190-02246-11
GI 275 Part 23 AML STC Maintenance Manual
Rev. 1
Page 4-24
Figure 4-17 AHRS Alert Message Troubleshooting
AHRS Fault
Messages
If fault persists,
contact Garmin.
AHRS <1/2/3>
MISSING
-or-
AHRS MISSING
Cause
Multiple AHRS are
configured in the
system and the
reported AHRS is not
detected
Corrective
Action
Ensure the missing
AHRS is powered
Ensure the missing
AHRS configuration
is correct
Verify wiring is
correct
AHRS <1/2/3>
MISCOMPARE
-or- AHRS
MISCOMPARE
Cause
Multiple AHRS are configured, a
reported AHRS heading
difference of 6 degrees or more
is detected
Maintenance
Log Message
Maintenance
Log Message
AHRS <1/2/3> does not
match other senosrs
All AHRS sensors do not
match
AHRS <1/2/3> data is
missing and cannot be
compared
Not enough AHRS sensors
to perform a comparison
Multiple AHRS are configured, a
reported AHRS pitch or roll of
5 degrees or more is detected
Corrective
Action
Determine if pitch,
roll or heading is out
of tolerance
Heading out of
tolerance:
perform
magnetic calibration
on all configured
heading sources
AHRS <1/2/3>:
Magnetic model
outdated
Cause
Maintenance
Log Message
Corrective
Action
Pitch or roll out of
tolerance:
perform
pitch-roll offset
calibration on all
configured sources
AHRS <1/2/3>
Magnetic Model
out of date
Magnetic model is
out of date
Update the IGRF
Magnetic Field
Model
Cause
Maintenance
Log Message
Corrective
Action
AHRS <1/2/3> not
receiving GPS
aiding
AHRS <1/2/3> not
receiving GPS
aiding
Not receiving GPS
data from a
configured GPS
source
Verify GPS
configurations
Verify GPS antenna has a
clear view of the sky and
GPS source has a valid fix
Verify connections
and wiring
AHRS <1/2/3>
reports service
required
Cause
Corrective
Action
Service required
Cause
Maintenance
Log Message
Corrective
Action
<AHRS>
configuration does
not match what the
unit expected
AHRS LRU is not
configured correctly
Verify AHRS
configuration
settings
Bad AHRS calibration
No data from ADC
Ensure ADC is
powered on
Perform AHRS
calibration
Verify connections
and wiring
Magnetic variance
inaccurate
Maintenance
Log Message
ADB and IOP
packet magnetic
variances differ
Cause
Aviation database
out-of-date on
GI 275 / Navigator
Corrective
Action
Ensure aviation
database is up-to-
date on GI 275 and
configured navigator
Magnetic variance
unavailable
Maintenance
Log Message
ADB is unavailable
for magnetic
variance
Cause
Aviation database is missing
Navigator / GPS source
unavailable
Corrective
Action
Ensure aviation
database is loaded
and up-to-date
Verify GPS source
online
