PS Magazine - TB 43-PS-581

PS, The Preventative Maintenance Monthly

ISSUE 581

APRIL 2001
PS Magazine - TB 43-PS-581 - Page 27 of 32
PS 581
APR 01
51
AN/PVS-14 NVD.
..
What You
Don’t
See…
C
leaning the lens on an AN/PVS-14
night vision device (NVD) is the user’s
responsibility. But many of you are tak-
ing that responsibility too lightly.
Clean the lens with lens paper, NSN
6640-01-459-4239, and water. Never
clean the lens dry! Dirt pushed across a
dry lens will scratch it. In a pinch, you
can use your hot breath to create mois-
ture on the lens. But don’t do this in cold
weather. Warm moisture hitting the cold
glass could crack the lens.
PS 581
APR 01
50
Environmental Control Units…
If you’re cleaning the lens demist
shield, NSN 5855-01-246-8272, dry is
the way to go. The demist shield is coat-
ed to prevent the lens from fogging. If
you clean the shield using water or your
breath, you’ll damage the coating.
Brush the demist shield clean with
lens paper like you’d sweep a floor. If
you can’t get it clean, turn it in to your
C & E shop for a new shield.
While you’re cleaning the lens, don’t
forget the sacrificial window. Sacrificial
windows
should
get dirty in the field
because they’re used during adverse
conditions to protect the lens. Use wet
lens paper to do the cleaning job.
When the NVD is not in use, make
sure to keep the lens cap, NSN 5340-01-
397-6608, on. Dirt buildup and scratch-
es happen only to uncovered lenses.
…Can
Hurt
You
Clean lens with
lens paper
Clean
sacrificial
window
wet
Keep
lens cap
on
Clean demist
shield dry
Warm
Before
You Cool
Warm
Before
You Cool
E
nvironmental control units (air condi-
tioners) need a warmup before you make
operational checks following extended
shutdowns or initial installation.
A warmup is required in order to boil
out liquid refrigerant that tends to
migrate into the ECU’s compressor and
mix with lube oil there.
If the refrigerant is not boiled out
before an operational check in the
COOL mode, it can cause loud knock-
ing and even failure of the compressor.
So before you make any operational
checks according to TM procedures,
make sure to power up your ECU fol-
lowing the times in the chart below.
Outside
Temp
Minimum Input
Power Time
60° F
5 minutes
40° F
1 hour
20° F
2 hours
Below 20° F
4 hours
581. 50-51 (C)
2/26/01
4:48 PM
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