mask deploy and oxygen supply is not avail-
able if DC electrical power is not available.
Depressing the airplane system test switch
with the LTS position selected illuminates the
passenger oxygen deploy switch ON annun-
ciator and the passenger oxygen automatic
mode switch OFF annunciator.
Should the doors be opened inadvertently,
oxygen pressure must be bled from the pas-
senger distribution system before the masks
can be re-stowed. This is accomplished by
opening the passenger oxygen bleed fitting,
after insuring the passenger oxygen control
valve is closed.
OXYGEN DURATION
Before an overwater flight is made, the pilot
should plan oxygen requirements to provide
sufficient oxygen supply for all occupants in
case of a pressurization failure. Additional
oxygen, in the form of carry-on portable units,
may be required to ensure that oxygen dura-
tion and fuel requirements are met. See
A i r p l a n e F l i g h t M a n u a l ,
S e c t i o n I V o r
Supplement section of the Crew Checklist for
Oxygen Duration Charts. Charts are provided
for aircraft 45-170 and subsequent and some
earlier modified aircraft that have the altitude
compensating regulator installed as well as
unmodified aircraft.
The pilot must remember that the crew and pas-
senger masks are not approved for use above
40,000 feet cabin altitude; therefore, if a pres-
surization problem is encountered at high al-
t i t u d e , a n i m m e d i a t e d e s c e n t s h o u l d b e
initiated. Also, prolonged operation of pas-
senger masks above 25,000 feet cabin alti-
tude is not recommended.
Table 17-3 lists the average time of useful
consciousness at various altitudes when the
oxygen system is not used.
17-12
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
45,000 feet............................................................9 to 15 seconds
40,000 feet..........................................................15 to 20 seconds
35,000 feet.............................................................1/2 to 1 minute
30,000 feet...............................................................1 to 2 minutes
28,000 feet...............................................................2 to 3 minutes
25,000 feet...............................................................3 to 5 minutes
22,000 feet.............................................................5 to 10 minutes
Table 17-3. AVERAGE TIME OF USEFUL CONSCIOUSNESS
