PS Magazine - TB 43-PS-665
PS, The Preventative Maintenance Monthly
ISSUE 665
APRIL 2008
24
PS 665
APR 08
I
f your Avenger is equipped with the slew-to-cue conFguration, that means it’s also
equipped with the inertial reference unit (IRU). The IRU is going to need a bit of
tender, loving care if it’s going to help point the Avenger in the right direction.
TLC begins with proper installation. The IRU is mounted to the HMMWV with
three mounting bolts. The bolt on the rear driver side of the IRU is not easily accessible
and isn’t checked often. If it’s missing or loose, the IRU vibrates during operation
and travel. This vibration hurts the performance of the LNS (land navigation system)
and can damage the IRU.
During
PMCS,
make
sure
all
three bolts are present and tight. The
easiest way is to just feel the IRU for
looseness.
Also check that the distance measuring
unit (DMU) is installed and its cable is
connected. Without the DMU, the IRU
won’t know how far you’ve traveled.
Make sure the GPS receiver is com-
municating with the IRU by checking
the control display terminal (CDT). The
IRU should be in the NAV/GPS mode.
If the IRU is in the NAV mode only, it’s
not talking to the GPS receiver. Tell your
repairman.
±inally, ensure that the GPS receiver
antenna is mounted in the right spot. It
should be here.
..
...not here.
Avenger Missile System…
IRU
Needs
TLC
when you remove
the Iru, use a
little more tlc.
and
remember,
only one
Iru to a
box.
Store and
transport
it only in a
box thickly
lined with
foam.
since I have this
slew-to-cue, I’m
going to need more
care, especially
for my Iru.
are you
reading
me?
loud
and
clear.
Make sure all three mounting bolts
are tight. Feel IRU for looseness
DMU cable
connected?
IRU should be in NAV/GPS mode
WRONG
Right
665.24-25.indd
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3/4/08
5:28:54 PM
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