Learjet 60 - Landing Gear Selector Switch

Learjet 60
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Pilot's Manual
LANDING GEAR SELECTOR
SWITCH
The LANDING GEAR switch, located
on the center instrument panel,
is a lever-lock type switch and must be
pulled aft before selecting the
UP
or DN position . The switch controls
the position of the gear selec-
tor valve and the door selector valve through gear
and door position
switches .
Electrical power for the control circuits is 28
VDC supplied
through
the 2-amp GEAR circuit breaker on the
copilot's circuit
breaker panel . The
landing gear control circuits are operative
during
EMER BUSmode .
Landing gear
retraction cycle : When the LANDING
GEAR switch is
placed in the UP position and
the squat switches are in
the air mode,
the following sequence of events
will occur :
1 . 28 VDC will be applied
to the "open" solenoid
of the door selec-
tor valve and
hydraulic pressure will be
applied to both inboard
main gear door uplock
actuators and door actuators .
2 . When the inboard main
gear doors open, door
open switches
will complete a circuit
from the LANDING
GEAR switch to the
"up" solenoid
of the gear selector valve .
Hydraulic pressure will
be applied to
the main and nose gear
actuators and the gear will
retract .
3 . When the main gear
retract, gear up
switches will complete a
circuit from the
LANDING GEAR switch to
the "close" solenoid
of the door
selector valve . Hydraulic
pressure will be
applied to
the
inboard main gear doors actuators
to raise the gear
doors .
Additionally, a gear down safety
switch will complete a
circuit
to the "up"
solenoid of the gear
selector valve to
maintain con-
tinuous
hydraulic pressure in the
gear actuators .
4 .
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The
gear doors are latched by
uplatch actuator
spring tension .
PM-123
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3-7
Original