PS Magazine - TB 43-PS-625
PS, The Preventative Maintenance Monthly
ISSUE 625
DECEMBER 2004
Initial issue to units will be configured
with quick disconnect fittings based on
the helicopter models in the unit.
For the AGPUs, you’ll get a quick dis-
connect coupling used to fill AGPU
reservoirs.
The basic RSU, NSN 4940-01-504-
5279, is stocked without quick discon-
nects, but they are listed separately in the
commercial manual as stocked items.
NSNs are also available on the follow-
ing: output hose, NSN 4720-00-484-
5765, clear return tubing, NSN 4720-01-
038-2651; and hose fitting, NSN 4730-
00-472-4093.
PS 625
DEC 04
37
•
The steps on flushing the hose, filling the reservoir, and stowing the output quick
disconnects are listed on the reservoir’s decal.
•
Fluid is dispensed from the RSU using a manual pump, with a 200 psi output
pressure.
•
The output hose is fitted with a 2-micron filter to control solid contamination.
•
A bulkhead connector and a return tube are provided to allow the output hose to
be flushed prior to connecting to a bird.
•
The return tube is transparent so that hydraulic fluid can be checked for air
bubbles.
•
The aircraft reservoir is filled by pumping the fluid through the quick disconnect
fitting on the ground support return port for the hydraulic system to be serviced.
•
The RSU delivers 4 cubic inches of fluid per stroke or a quart per 17 strokes.
The only maintenance requirement for AVUM is to replace the filter element in the
output hose. But always make sure the RSU uses MIL-PRF-83282 as it says on the
factory-applied label, since this fluid is used in all helicopter flight control systems.
Keep in mind that brakes use a different type of fluid, MIL-PRF-5606. For now,
stay with the filter and bleeder assembly, NSN 4910-00-245-1832, to service brake
systems.
When you
operate the
RSU for the
first time, here
are some points
to remember.
this is a
lot
better,
faster and
easier
than
the old way!
The RSU can service the other
aircraft like the Apache through
the GSE return or by dispensing
fluid into the fill reservoirs.
Kiowa Warrior
helicopters
also use open
reservoir
dispensing.
Service hydraulic
system following
commercial
manual directions
…and
never
use
the same rsu on the
brake system because
your brakes use
different fluid.
that’s a fact!
but follow the
instructions on
the decal…
Black Hawks and
Chinooks have
built-in fill
pumps with open
reservoirs that
mechanics can
easily fill from
quart cans.
The RSU
can be used
on
all air-
craft,
but
it is most
useful when
servicing
the Apache.
625.36-37(C!)
10/29/04
2:56 PM
Page 1
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