(13), and open the ship/shop air supply valve.
Oxygen Boost Pump Shutdown.--Use the
The boost pump drive pressure gauge (12)
following steps to shut the oxygen servicing unit down
should indicate 90 to 150 psi.
after using the boost pump to recharge an external
5. Open the boost pump drive valve (15), which
system:
allows the air to flow to the boost pump. The
1. Close the oxygen servicing unit servicing valve
boost pump (21) should begin to operate. The
(34).
pilot valves will function to control the
operation of the boost pump as previously
2. Close the nitrogen boost pump drive valve (15).
described.
3. Close the nitrogen cylinder valves (3) or
6. Verify that a pressure of 2,300 to 2,500 psi is
ship/shop air supply valve.
indicated on the oxygen module regulator inlet
4. Close the oxygen cylinder valve (4).
pressure gauge (29).
5. Open the oxygen vent valve (28).
7. Rotate the handle of the oxygen regulator (30)
6. Open the nitrogen boost pump drive vent (16).
clockwise until the regulator outlet gauge (31)
indicates the desired pressure.
7. Rotate the handle of the oxygen regulator (30)
counterclockwise and hold it in this position
8. Purge the servicing hose assembly, and continue
with the servicing operation as previously
until the oxygen regulator outlet pressure gauge
described.
indicates zero.
S H U T D OW N P RO C E D U R E S . -- To avo i d
8. Close the oxygen vent valve (28) when the
injury to personnel and damage to equipment, the
oxygen supply pressure gauge (19) and
oxygen servicing unit must be properly shut down after
regulator inlet pressure gauge (29) indicate zero.
an external charging operation. The shutdown
9. Close the boost pump drive vent (16) when the
procedures to be used depend on the method of
nitrogen supply pressure gauge (6) and boost
servicing used--pressure equalization or boost pump.
pump drive pressure gauge (12) indicate zero.
Pressure Equalization Shutdown.--Use the
10. If open (depending on whether ship/shop air was
following steps to shut the oxygen servicing unit down
after using the pressure equalization method for
used), close the nitrogen supply valve (7).
recharging an external system:
11. Position the oxygen selector valve (20) to OFF.
1. Close the oxygen servicing unit servicing valve
12. Disconnect the servicing adapter and hose
(34).
a s s e m b l y a n d s t ow t h e m a s p r ev i o u s l y
2. Close the oxygen cylinder valve (4).
described.
3. Open the oxygen vent valve (28). The oxygen
RECHARGING THE NITROGEN CYLIN-
supply pressure gauge (19) and regulator inlet
DERS.--Use the following steps to recharge the
pressure gauge (29) should drop to zero.
nitrogen cylinder on the A/U26U-1:
4. Rotate the handle of the oxygen regulator (30)
counterclockwise and hold it in this position
1. Position the servicing unit near the external
until the regulator outlet gauge (31) indicates
nitrogen source and set the brake.
zero.
CAUTION
5. Position the selector valve (20) to OFF.
Ensure that the nitrogen recharging source
6. Position the oxygen vent valve (28) to OFF.
regulator outlet pressure is set at 3,500 psi with a
7. Disconnect the servicing adapter (36 or 38)
pressure relief device set at 4,000 psi.
from the aircraft oxygen storage system.
8. Disconnect the servicing hose assembly (33, 34,
35, and 36 or 38) and store it in the nitrogen
2. Purge the external nitrogen source recharge
module storage compartment.
hose.
10-35
