NAVIGATION AND
COMMUNICATION
AIRPLANE
OPERATIONS
MANUAL
2-18-11
Page
52
Code
01
REVISION 31
MAINTENANCE PAGE (POWER ON SELF-TEST)
1 - TEST PAGE IDENTIFICATION
− Indicates where a failure has been detected.
− Color: White.
2 - FAILURE SIDE IDENTIFICATION
− Indicates the side of the detected failure.
− Color: Green.
3 - FAILURE IDENTIFICATION
− Identifies the detected failure according to the table below.
− Color: Red.
ERROR
MESSAGE
MEANING ACTION DECISION
RMU ERR
One or more
internal
parameters were
measured and
found to be
outside their self-
test limit.
1. Check that CDH is not in
EMERG Mode.
2. On main tuning page,
perform tuning test on all
radios by setting fre-
quency and determining
that radio is operating.
If tuning test fails,
the RMU is not
fully operable.
PRI BUS
Full RMU com-
munications with
all COMs, NAVs,
and cross-side
RMU cannot be
established on the
primary bus.
1. Check that all radio
circuit breakers are on.
2. Check RMU ON/OFF
Page for all functions
ON.
3. Check that CDH is not in
EMERG Mode.
SEC BUS
Full RMU com-
munications with
the on-side COM
and NAV cannot
be established
using the secon-
dary bus.
4. If 1 or 2 (or 3 if installed)
are sources, correct and
turn RMU power off for
10 seconds. Reapply
power to start new
POST.
5. If error persists,
Any of these
messages indi-
cate that system
redundancy has
been reduced.
NAV UNIT/
COM UNIT
The NAV units
and/or COM units
cannot fully
communicate with
both RMUs over
primary bus and/or
the on-side RMU
over secondary
bus.
perform on-side and
cross-side tuning off all
radios and activate
auxiliary tuning sources
to determine which
functions are still
available.
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