Garmin GSU 75 Series Installation Manual page 60

NOTE
It is important that all actions are carried out in the order and at the precise elapsed time
as specified in the prepared test sequence.
3. When the operator has completed the actions specified in the test sequence, press the ENTER key
to indicate that the process is complete. When this is done, the TEST COMPLETE field stops
blinking.
4. The PFD informs the operator if the installation has passed or failed the magnetometer interference
test. If the test passes, no further action is required for this test.
If the test fails, the installation should be considered unreliable until the source of magnetic
interference is identified and remedied. The magnetometer interference test must be repeated until
passed. Record the three magnetometer maximum deviation values and their corresponding
timestamps from the failed magnetometer interference tests. Compare the corresponding
timestamps with the prepared test sequence to identify which action produced the problem.
Contact Garmin for assistance in resolving the problem.
The acceptable magnetic interference limits are defined as follows according to the system
software part number 006-B1068-00.
Square root of ((Mx/12.0)
Square root of ((Mx/12.0)
Where:
Mx = magnetic interference in X-axis (in milliGauss)
My = magnetic interference in Y-axis (in milliGauss)
Mz = magnetic interference in Z-axis (in milliGauss)
NOTE
Two common reasons for a failed magnetometer interference test are:
a) New equipment is installed in close proximity to the GMU 44 magnetometer
b) An existing or new electronic device has become grounded through the aircraft structure
instead of via the proper ground wire in a twisted shielded pair.
5. Press the ENTER key on the PFD to conclude this procedure.
190-01639-00
Rev. 6
The document reference is online, please check the correspondence between the online documentation and the printed version.
2 2
+ (My/12.0) + (Mz/16.0)
2 2
+ (My/12.0) + (Mz/16.0)
2
) <0.6 for fixed wing configuration
2
) <1.0 for rotor configuration
GSU 75 ADAHRS Installation Manual
Page 5-13
340095