System Maintenance Manual

G1000/GFC700 System Maintenance Manual – C90A/C90GT/C90GTi King Air Page 5-75
190-00682-01 Revision G
NOTE
It is important that the “time equals zero” moment corresponds with the moment the PFD
first displays the blinking TEST COMPLETE? message.
Figure 5-8. Magnetometer Interference Test Complete
7. The operator should carry out the actions called for in the prepared test sequence.
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.
8. When the operator has completed the actions specified in the test sequence, press the ENTER
button to indicate that the process is complete. When this is done, the TEST COMPLETE field
stops blinking.
9. 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. When the magnetometer interference test fails, record the
three magnetometer maximum deviation values and their corresponding timestamps. Any
maximum deviation value greater than 2.5 milliGauss indicates a problem that must be resolved.
Compare the corresponding timestamps with the prepared test sequence to identify which action
produced the problem. Contact Garmin for assistance in resolving the problem.
NOTE
Two common reasons for a failed magnetometer interference test are: 1) new equipment
is installed in close proximity to the GMU 44 magnetometer, and 2) 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.
10. Press the ENT key on the PFD to conclude this procedure.