I get this question every now and then: "On a few occasions, I have, upon turning the main batteries and DU1 on, gotten some really crazy CAS messages. I proceeded to return to a dark cockpit condition to reboot the system. The other day I tried to reboot 3 different times and never could get rid of the erroneous messages. I took the 450 to Gulfstream, and of course, it didn't happen once. Do you have any suggestions for a reboot procedure?"
The reboot takes some learning. For some items a simple power down and restart will suffice. But for others, we found out, it takes at least 12 minutes. Here are some lessons learned.
Get to know what your CAS looks like when you bring up a DU for the APU fire system check. On our aircraft, we have some red, amber, and two blues on the bottom of the first page. That is provided the baggage door is closed and the TROV is open. There could be other reasons, such as low fuel levels. If we ever see fewer blues, meaning there are more reds or ambers, that might mean the airplane didn’t wake up properly and there is no sense starting the APU. We do a quick reboot at that point.
During initial power up, don’t touch anything that is software driven. The only exceptions we make are the clocks, the warning chime cancel, and the warning system inhibit.
If the problem is pretty simple, we try a quick reboot. Shut everything off, shut the APU down, turn the battery switches off and wait for two minutes. We got that time from the early database update manuals which advised two minutes. Then attempt a restart. That often works.
If the issue is complex (more than one system affected) or a quick reboot didn’t work, we do a full reboot. That is simply a reboot with a 12 minute wait for all power off. We got that from a Gulfstream technician about five years ago. He said some of the computers require that much time to power off from internal batteries. We have found this does work when repeated quick reboots have failed. If it doesn’t work, you’ve got other issues.
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