Which bus is normally powered by AC Bus 1?

Which bus is normally powered by AC Bus 1?

• A. AC ESS Bus
• B. AC Battery Bus
• C. APU Bus
• D. Engine Generator Bus

Answer: (A)

AC Bus 1 is connected to the AC Essential Bus in normal operation. This arrangement ensures that the most critical systems—essential avionics and flight-critical equipment—keep power even if other nonessential loads on the second bus are lost. The APU bus and Engine Generator Buses are normally tied to their respective generators, and the AC Battery Bus is used only as a backup in emergency conditions, not as the normal source for the essential loads. So, the AC Essential Bus is the one normally powered by AC Bus 1.

AC Bus 1 is connected to the AC Essential Bus in normal operation. This arrangement ensures that the most critical systems—essential avionics and flight-critical equipment—keep power even if other nonessential loads on the second bus are lost. The APU bus and Engine Generator Buses are normally tied to their respective generators, and the AC Battery Bus is used only as a backup in emergency conditions, not as the normal source for the essential loads. So, the AC Essential Bus is the one normally powered by AC Bus 1.