B747-8: Hydraulic Demand Pumps and Main tank fuel pumps powered by DC?

[RandomPerson8008]

Hello,

In the 747-8 flight training device (FTD), a DC bus 2 failure induces the loss of the #2 electrically driven hydraulic demand pump and main tank fuel pumps #1 fwd and #4 fwd, among other problems more typically expected from a DC failure. We are training this failure because it occurred in a real aircraft a few years ago.

I was under the impression that motor-pumps were typically AC powered when possible due to the inherent benefits of using AC for high output applications (weight, size).

Without access to an AMM, does anyone have a list of items powered by the DC electrical system? I realize it would be quite a long list, but I am surprised to see this failure resulting in the loss of a demand pump and fuel pumps. There is also a #2 utility bus failure associated with the loss of the #2 DC bus in the FTD, which also surprises me since I thought the utility buses and ELCU's were part of the AC electrical system.

Could these fuel pumps and hyd dem, pump be, in fact DC powered, or is there some other explanation?

To summarize:

Are the #2 & #3 hydrualic demand pumps and some main tank fuel pumps (aside from the dedicated APU DC pump) powered by the DC electrical system?
If not, why would these items fail during a DC bus failure?


Thanks!