Learjet 60 - Oxygen Pressure Indicator; Oxygen System Cockpit Controls

Pilot's Manual

Learjet 6D
OXYGEN PRESSURE INDICATOR
The vertical-scale oxygen pressure indicator is located on the pilot's cir-
cuit breaker panel . The indicator face is marked from 0 to 2000 psi in
250 psi increments and is controlled byan electric transducer
plumbed
to the high-pressure
side of the shutoff and pressure regulator assem-
bly .
The oxygen supply system may be a single
cylinder or dual cylinder
system . The pressure
indicator is located on the pilot's circuit breaker
panel . In aircraft with dual systems, a second pressure indicator is add-
ed to the pilot's circuit breaker
panel
to
allow
determination of the ox-
ygen pressure in each oxygen cylinder
. The transducer for the aft
oxygen system is wired through a pressure switch to the aft pressure in-
dicator . The pressure switch senses loss of pressure in the aft oxygen
tube . If the aft cylinder is pressurized but the supply tube is not
(for ex-
ample ; due to blockage)
the
indicator will read zero . Since pressure will
vary due to temperature the fore and aft cylinder may not indicate the
same during flight .
OXYGEN SYSTEM COCKPIT CONTROLS
The oxygen system cockpit controls consist of one control valve, la-
beled PASSENGER OXYGEN OFF-AUTO-DEPLOY, located on the
pilot's circuit breaker panel . The control valve controls oxygen avail-
ability
to the passenger oxygen distribution system and provides auto-
matic or manual mode
selection . Oxygen is available to the
crew
oxygen distribution system at all times when the oxygen cylinder shut-
off valve is open . Control
positions
and system functions are as follows :
1 .
With the, PASSENGER OXYGEN valve in the ALTO position,
oxygen is available to the passenger
distribution
system and the
passenger masks will deploy automatically in the event cabin
altitude climbs to 14,500 feet . Should the cabin altitude reach
14,500 (±250) feet, an electrical signal
from the pressurization
indicator will cause the solenoid valve (integral with the
PASSENGER OXYGEN valve) to open, the passenger oxygen
masks will deploy, and the cabin overhead lights will
illuminate
to provide maximum
visibility for donning masks . Normally,
the control should be
in this position .
2 . With the PASSENGER OXYGEN valve in the DEPLOY position,
oxygen is available to the passenger
distribution system and the
passenger masks will deploy . Setting the PASSENGER
OXYGEN valve to the DEPLOY position will manually open
the PASSENGER OXYGEN valve and allow oxygen pressure to
deploy the passenger masks . This position can be
used to
600
PM-123
Change 4