ARMY TM 9-1290-262-24&P
MARINE CORPS TM 00476C-24&P
AIR FORCE TO 49A7-3-72/74
3-7. TEST AND ADJUSTMENT PROCEDURES (cont).
MAGNETIC NEEDLE REPEATABILITY TEST
Rotate aiming circle so that N on housing
1
faces in the general direction of north.
2
Unlock magnetic needle.
3
Look through magnifier (1) and turn aiming
circle to aline end of needle with edge of a
reticle line.
4
Hold steel block (2) close enough to aim-
ing circle to deflect magnetic needle to one
side as far as it will go.
5
Look through magnifier (1), then remove
steel block (2).
6
Observe and note needle position relative
to reticle line after needle has come to
rest.
7
Hold steel block (2) close enough to aim-
ing circle to deflect magnetic needle to
other side as far as it will go.
8
Look through magnifier (1), then remove
steel block (2).
9
Observe and note needle position relative
to reticle line after needle has come to
rest.
10
In steps 6 and 9, needle should return to
its original position within 0.5 mil (the ap-
proximate width of a reticle line). If needle
does not return to its original position with-
in 0.5 mil, notify next higher maintenance
level.
