Piper SARATOGA PA-32-301 Maintenance Manual page 389

PIPER AIRCRAFT
PA-32-301/301T
MAINTENANCE MANUAL
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 tested.
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 values 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 still 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.
(4) A good deal of oxygen will remain in the large cylinders used in the cascade system after
filling only one of the cylinders but such remaining oxygen will be at a pressure something
less than the 1850 psi which is not sufficient pressure to completely refill another aircraft
cylinder, although it will refill several small cylinders.
(5) It is not economical even on a three or four cylinder cascade system to begin recharging
with oxygen at less than 300 psi pressure in the 300 cubic foot bank of cylinders. So use 300
cubic foot cylinders down to approximately 300 psi; then return for refilling. In two
cylinder systems use to approximately 100 psi; then return for filling.
D. When the pressure gauge on the recharge unit or in the aircraft reaches 1800 to 1850 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 the cylinder pressure according to Chart
3503 after the cylinder temperature stabilizes.
5. After detaching the service cart, cap hose and fittings to prevent contamination.
6. Perform a leak check of the high pressure lines and clean off solution afterwards. If solution is not
properly cleaned off, unusual corrosion may result.
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Added: May 21, 1980
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