Question for fellow EMBRAER E-Jets pilots...

[Butters Stotch]

Hello guys! Hope everyone is fine and flying safe.
I have a tech question for the E-jets pilots out there (sorry if it is stupid):

While performing the "dual engine failure checklist", with no engines auto-relighted, we come to a point that, whether you are on RAT power (only essential / hot buses powered) or APU power (all buses powered), you're supposed to turn the fuel Xfeed to low 1. I can't figure out why is that. Does anyone know?

I bet it probably has something with the fuel pumps and engine ignitors, but i haven't came to a conclusion yet. Can you help me?

Thanks a lot and congrats for such a high level forum!

 

[Autothrust Blue]

Hello guys! Hope everyone is fine and flying safe.
I have a tech question for the E-jets pilots out there (sorry if it is stupid):

While performing the "dual engine failure checklist", with no engines auto-relighted, we come to a point that, whether you are on RAT power (only essential / hot buses powered) or APU power (all buses powered), you're supposed to turn the fuel Xfeed to low 1. I can't figure out why is that. Does anyone know?

I bet it probably has something with the fuel pumps and engine ignitors, but i haven't came to a conclusion yet. Can you help me?

Thanks a lot and congrats for such a high level forum!

I'm not typed on the 170, but might this be somehow related to which fuel pumps have power when all the lights in the house go out?

 

[NC_BE300]

From what I gather and have read...this is what i see....

Assuming loss of both engines, and running RAT power only....
The RAT is now powering the AC Essential Bus.....which powers the AC Standby Bus (on that bus is the A Ignition, Hyd Pump 3A, and the #2 AC fuel pump)

So im going with its just trying to make sure fuel/fuel pump available to something your trying to start.....be it either the APU or engine.

Anyone else feel free to chime in.

 

[Butters Stotch]

Thanks for your reply guys.

NC_BE, it´s probably about the #2 AC fuel pump as you said. I believe that turning the Xfeed to low 1, you get that AC started, raising the fuel pressure on the fuel lines...

That´s what i believe in!