Why the Voltage Drop during ramp start?

[RichardG]

When I switch from the APU generator to the engine generators, I get a voltage drop that resets the CICU, IFFCC and the CDU. So its pretty much pointless to turn these systems on until both engine generators are running.

 

Specifically, I just flip the engine generator switches on while the apu generator is running. Thats when the systems reset.

[Nate--IRL--]

Known Bug.

 

Nate

[andysim]

just do what I do and ask for ground power before any other step. I do this in multiplayer so I can get the system alighing whilst I am setting up the aircraft.

[airdog]

Not sure if this applies to the A10C but in older aircraft this is the norm(the power dip). Usually important systems are not powered up until the aircraft is running on one of it's engine driven generators. Just to preclude problems with power transfer between the aircraft main bus and the APU or ground power busses.

Heck most of us remember or have seen on commercial aircraft the flash or dimming of the cabin lights in commercial aircraft right after engine start...that is due to the busses tranferring from ground/apu bus to the main electrical busses.

The MD-11 was one of the first large commercial aircraft to introduce what they call the "No break power transfer" or NBPT and it all but eliminated the voltage drop when systems were switched between different power sources(ground,apu,main) thus allowing systems(INS and other avionics) to stay powered up during the power transfer and not losing information or sync/alignments. But even with this system the cockpit MFD's still would get the dreaded red X occasionally.