The INS can provide test signals to the
Horizontal Situation Indicator (HSI) and
connected displays. Pressing TEST switch
during Standby, Align, or NAV mode causes
all digits on connected digital displays to
indicate "8's," and lights the HSI and the
ALERT lamp. Additional HSI test signals are
provided when INS is in Align and data
selector is at any position other than
pressing TEST switch causes HSI to indicate
heading, drift angle, and track angle error all
at "0°" or "30°." At the same time, cross
track deviation is indicated at "3.75" nautical
miles (one dot) right or left and INS-
controlled HSI flags are retracted from view.
Output test signals are supplied to the
autopilot when INS steering is selected.
Rotating AUTO/MAN switch to AUTO and
pressing TEST during Align furnishes a 15°
left bank steering command. A 15° right
bank steering command is furnished when
AUTO/MAN switch is set to MAN.
The quick test procedure may be performed
any time after Alignment State "8" is reached
and prior to entry into NAV.
1. Mode selector ALIGN.
(Observe CDU displays are illuminated.)
2. Data selector DSRTK/STS
(monitor right data display until
State "8" (or lower) is reached.)
(Observe right data display is ---N4,
where "N" is not "9".)
3. AUTO/MAN switch MAN.
4. INS Couple to flight director and
autopilot, as applicable.
5. Data selector Set to any position
6. TEST switch Press and hold.
After performing the preceding
All lamps illuminated.
All lamps illuminated. All "8's"
All angles 30°. Cross-track devia-
tion bar is one dot right. All INS
flags are retracted.
A 15° steering command is is-
LINK UPDATE annunciated.
TACAN UPDATE annunciated.
7. CDU TEST switch Hold depressed,
and rotate AUTO/MAN switch to
(Observe all indications are as in step (6) except a
15' left steering command is issued. On HSI, All angles
are "0°" and cross-track deviation bar is one dot left.)
8. CDU TEST switch Release. If
desired, decouple INS.
(Observe operation returns to normal.)
pushbutton, any incorrectly loaded data can
be corrected by pressing CLEAR pushbutton
and reloading correct data.
alignment, encoding altimeter will supply
the field elevation (aircraft altitude) into INS.
Once present position has been inserted
and computer has advanced to alignment
state "7", present position cannot be
reinserted without downmoding to STBY
and restarting alignment.
If longitude and latitude coordinates are
being used, skip step 8 (a) and proceed with
step 8 (b).
Insert UTM coordinates of aircraft
1. Data selector UTM POS.
(Observe that prior to initial load, INSERT/
ADVANCE pushbutton light illuminates.)