External power startup - FMS-checklist items order
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When following the FMS checklist for startup with external power connection, the external power switch - OFF and external power source - REMOVE comes before the genererators reset then ON. If I switch external power off before generators ON, I loose power to the aircraft. It seems like I need to turn generators on before disconnecting EXT power. Even if battery switch is on of course.
Another thing, is it possible to turn on EICAS display with battery switch off irl? It seems like that is possible (at least when I did my last shut down today)
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Generally speaking, it's bad practice to bring the generators online before disconnecting the GPU, because this might cause unstable voltage that may damage electronics, burn out bus shunts, or might trip the GPU's overvoltage protection. I know this to be true for King Air's so I assume that it is for Starship too.
The answer to your second question is actually related to your first. The EICAS has its own battery backup so that it may operate uninterrupted and with a clean voltage supply during the startup procedure. You can see this on the Live Electrical Schematic page of the Tablet Interface, and play with the logic by pulling the circuit breakers on the bottom left row of the copilot's circuit breaker panel.
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Generally speaking, it's bad practice to bring the generators online before disconnecting the GPU, because this might cause unstable voltage that may damage electronics, burn out bus shunts, or might trip the GPU's overvoltage protection. I know this to be true for King Air's so I assume that it is for Starship too.
The answer to your second question is actually related to your first. The EICAS has its own battery backup so that it may operate uninterrupted and with a clean voltage supply during the startup procedure. You can see this on the Live Electrical Schematic page of the Tablet Interface, and play with the logic by pulling the circuit breakers on the bottom left row of the copilot's circuit breaker panel.
@Black-Square Ok, then the GPU disconnect before switching generators ON make sense. But is it correct that I lose the the power when I switch the ext pwr off after starting the engines?
