Piper PA-24 Comanche Service Manual page 64

PIPER COMANCHE SERVICE MANt"AL
I. Before opening any valves, check the pressure remaining in the airplane's oxygen cylinder. •
i" st ill pa nlv cha rged. note the pressure indicated on the cylinder gauge. Then open and close each \ alve on th,
ca ...cadc storage ...
~
...
tern
and determine which cylinder has the lowest pressure. When found. if this cylinder has
a pressure lower than the oxygen cylinder in the airplane. do not attempt using it forfilling. Lse the storage
cylinder that has a pres!>urc higher than the airplane's cylinder but lower than the others.
"'l
Open the
valve
on only the one storage cylinder with the lowest pressure. When the
pre-sure
indicated on the airplane's oxygen gauge and charging gauge has become equal. close the
valve
of the ...torage
cylinder. then go
In
the storage cylinder with the next higher pressure and repeat the procedure.
J.
If. after using the last storage cylinder. the airplane's oxygen system is still not fully charged. a
full storage cylinder should be put in place of a cylinder with the lowest pressure and used in the same manner.
4. A good deal of oxygen will remain in the large cylinders used in the cascade system after filling
only one of the
c~
linders, but such remaining oxygen will be at a pressure something less t han the 1l<00 pound
"I.
which i"l not sufficient pressure to completely refill another aircraft cylinder. although it will refill ..
evcral
smaller cylinder...
5.
It is not economical, even on a three or four-cylinder cascade system. to begin recharging
w ith
oxygen at b . . . than .'\00 psi pressure in the 300 cubic foot bank of cylinders. So. use JOO cubic foot cylinder...
dow n
In
approximately
JOO
psi. then return for refilling. In two-cylinder systems. use to
approximately
600
pvi,
then return for filling.
C' . When the pressure gauge on the recharge unit or in the airplane reaches 1800 psi. close the pressure
regulator
valve
on the recharge unit. Disconnect the filler hose from the filler valve. replace the
protective
cap
on the filler valve and close the access cover. Check cylinder pressure against chart after cylinder temperature
. . . tabilize ....
2-59. Inspection and Overhaul Time Limits. It is recommended that inspection and
overhaul
be conducted
b~
an FA.-\ Approved Station of the manufacturer. Scott Aviation. The following checks and chart
gi .
recommended inspection and overhaul time for the various parts of the oxygen system.
a. ThC' oxygen
c~
tinder can be identified by the ICC or DOT identification stamped on the cylinder.
The standard wciuht cvlinder
lice
or DOT :lAA 1800) must be hvdrostatic tested at the end of each 5
vear
period. The
tight\~eigh't
cylinder (ICC or DOT :lHT 1850) must be tested every 3 years. The month and vear
of the la...t test is stamped on the cylinder beneath the
lec
or DOT identification.
h. The outlets should be checked for leakage both in the non-use condition. and for leakage around an
inserted connector.
c. The high pressure gauge may be checked for accuracy by comparing its indicated pressure with
that of a uauue of known accuracv.
d.
~I
nspection of the regulator may be effected by introducing into an outlet a mask connector to which
is attached a 100 psi gauge. With one other outlet flowing through a plugged in mask. the indicated regulator
output pn:"... urc ... hall he not less than 45 psig at sea level with 200 psig supply cylinder pressure. It should be
noted that the permissible leakage through the I 16 diameter vent hole in the side of the upper regulator
hou ... ing i... 10
I;C
min. maximum. when the regulator is turned on. There shall be no external leakage any where
on the regulator when il is turned off. All fittings shall be leak free.
ADDED: 4/3/78
lC14
•
HA:'\DLlNG
A~D
SER\'ICT\G