TM-9-2350-311-10
HOWITZER, MEDIUM, SELF-PROPELLED, 155MM; M109A2, M109A3, M109A4 AND M109A5
TECHNICAL MANUAL; OPERATOR’S MANUAL
NOVEMBER 1994
TM-9-2350-311-10 - Page 436 of 775
TM 9--2350--311--10
3--36
3--6
ARMAMENT AND CAB MAINTENANCE
3--6.1
Maintenance of Sighting and Fire Control Equipment
a. Inspection
Whenever inaccuracies, maladjustments, or other conditions affecting the serviceability are evident, the equipment
should be referred to unit maintenance.
Check instruments for completeness and appearance. Painted surfaces should be free of wear, scratches, or chipped
or loose paint. All graduations, lettering, and indexes must be clear and distinct. There must not be evidence of
corrosion on any part.
There must be no dirt, smears, stains, scratches, digs, condensation, fungus growth, chips, fractures, or cement
separations visible through optics.
b. Care
Rough or careless handling can cause inaccuracy of the sighting and fire control instruments.
The following points will keep your equipment in working order:
1
Don’t force rotation of any knob beyond its stop limit.
WARNING
Don’t point an optical instrument directly at the sun without using a filter. The heat of focused
rays may damage eyes and optical elements.
2
Keep instruments as dry as possible. If wet, dry before stowing in carrying case. Condensation may
collect on optical parts when temperature of parts is lower than surrounding air. Moisture can be
removed by placing instruments in a warm, but not hot place. Heat can cause unequal expansion of
parts, resulting in damaged optics.
CAUTION
•
To prevent damage to components, under no circumstances should polishing liquids,
pastes, or abrasives be used for polishing lenses and windows.
•
For wiping optical parts, use lens paper (item 33, Appx D) especially intended for cleaning
optical glass. To prevent damage to components, don’t use silicone treated paper that is
used for eyeglasses.
3
Keep optical parts free of oil and grease. Don’t touch lenses or windows with fingers. To remove oil or
grease from optical surfaces, apply optical lens cleaning compound (item 9, Appx D). If cleaning
compound is not available, and temperature is above freezing, breathe heavily upon glass and wipe off
with clean lens paper (item 33, Appx D).
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