PS Magazine - TB 43-PS-602
PS, The Preventative Maintenance Monthly
ISSUE 602
JANUARY 2003
•
Remember, mechanics, that maximum hydraulic operating pressure is different
for some aircraft. It’s 1,000 psi on the OH-58D and 3,000 psi on AH-64s, UH-60s
and CH-47Ds.
•
When you start an AGPU, you get three tries of 30 seconds each. Then you must
wait 20 minutes for the starter to cool down before you try to start the AGPU again.
If it fails to start on the fourth try,
stop
and let your AVIM shop know you have a
problem before you attempt another start.
•
If you have to start an AGPU from a DC generator, you only get two tries of 30
seconds each. Then you have to wait 20 minutes for cool-down. The next start up
attempt, you get two tries of 15 seconds each. Still doesn’t start? Let your AVIM
shop know.
•
If you slave an AGPU from a battery, the start-up procedure is different. You get
three attempts of 30 seconds each. Then you wait 20 minutes and make two more
attempts for 30 seconds each. Nothing? Your AVIM shop needs to find the problem.
•
Check the AGPU frame, housing and doors. Look for dents, cracks, punctures,
corrosion, damaged or broken hinges, latches and braces.
•
Eyeball the control panel for cor-
rosion, missing parts, or cracked or
broken glass on the gauges.
•
Check the battery for a loose or
missing holddown or guide, missing
or damaged vent drain tubes and
loose or damaged connectors. Check
the electrolyte level, too.
•
Inspect the engine compartment
for oil or fuel leaks, corrosion in the
air intake duct, loose or missing
bolts, or damaged hoses.
•
Check out the hydraulic compart-
ment for leaks, low fluid levels,
cracked gauge glass and damaged or
corroded fittings.
•
Check all cables and hoses for
torn or worn insulation, loose clamps
or missing spiral wrap and netting.
•
Look for loose or missing fasten-
ers, bent or broken springs, broken
or loose terminals, and loose or
missing brush terminals.
PS 602
JAN 03
38
PS 602
•
AGPUs can be driven in two modes. The primary mode is with the engine run-
ning to provide DC power to the propulsion system. The alternate mode is without
the engine running and operating on battery power. Here’s where the rubber meets
the road:
Always
use the primary mode if you’re propelling your AGPU for more
than 500 feet, like going to the far end of the flight line.
Never
use battery power to
propel an AGPU for long distances. That will drain the battery.
•
Don’t use the M4K or
other 4,000-lb forklift to
lift an AGPU. A loaded
AGPU weighs 4,275 lbs
and pushes the limit of
an M4K. If loading oper-
ations require moving an
AGPU, use a 6,000-lb
capacity forklift.
Hydraulic and Operating Tips
•
Before operating an AGPU, make sure the hydraulic reservoir is at
3
⁄
4
full.
•
Check the desiccant in the vent
dryer, too. If it’s less than 25 per-
cent blue, add fresh desiccant,
NSN 6850-00-680-2233. If you
have no desiccant on hand, fire up
the nearest oven and bake the old
desiccant at 350° for 4 hours or
until the original blue color returns.
•
Make sure hoses have no kinks
or breaks. Make sure all connec-
tions are tight.
Check
desiccant
for color
These tips will
get your abused and
neglected AGPU off
the endangered
equipment list.
good, control
panel is
good
to go!
oof!
I
think I
hurt
myself!
your
cables
look
good!
then
what are
we waiting
for!?
let’s start
up some
birds!
Hydraulic fluid
is pressurized
up to 3,300 psi.
Always wear
gloves and eye and
ear protection
when operating the
hydraulic system.
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