Alert Text
GDL 88 ADS-B transmit
has failed
GDL 88 ADS-B is not
transmitting position
GDL 88 ADS-B fault -
Check GDL 88 Status
Page
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
500W Series
Instructions for Continued Airworthiness Bell 206B
Possible Cause
The GDL 88 is not able to transmit an
ADS-B message due to a failure with
the GDL 88 system or antenna(s)
The GDL 88 has detected a position
input fault
The GDL 88 has detected an
equipment fault
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 500W 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 500W Series unit has detected a
failure in the main system processor.
Solution
Refer to the GDL 84H/88H
STC Installation Manual
Refer to the GDL 84H/88H
STC Installation Manual
Check the GDL 88 status
page in Aux mode
Refer to the GDL 84H/88H
STC Installation Manual
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.
190-01226-03 Rev. 5
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