will illuminate and not extinguish until the mode selector
is set to OFF. The battery unit should be replaced when
this failure occurs.
(c) Interpretation of failure indications. It is
important to be able to correctly interpret failure
indications in order to take effective action. Failure
indications are listed below under two main categories:
WARN light illuminated, and WARN light extinguished.
Under each of these categories are listed other
indications which will give the operator sufficient
information to take action.
WARN annunciator illuminated.
Take the following action:
If action codes 01,02,03,04 or 05
are displayed - See table 3-2.
No action or malfunction codes
displayed - Indicates computer failure.
Improper displays - Indicates NU
WARN annunciator extinguished.
If CDU displays are blank, incorrect or frozen - CDU
failure is indicated.
If it is not possible to load displays
from the keyboard. A temporary
failure of a numerical key may
prevent data loading. If a number
cannot be loaded into latitude or
pressing/wiggling the key several
momentary hang-up of another key.
To identify the faulty key, rotate the
data selector to DSRTK/STS. The
right digit in right display will
indicate suspect key. Press and
release suspect key several times.
problem is corrected, try pressing
any other numerical key. Its number
should now appear as the right digit.
If this test is successful, press the
CLEAR key and return data selector
to original data loading position.
Otherwise, a CDU failure is indicated.
Table 3-3. Malfunction Code Check
Rotate to DSRTK/STS
RH data display
Action code second and third
Press and release
RH data display
Lowest number malfunction code
which has occurred since this
replaces action code.
Repeat Step 3 repeatedly, recording all malfunction codes until second and third digits again indicate an
action code or go blank. Refer to Table 3-4 for action codes and recommended action and to Table 3-5
for malfunction code definition.
If WARN light extinguishes and two digits go blank, failure was intermittent and has been cleared. If
digits do not go blank, perform action according to displayed recommended action code.