RMU Self-Test
The radio system has an extensive built-in-test.
A test is initiated when power is turned on
(power-on self-test) and a self-test can be ini-
tiated by the pilot (pilot-activated self-test)
using the TST key on the RMU. If errors are
detected during the power-on self-test, results
will be displayed on a Test Results window and
if no errors are detected, the RMU will display
the radio tuning page. If an error message is
listed, the pilot should note the module asso-
ciated with the error message and verify ac-
c e p t a b l e o p e r a t i o n o f t h a t m o d u l e b y
performing a pilot-activated self-test.
The pilot may initiate a self-test sequence of
any radio function by depressing and holding
the TST key on the RMU after positioning the
cursor inside the window for the function to
be tested. After the test is complete, the green
PASS or red ERR legend will appear in the win-
dow. The errors identified by the self-test in-
dicate one or more internal parameters were
found to be outside the test limits but may not
necessarily indicate non-operation of the func-
tion. The pilot should verify operation of the
function. Pilot initiated tests may also be per-
formed on the VOR, ILS, Marker, DME and
ADF.
RMU POWER SOURCE
The RMUs each have a primary and a sec-
ondary power source. If the primary source is
not available, the RMU will automatically
switch to the secondary power source. RMU
power sources are as follows:
RMU #1 Primary
L ESS BUS
Secondary EMER BAT BUS
RMU #2 Primary
R MAIN AV BUS
Secondary R ESS BUS
RMU #1 and RMU #2 primary and secondary
circuit breakers are located in the COMMU-
NICATIONS group of circuit breakers on the
respective side. The RMU #2 primary power
is the only power source affected by the avion-
ics master switch.
FMS RADIO TUNING OPERATION
If the optional FMS is installed, the FMS in-
terfaces with the RMUs for radio tuning. The
FMS has a radio tuning page that can be used
t o c o n t r o l V H F C O M , NAV, A D F a n d
transponder codes. If it is suspected that the
FMS is interfering with com/nav radio tuning,
an “FMS ENABLE/DISABLE” selection on
the RMU NAV memory page can be toggled
with the adjacent line select key (Figure 16-
11). The “DISABLE” selection will prevent
tuning any of the radios through the FMS
CDU.
When the FMS is used to change a radio fre-
quency, the RMU will respond by tuning the
frequency and displaying it in the applicable
RMU window. In order to minimize confu-
sion to the pilots, the RMU will change the
color of the active frequency whenever a
change is made that was not generated locally
at the affected RMU. An RMU frequency that
is tuned from the CDH, x-side RMU, or FMS
will be yellow, and a frequency that is auto-
tuned by the FMS will be magenta. That color
will remain until it is changed by the local
(RMU) tuning action.
L E A R J E T 4 5
P I L O T T R A I N I N G M A N U A L
16-25
FOR TRAINING PURPOSES ONLY
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