Instruction Manual

Instructions for Continued Airworthiness 190-00792-12 Rev 1
for the Garmin G500H Installation in Eurocopter AS350 Page 67 of 80
Problem Cause Solution
(valid data is being received
on the 429 input port as
shown on the GDU 620 PORT
MONITORING page)
Wrong device is connected to
port on GDU 620.
Use correct ports (refer to interconnect
details).
Data is not being received
from an ARINC 429 device.
(no data is being received on
the 429 input port as shown
on the GDU 620 PORT
MONITORING page)
On the transmitting LRU, the
ARINC 429 transmitter speed is
not set correctly.
Set the ARINC 429 transmitter speed to
correct speed.
Wiring is not correct.
Check for continuity/shorts and correct as
required.
Attitude and heading on
GDU 620 red ‘X’ / GRS 77H
resets during air data ground
testing.
Attitude and heading
errors/resets are possible if the
air data tests are conducted
indoors without a good GPS
signal. With marginal or no GPS
signals present, sudden changes
in airspeed caused by using a
pressure tester may result in
attitude and heading errors and
possibly cause the GRS 77H to
reset. This occurs because the
artificial changes in airspeed
cause disagreement with the
other sensor measurements
internal to the GRS 77H. This
sensor disagreement will not
occur in the normal conditions of
flight.
This is expected behavior and no
troubleshooting is required if this occurs.
To reduce the chances of inducing
attitude and heading errors/resets while
conducting the air data tests, ensure that
the G500H is receiving good GPS signals.
Heading red ‘X’ during air
data ground testing
Invalidation of heading is possible
if the air data tests are conducted
indoors, due to typical magnetic
anomalies, even with a good GPS
signal.
This is expected behavior and no
troubleshooting is required if this occurs.
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