TM 55-1510-221-10
Table 3-4. Malfunction Indications and Procedures
Mode of
Malfunction
Operation
Indication
Procedure
Probable Cause
STBY or ALIGN
WARN on, CDU blank
(DIM control clockwise),
MSU BAT off
1. Rotate MSU mode
selector OFF.
2. Check aircraft
cooling system and
correct if faulty.
3. Realign INS.
Automatic
shutdown
caused by
over-temperature.
STBY, ALIGN, NAV
WARN on, MSU BAT on,
1. Rotate MSU mode
Loss of INS
CDU blank.
selector OFF.
power and low
battery
2. Insure all switches
Unit (BU).
and circuit breakers
applicable to INS
operation are set
properly.
3. If in flight, rotate
MSU mode selector
OFF.
4. If on ground, replace
battery unit. Battery
unit test may be by-
passed by rotating
mode selector to
OFF, then to NAV
and reloading
position coordinates.
When INS advances
to alignment State 7
(PI=7) rotate mode
selector to ALIGN.
STBY, ALIGN, or NAV
WARN on, CDU is
Perform Malfunction
Navigation
operating
Code Check as
failure or
described in Table 3-2.
interfacing
system problem.
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