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system:
LANDING GEAR FREE FALL
In the event of a main/auxiliary hydraulic system failure or an electrical
system malfunction, the landing gear can be extended using gravity
to allow the gear to “free fall”. Whenever free fall gear extension is to
be accomplished, the Landing Gear Control switch should be placed in
the DN position and the GEAR circuit breaker on the copilot’s circuit
breaker panel should be pulled after gear extension. This will prevent
inadvertent gear retraction in the event electrical power to the system
is regained.
Landing gear free fall extension is activated by the GEAR FREE FALL
lever located on the copilot side of the forward pedestal. Pushing this
lever mechanically unlocks the uplock actuators of the nose gear and
main gear doors. This action also actuates an emergency valve allowing
the hydraulic pressure and return lines of the door selector and gear selector
valves to connect; thus, isolating them from the main and auxiliary
hydraulic systems. Hydraulic resistance is minimized and the
landing gear “free fall” to the extended and locked position. All three
Advisory lights illuminate when gear control switches are placed in the
down position. Each gear down light illuminates as the respective gear
is down and locked. The main gear door Advisory lights will remain
illuminated since the inboard doors are still extended.
CAS Color Description
GEAR Red The landing gear is not down and locked and
other conditions indicate a landing is
imminent.
GEAR Amber • The landing gear is not down and locked
and other conditions indicate the flight is
transitioning into the landing phase.
or
• The landing gear is being operated with an
airspeed in excess of the maximum landing
gear operating speed.
Pilot’s Manual
PM-126A 3-15
NOSE WHEEL STEERING SYSTEM
The nose wheel steering system is controlled by the nose wheel steering
computer. This steer-by-wire system receives pilot and copilot inputs
through two rudder pedal position sensors and two dual pedal force
sensors. A steering command based upon pedal position and force,
nose strut position, and aircraft speed is calculated by the computer.
This command is relayed to a dc motor which positions the nose wheel
via a nose wheel strut gearbox.
The nose wheel steering system is powered by 28-vdc through the
25-amp MOTOR and 2-amp CMPTR circuit breakers located on the pilot’s
circuit breaker panel (GEAR/HYDRAULICS group [NOSE
STEER]). Arming of the system is initiated by depressing the momentary-
action NOSE STEER switch (GEAR/HYD panel). The NOSE
STEER switch will illuminate ON when the following conditions occur:
- Both system dc power sources are on and available to the computer.
- The nose gear is down and locked.
- No system faults or failures are detected.
- Main gear and nose gear weight-on-wheels switches are in the ground
mode.
Once the system is armed, computer steering commands will be transmitted
to the nose wheel during ground operation.
For low speed ground operations, 60° of steering authority either side
of center is available. At low speed and large rudder pedal deflection,
the nose wheel displacement will be large for high maneuverability.
Once a rudder pedal has reached its stop, further nose wheel displacement
is generated by additional force being applied to that rudder pedal.
As ground speed increases, the maximum wheel deflection is
reduced to zero. The nose wheel steering system remains active
through liftoff.
The NOSE STEER switch will illuminate ON when the system is
armed. When the nose gear is no longer in the down and locked position,
the ON annunciator on the NOSE STEER switch will extinguish;
however, the computer is still powered and system monitor circuitry
remains active.
For landing, the nose wheel steering system becomes active only after
all weight-on-wheels switches are in the ground mode. The ON annunciator
on the NOSE STEER switch will illuminate provided no faults
have been detected. The nose wheel steering system has a fade-in feature
that allows several seconds to transition from rudder steering to
nose wheel steering, to avoid an initial oversteer condition.
The nose wheel steering system can be disarmed at anytime by depressing
the NOSE STEER switch, or either Control Wheel Master
(MSW) switch during ground operations.
Pilot’s Manual
3-16 PM-126A
NOSE STEER SWITCH
The NOSE STEER switch is used to activate nose steering circuits for
taxi operations. Momentarily depressing the NOSE STEER switch will
　
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