Piper Arrow IV, Maintenance Manual

Page: 461 / 752

CHART 3503. FILLING PRESSURE FOR CERTAIN AMBIENT TEMPERATURES
Ambient Temperature Filling Pressure Ambient Temperature Filling Pressure
0 1650 (PSI) 70 1975 (PSI)
10 1700 80 2000
20 1725 90 2050
30 1775 100 2100
40 1825 110 2150
50 1875 120 2200
60 1925 130 2250
NOTE: Filling pressures are for 1850 PSI at 70°F. Table assumes 25°F rise due to heat of compression with max fill rate.
2. If a cylinder has less than 5 psi pressure or has insufficient pressure to produce an audible hissing
sound when the valve is cracked, it should be removed and/or purged, and if the condition has existed for a
significant length of time, hydrostatically test.
3. Make sure both the charge valve and recharge “cart” fittings are clean and free of contamination.
—WARNING—
BE CERTAIN THERE IS NO OIL ON THE FITTINGS OR
NEAR THE IMMEDIATE VICINITY.
4. Attach service cart hose to recharge port. Fill the system at a rate not exceeding 200 psig per minute
proceeding as follows:
A. To obtain the correct filling pressure for the oxygen system at various ambient temperatures, a
table is included for your convenience. The pressures given are not exact, but sufficiently accurate
for practical purposes of working pressures between 1800 and 2400 psig cylinders. The cylinder
should be allowed to cool to a stabilized temperature after filling before checking against the
valves in Chart 3503.
B. When using a recharge unit consisting of one supply cylinder, slowly open the valve of the supply
unit and allow the oxygen to transfer.
C. When using a recharge unit consisting of two or more supply cylinders (cascade storage system), it
is recommended that the following procedure be used:
(1) Before opening any valves, check the pressure remaining in the airplane’s oxygen cylinder. If
it is partly charged, note the pressure indicated on the cylinder gauge. Then open and close
each valve on the cascade storage system and determine which cylinder has the lowest
pressure. When found if this cylinder has a pressure lower than the oxygen cylinder in the
aircraft, do not attempt using it for filling; use the storage cylinder that has a pressure higher
than the aircraft’s cylinder but lower than the others.
(2) Open the valve on only the one storage cylinder with the lowest pressure. When the pressure
indicated on the aircraft’s oxygen gauge and charging gauge has become equal, close the valve
of the storage cylinder; then go to the storage cylinder with the next higher pressure and repeat
the procedure.
(3) If after using the last storage cylinder the aircraft’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.
35-10-16
Page 35-16
Added: November 6, 1979
2H14
PIPER AIRCRAFT
PA-28RT-201 / 201T
MAINTENANCE MANUAL