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?
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@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?
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I'm betting you don't like losing the checklist on the MFD. Here's what my checklist is for external power startup after the engines are fired up:
Gen ties Open
External power off
Select R Gen volts
R Generator reset and then on (that brings the MFD back online because it's powered from the right side)
MFD - RCL button twice (gets you back to the checklist)
Select L Gen volts
L Generator reset and then on
Gen ties norm
External power disconnectthat gets your checklist back up and running as quickly as possible. Waiting to disconnect shouldn't be an issue with the external power source turned off (I think
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@ProfCrash Tried manually closing your Bus Ties (switch on pedestal) before disconnect?
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Generally no, When I flew the king air we kept the battery off the buses because it was a huge drain to try and power avionics and start the engines, plus we didnt want to risk voltage transients cutting out the inverters in the event the battery was weaker than anticipated.
