PS Magazine - TB 43-PS-686
PS, The Preventative Maintenance Monthly
ISSUE 686
JANUARY 2010
8
PS 686
JAN 10
9
PS 686
JAN 10
C
rewmen, if you’re operating your M777A2 howitzer in
very
cold conditions, keep an eye
on the suspension hydrostruts.
Units
at
Ft
Wainwright,
AK,
noticed
Class
III
leaks
coming
from the hydrostrut vent ports
when they tried to raise howitzers
that had been stored outdoors in
temperatures below -10°F.
Turns out there’s a slight
problem
between the hydraulic fluid and
the hydrostrut piston seal, NSN
5330-99-679-8380. Over time, the
seal loses its elasticity, especially in
extremely cold weather. That can
create leaks when the thermometer
takes a nose dive.
If you notice a Class III leak at the hydrostrut vent valve, stop trying to raise the howitzer
immediately. Lower the howitzer to the ground using the suspension levers and take the
following action:
1.
Deploy the wheel arm assemblies into the raised position, like it says on Page 2-124
of TM 9-1025-215-10 (Jun 06 w/Ch 3, Jul 08).
2.
Return the wheel arm assemblies to the towing position (Page 2-175).
3.
Try to build pressure with the suspension pumps, then relieve the pressure using
the suspension levers.
Repeat these steps several times. That should energize the seals and help stop the
hydraulic fluid leak. Once you’re ±nished, make sure you check the suspension oil fluid
level. If it’s low, notify your mechanic.
In most cases, hydrostrut leaks will stop by themselves when temperatures warm up. So
keep this in mind before going beyond crew-level maintenance.
You’ll ±nd the complete scoop in TACOM Maintenance Action (MA) message 09-032:
T
he elevation fring stop—also known as the taboo gear—is designed to keep your
M119A2 howitzer From fring when the gun tube is elevated too high.
But the stop can’t do its job iF you don’t keep it lubed. In Fact, without regular
lubing, the stop will stick. IF that happens, the howitzer will fre past 1244 mils
oF elevation. The cannon tube will Fall out-oF-battery iF the recuperator is low on
nitrogen or the stowage/stop gun tube—also known as run back stop—is not in place.
Someone could get hurt!
Avoid that problem by making sure you lube the elevation fring stop weekly with
WTR, NSN 9150-00-944-8953. Then make sure you check the stop beFore every
operation Following the instructions in PMCS Item 21 in WP 0040 00-18 oF TM 9-
1015-252-10 (Jun 06 w/Ch 1, Jan 07).
M777A2 Towed Howitzer…
Cold Weather
Can Cause
l
e
a
k
s
M119A2 Towed Howitzer…
Stuck Stop a Real
Show Stopper
Class III leak from hydrostrut assembly?
the hydrostrut
assembly is
leaking like a
sieve!
how are we
ever gonna
raise this
howitzer?
Lube elevation ±ring stop weekly with WTR
let’s
get
ready
to fire!
wait!
you might
want to check
my elevation
first!
my firing stop
is
stuck!
686.08-09.indd
1-2
11/23/09
2:18:51 PM
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