PIPER SENECA II SERVICE MANUAL
XIV - ACCESSORIES AND UTILITIES 01/01/09
3C22F
WARNING: BE CERTAIN THERE IS NO OIL OR OTHER PETROLEUM BASED MATERIAL
ON THE FITTINGS OR NEAR THE IMMEDIATE VICINITY.
d. Attach service cart hose to recharge port. Fill the system at a rate not exceeding 200 psig per minute
proceeding as follows:
1. 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 TABLE XIV-VIIIA.
2. When using a recharge unit consisting of one supply cylinder, slowly open the valve of the
supply unit and allow the oxygen to transfer.
3. When using a recharge unit consisting of two or more supply cylinders (cascade storage
system), it is recommended that the following procedure be used:
a. 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.
b. 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.
c. 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.
d. A good amount of oxygen will remain in the large cylinders used in the cascade system
after filling only one of the cylinders. This remaining oxygen will be at a pressure
something less than the 1850 psi. This is not sufficient pressure to completely refill
another aircraft cylinder, although it will refill several small cylinders.
e. 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.
4. 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 Table XIV-VIIIA after the cylinder temperature stabilizes.
e. After detaching the service cart, cap hose and fittings to prevent contamination.
f. Perform a leak check of the high pressure lines and clean off solution afterward. If solution is not
properly cleaned off, corrosion may result.
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