provide
steering authority of up to 60 degrees of de-
flection at slow speeds, decreasing at the
higher taxi/takeoff and landing speeds, as de-
termined by main gear wheel speed transducer
signals.
L E A R J E T 4 5
P I L O T T R A I N I N G M A N U A L
14-2
FOR TRAINING PURPOSES ONLY
L E A R J E T 4 5
P I L O T T R A I N I N G M A N U A L
FlightSafety
international
FlightSafety
international
DOWN
DOWN
DOWN
N
L
R
ON
ON
ON
OFF
GEAR / HYD
NOSE STEER
ANTI-SKID
AUX HYD
HYD XFLOW
VLO
200
VLE
260
UP
DN
DOWN
DOWN
DOWN
N
L
R
ON
ON
ON
OFF
GEAR / HYD
NOSE STEER
ANTI-SKID
AUX HYD
HYD XFLOW
VLO
200
VLE
260
UP
DN
Figure 14-1. Gear/Hydraulic Control Panel