Garmin 500W Series, Instructions Manual

Page: 16 / 23

500W Series 190-01226-03 Rev. 5
Instructions for Continued Airworthiness Bell 206B Page 16 of 23
Alert Text Possible Cause Solution
GDL 88 ADS-B transmit
has failed

The GDL 88 is not able to transmit an
ADS-B message due to a failure with
the GDL 88 system or antenna(s)

Refer to the GDL 84H/88H
STC Installation Manual
GDL 88 ADS-B is not
transmitting position

The GDL 88 has detected a position
input fault

Refer to the GDL 84H/88H
STC Installation Manual
GDL 88 ADS-B fault -
Check GDL 88 Status
Page

The GDL 88 has detected an
equipment fault

Check the GDL 88 status
page in Aux mode

Refer to the GDL 84H/88H
STC Installation Manual
GPS is not responding
– check GPS antenna
(main software version
3.20 and later).

GPS antenna cable is shorted

Verify that the center
conductor is not shorted to the
braid in the coaxial cable.

Internal system-to-system
communication between the main
processor and the GPS receiver has
failed. Operational status of the GPS
receiver is unknown.

Contact Garmin technical
support.
GPS needs service

The 500W Series unit has detected a
failure in its GPS receiver.

Contact Garmin technical
support.
GTN transfer canceled,
version mismatch

The protocol version or database
version don’t match between the GTN
and GNS units

Load the most current cycles
of the navigation database to
each unit
Insufficient Terrain
Database Resolution

The installed terrain database does
not have sufficient resolution to
support HTAWS

Load a 6 arc second terrain
database
Large magnetic
variance

A valid value of magnetic variation is
not available for this location.

Verify all course angles

Contact Garmin technical
support.
Loss of integrity —
cross-check NAV

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.

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.
Low Battery - Unit
Needs Service

Time data may have been lost due to
a memory battery failure.

Contact Garmin technical
support.
MAIN processor
requires service

The 500W Series unit has detected a
failure in the main system processor.

Contact Garmin technical
support.