TM 55-1510-220-10
Table 3-3. Malfunction Indications and Procedures
Mode of
Malfunction
Operation
Indication
Procedure
Probable Cause
STBY or ALIGN
WARN on, CDU blank (DIM
1. Rotate MSU mode selector OFF
Automatic shut-
control clockwise), MSU BAT
down caused by
off.
overtemperature.
2. Check aircraft cooling system and cor-
rect if faulty.
3. Realign INS.
STBY, ALIGN, NAV
WARN on, MSU BAT on,
1. Rotate MSU mode selector OFF
Loss of INS power
CDU blank.
and low battery
2. Insure all switches and circuit break-
Unit (BU).
ers applicable to INS operation are set
properly
3. If in flight, rotate MSU mode selector
OFF
4. If on ground, replace battery unit. Bat-
tery unit test may be by-passed by ro-
tating mode selector to OFFE then to
NAV and reloading position coordi-
nates. When INS advances to align-
ment State 7 (PI=7) rotate mode
selector to ALIGN.
STBY, ALIGN, or NAV
WARN on, CDU is operating
Perform Malfunction Code Check as
Navigation fail-
cribed in Table 3-2
ure or interfacing
em problem.
Table 3-4. Action Codes and Recommended Action
Code
Recommended Action
01
Shut down INS
02
Watch for degradation (NAV). During ground operation, downmode to STBY and restart alignment.
03
INS may be used for navigation. One or more analog outputs are not functioning properly Check 26VAC circuit
breakers, HSI and autopilot.
04
Downmode to STBY and restart alignment (ground operation only).
05
Correct problem in interfacing system (could be INS). Will not seriously affect performance.
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