Garmin 400W Series Instructions Manual page 20

Alert Text
GPS is not responding –
check GPS antenna (main
software version 3.20 and
later).
GPS needs service
GTN transfer canceled,
version mismatch
Insufficient Terrain Database
Resolution
Large magnetic variance
Loss of integrity — cross-
check NAV
Low Battery - Unit Needs
Service
MAIN processor requires
service
No altitude input is being
received
No basemap data available
Not receiving input data on
429 Channel #1 or #2
400W Series
Instructions for Continued Airworthiness Bell 407
Possible Cause
 GPS antenna cable is shorted
 Internal system-to-system
communication between the main
processor and the GPS receiver has
failed. Operational status of the GPS
receiver is unknown.
 The 400W Series unit has detected a
failure in its GPS receiver.
 The protocol version or database
version don't match between the
GTN and GNS units
 The installed terrain database does
not have sufficient resolution to
support HTAWS
 A valid value of magnetic variation is
not available for this location.
 Verify all course angles
 Improper antenna installation or coax
routing
 Antenna shaded from satellites
 RF interference at 1575.42 MHz from
VHF COM.
 Time data may have been lost due to
a memory battery failure.
 The 400W Series unit has detected a
failure in the main system processor.
 No altitude data is being received
from RS-232 (Serializer: Icarus,
Rosetta or Shadin) or grey code
inputs.
 The 400W Series unit has detected a
failure in the built-in basemap (land
data) memory. Land data does not
appear on the Map Page. Other unit
functions continue to work normally.
 No data has been received on the
ARINC 429 channel #1 connection
for a period exceeding five seconds.
Solution
 Verify that the center conductor
is not shorted to the braid in the
coaxial cable.
 Contact Garmin technical
support.
 Contact Garmin technical
support.
 Load the most current cycles of
the navigation database to each
unit
 Load a 6 arc second terrain
database
 Contact Garmin technical
support.
 Check GPS antenna installation,
connections, and cable routing.
The GPS antenna must be
mounted on the top of the
aircraft.
 Make sure the aircraft is clear of
hangars, buildings, trees, etc.
 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.
 Contact Garmin technical
support.
 Contact Garmin technical
support.
 Refer to Table 2 "RS-232 device
is not communicating with the
400W/420W/430W".
 Contact Garmin technical
support to reload the basemap
data.
 Refer to Table 2 "ARINC 429
device is not receiving data from
the 400W/420W/430W"
190-01226-14 Rev. 3
Page 20 of 26