The masks must not be set to EMER while
stowed, or the oxygen supply will be quickly
depleted. However, once the mask is donned,
if the diluter demand function does not appear
to be working properly, or if smoke/fumes
are present, the emergency position should be
selected.
PASSENGER DISTRIBUTION
SYSTEM
The passenger distribution system (Figure 17-
1) is used to provide oxygen to the passengers
in case of a pressurization system malfunction
or any other time deemed necessary. Oxygen
is available to the crew, on demand, provided
the oxygen cylinder shutoff valve is open, but
oxygen is not available to the passengers until
it is required.
The passenger oxygen system consists of the
passenger oxygen control valve, passenger
oxygen bleed fitting, six passenger oxygen
mask containers, and twelve passenger oxy-
gen masks.
The passenger oxygen control valve is a two-
way latching solenoid actuated valve and is lo-
cated above the headliner in the cockpit. The
valve is opened automatically by the cabin
pressure controller (when cabin pressure
reaches approximately 14,500 feet) or manu-
ally by the crew if oxygen is required by the
passengers.
The valve is solenoid actuated and DC current
is required. A physical handle is not provided
and DC electrical power from the EMER BATT
BUS is required to automatically or manually
d e p l o y t h e p a s s e n g e r o x y g e n m a s k s .
Automatic operation of the valve is controlled
by the cabin pressure controller (CPCS), which
also provides failure detection.
On aircraft 45-170 and subsequent, and some
earlier aircraft, an altitude compensating reg-
ulator has been added downstream of the pas-
senger oxygen control valve. This regulator
reduces the oxygen flow to the passenger
masks when at lower cabin altitudes. This ef-
fectively increases the oxygen duration. The
AFM
/Checklist provides oxygen duration
charts for modified and unmodified aircraft.
The checklist also provides tabular oxygen
duration for flights above FL410 when one
crewmember is wearing an oxygen mask and
cabin pressure is normal. This data is pro-
vided for modified and unmodified aircraft.
The passenger oxygen bleed fitting is used to
relieve pressure in the distribution system,
following deployment of the masks, to allow
the masks to be replaced inside the contain-
ers (Figure 17-11).
Two passenger oxygen masks are stowed in
each passenger oxygen mask container, lo-
cated within the passenger cabin and the lava-
tory headliners. The masks drop from the
containers when the passenger oxygen control
valve is opened. Each passenger must pull the
oxygen mask lanyard to remove a pin and ini-
tiate the flow of oxygen to their mask.
To prevent injury to crew members
and passengers from a potential
flash fire, all smoking material must
be extinguished prior to the use of
oxygen.
The passenger oxygen distribution system can
be manually or automatically controlled to
deploy the passenger oxygen masks.
Operation of the passenger oxygen distribu-
t i o n s y s t e m i s c o n t r o l l e d t h r o u g h t w o
switch/indicators (S/I) on the PAX OXYGEN
and PRESSURIZATION control panel (Figure
17-12). The PAX OXY/AUTO switch is blank
when the automatic feature is armed, and il-
luminates OFF when depressed. When the
PAX OXY/AUTO switch is depressed it dis-
engages the automatic mask deployment fea-
ture of the system. “OFF” will be illuminated
in the PAX OXY/AUTO switch/indicator when
the switch is selected to OFF.
WARNING
17-10
FOR TRAINING PURPOSES ONLY
L E A R J E T 4 5
P I L O T T R A I N I N G M A N U A L
FlightSafety
international
