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pedal deflection the nose wheel displacement will be large for high
maneuverability. Once a rudder pedal hasreached its stop, further nose
wheel displacement is generated by additional force being applied to
that rudder pedal. As ground speed increases, the maximumwheel deflection
is reduced to zero. At 90 knots 28 VDC is removed and the system
disengages. Above 90 knots the nose wheel is allowed to castor.
Nose wheel steering engage circuits are controlled through the momentary-
action pedestal-mounted ARM/NOSE STEER switch and the
Control Wheel Master Switches (MSW). When the squat switches are in
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Learjet 31A
Pilot's Manual
the ground mode, depressing and releasing the ARM/NOSE STEER
switch will activate the computer when AC and DC power are available,
the nose gear is down and locked, and no faults are detected by
the system monitor. When the system is active the STEERON annunciator
on the glareshield and the ARM annunciator on the ARM/NOSE
STEERswitch will illuminate. At 90 knots, when the system disengages,
the glareshield STEER ON annunciator will extinguish . When the
nose gear is no longer in the down and locked position, the ARM annunciator
on theARM/NOSESTEER switch will extinguish, however;
the computer is still powered and system monitor circuitry remains active.
When the nose gear is down and locked for landing the ARM annunciator
on the ARM/NOSE STEER switch will illuminate provided
no faults have been detected. After touchdown, when ground speed
decreases to 90 knots, the STEERON light on the glareshield will illuminate
and steering authority will increase as ground speed decreases.
If the system cannot be armed, limited authority steering (18° either
side of neutral) is available by depressing and holding either MSW It
should be noted that in some instances, even though a fault has been
detected, the system will continue to function normally until shutdown.
After that, however, it will not be possible to operate the system
with full steering authority until the fault hasbeen corrected. If the system
cannot be accessed by either MSW, sufficient control is still available
by differential braking.
The nose wheel steering system is powered by 28 VDC supplied
through the 20-amp NOSE STEER circuit breaker and 115 VAC supplied
through the 2-ampNOSE STEERcircuit breaker in the TRIM-FLT
CONT group on the pilot's circuit breaker panel.
STEER ON LIGHT
The green STEERON light on the glareshield annunciator panel illuminates
to indicate the nose wheel steering system is capable of responding
to rudder pedal inputs .
ARM/NOSE STEER SWITCH
Normally, theARM/NOSE STEERswitch is used to activate nose steering
circuits for taxi operations . Momentarily depressing the ARM/
NOSE STEERswitch will activate the system and theARMannunciator
will illuminate. When nose steering has been activated, the system can
be disengaged by depressing then releasing either the pilot's or copilot's
Control Wheel Master Switch (MSW) or by depressing theARM/
NOSE STEERswitch a second time. The disconnect tone will sound.
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Learjet 31A
CONTROLWHEEL MASTER SWITCH -NOSE STEERING FUNCTION
Depressing and holding either Control Wheel Master Switch (MSW)
will engage the nose wheel steering system . While the MSWis held, the
nose steering system will operate normally and the STEERON annunciator
will be illuminated. When the MSW is released, the nose wheel
steering system will disconnect. TheSTEERON annunciator will extinguish.
In the event that nose wheel steering will not arm, theMSWcan
be depressed and held for limited authority steering, under some fault
conditions .
WHEEL BRAKE SYSTEM
The primary brake system utilizes hydraulic system pressure forpower
boost. Hydraulic pressure from the nose gear down line is metered to
the disc-type wheel brakes by the power brake valves . The valves are
controlled by the rudder pedal toe brakes through mechanical linkage.
Twoshuttle valves in the pressure lines preventfluid feedbackbetween
the pilot's and copilot's pedals . Four additional shuttle valves connect
the pneumatic system to the brake system for emergency braking. Hydraulic
fuses, located in themain gear wheel wells, will close toprevent
pressure loss if fluid flow exceeds normal brake actuation rate. "Snubbing"
of the main gear wheels is accomplished during retraction by
means ofhydraulic back pressure in the brake lines caused by a restrictor
in the return line. An integral anti-skid system is installed to effect
maximumbraking efficiency. When parking, it is advisable to have the
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