400W Series
190-01226-04 Rev. 2
Instructions for Continued Airworthiness Bell 206B
Page 9 of 22
Problem Possible
Cause
Solution
GPS signal levels
drop when avionics
are turned on.
•
Noise interference from other
avionics.
•
Turn all avionics off, then turn on each
piece one at a time to isolate the
source of the interference. Route
GPS cable and locate GPS antenna
away from sources of interference.
•
Improper antenna installation or
coax routing.
•
Check GPS antenna installation,
connections, and cable routing. The
GPS antenna must be mounted on
the top of the aircraft.
•
Antenna shaded from satellites.
•
Make sure the aircraft is clear of
hangars, buildings, trees, etc.
The GPS signal
levels are very low.
•
RF interference at 1575.42 MHz
from VHF COM.
•
Move GPS antenna further from the
COM antenna. Add a 1575.42 MHz
notch filter in COM coax. Fix or
replace the COM. Disconnect the
ELT antenna coax to check for
possible re-radiation.
•
The PTT input is not being
pulled low.
•
Check that the PTT (mic key) input is
pulled low for transmit.
•
No transmit power to the COM.
•
Make sure power input is connected to
the COM 25-pin connector P4002 11
and 12 and ground to P4002 21 and
22.
The 400W Series
unit does not
transmit.
•
The input voltage is too low.
•
Increase input supply voltage to
>12VDC. (>24VDC for 430AW
models)
The sidetone level is
too low or too high.
•
Wrong type of headsets, or level
needs adjustment.
•
If necessary, adjust the sidetone level.
Sidetone adjustment is found on the
COM Setup page.
OBS Resolver won’t
calibrate.
•
Incompatible resolver or
improper connection.
•
Check the resolver specifications and
wiring.
OBS indication on
400W Series unit
does not agree with
OBS setting.
•
400W Series unit resolver input
not calibrated correctly.
•
Resolver has not been
calibrated.
•
Check wiring and calibration.
•
ARINC 429 input port speed not
correct
•
Check ARINC 429 input port speed
setting for port that device is
connected to and verify that the
speed is correct for that device.
400W Series unit is
not receiving
heading from
compass system
(ARINC 429
heading input used)
•
Wiring connections are
incorrect.
•
Check
wiring.
•
400W Series unit does not have
a position or flight plan entered.
•
Acquire GPS position and enter a
flight plan.
Autopilot is not
getting GPSS/Roll
Steering data from
the 400W Series
•
400W Series unit ARINC 429
output not configured correctly.
•
Check ARINC 429 output port setting
for port that autopilot is connected to.
