These are just two lessons learned from over the years.
Theoretically, any AGM failure pulls AGM #3 and creates a red "X" on DU #3. I've had this happen where the autoreversion didn't happen. As it turns out, the reversion mode is within the AGM itself, so if the AGM fails completely it may not revert. If this happens to you, you cannot MEL the AGM, but you can swap them, as we did here.
If you have to fly with a red "X" on the tube, simply turn the brightness to full dim. The screen will go blank, except at night when you can see a dim red "X" if you look hard enough.
Most of the problems we have with the G450 FMS are pilot programming errors. Most, but not all. If you stumble upon a computer programmer error with your FMS, downloading the FMS debug file might give those programmers the information they need. Try to record everything you have pertinent to what you and the FMS were doing prior to the problem, how the problem manifested itself, and how you were (or were not) able to resolve the issue. Once you get on the ground, download the debug file as follows.
On the MCDU, press the NAV key to bring up NAV INDEX 1/2. Press the NEXT key to bring up NAV INDEX 2/2.
Select MAINTENANCE (LSK 2R) to access the FMS MAINTENANCE 1/3 page.
Press the NEXT key to access the FMS MAINTENANCE 2/3 page.
Select SETUP (LSK 6L) to access the FMS SETUP 1/1 page.
Select ENGR DATA (LSK 2R) to access the ENGINEERING DATA 1/1 page.
Select DEBUG (LSK 1L) to access the DEBUG MONITOR CNTRL 1/1 page.
Before selecting CTL D (LSK 4L) ensure PCMCIA 2, not PCMCIA 1 is selected as the storage device by selected OR (LSK 5R).
Select CTL D (LSK 4L) to start the Control-D file capture process.
Repeat this process for all three MCDUs.
This will send FMS Debug Data to the PCMCIA card in the DMU. Retrieve the data by inserting the PCMCIA card to a compatible computer.
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