Learjet 60 - HYD PRESS Indicator; HYD PUMP Switch; HYDR PRESS Lights

Pilot's Manual

Learjet 60
GINE FIRE
EXTINGUISHING) .
The valves operate on
28 VDC sup-
plied through
the 7 .5 amp
L and R FW SOV
circuit breaker on
the pi-
lot's
and copilot's circuit
breaker panels
respectively . Loss of
power
causes
the shutoff
valves to remain in
their last position .
The firewall
shutoff valves are
operative
during EMER BUS
mode .
The system
is serviced
through a ground
service access
located below
the
right engine
pylon . The
service access includes
quick-disconnect
ports for
pressure and return
lines, an air
valve for accumulator
charging,
and a direct-reading
accumulator
pressure gage
.
HYDPUMP
SWITCH
The
auxiliary hydraulic
pump is controlled by
the HYD PUMP
switch
located
on the center
switch panel .
When the switch is
placed in the
On
(HYD PUMP)
position,
the auxiliary hydraulic pump
is cycled by
a pressure
sensing switch
plumbed into
the high-pressure side
of the
system
. The pressure
switch will
energize the auxiliary
hydraulic
pump if
system pressure
drops below approximately
1000 psi and
then
de-energize the pump
when system
pressure rises above
approx-
imately 1100 psi .
The auxiliary
hydraulic pump is plumbed
to pro-
vide hydraulic
pressure for the
landing gear, wheel
brake, and flap
systems
only and will not supply
pressure for
operation of the spoil-
ers
or thrust reversers
. The auxiliary
hydraulic pump operates on
28
VDC supplied
through a 50-amp
current limiter and is
available
' when
EMER BUS is selected
. Refer to Airplane
Flight Manual for hy-
draulic pump limitations .
HYDR
PRESS LIGHTS
Illumination of
the amber L and R
HYDR PRESS lights on the
glare-
shield annunciator
panel indicate low hydraulic system
pressure from
either the left or right
engine driven pump
respectively . The lights
are
operated by
the hydraulic pump
pressure switches that sense
hy-
draulic
pressure provided by
each engine-driven pump .
The L or R
HYDR PRESS light
will illuminate when hydraulic
system pressure
drops below
approximately 150 (±50)
psi in the engine-driven hy-
draulic pump line .
HYD PRESS INDICATOR
The HYD PRESS
indicator is a vertical-scale instrument
and is located
on the center switch
panel adjacent to the
auxiliary hydraulic pump
and
anti-skid switches . The indicator
face consists of a vertical scare
marked from 0 to 2000 psi
in 500 psi increments and a pointer at the
right margin of the instrument .
The instrument is operated by a
pres-
sure transducer plumbed to
the high-pressure side of the hydraulic
system in the gear, flap
and brake part of the circuit . The indicator op-
erates on 28 VDC supplied
through the 1-amp HYDRAULIC PRESS
IND circuit breaker on the copilot's circuit breaker
panel . Refer to Air-
plane Flight Manual for instrument limit markings .
3-2
PM-123
Change 2