B777 backup generators
 

Can back up generators(B777) produce electric while the both engines fails due to empty fuel tanks?

Lets say during flight you lost both engines due to out of fuel, but the engines are still turning because of windmilling... Can back up generators produce electricity?

In short, no. The backup generators are engine driven, 'frequency wild', thus rely on engines operating in order to work.

If you lose both engines, the ram-air turbine will automatically deploy.

It will provide hydraulics to the essentials first, and if it has spare capacity, will provide electrical power to the Captains flight instruments, and through another bus, the FO flight instruments.

There is a delay in receiving electrical power, however. All screens will blank, the RAT will get to work, and a minute or so later, some electrics will be restored as per above.

Hope this helps..

From my point of view, as long as there is a N2 rotation, the backup generator will be driven thru the IDG and hence delivering power to the xfer busses.

I am really glad I never found out the answer to that question. 😁