A320 Dual Engine Fail
 

I have question about A320 dual engine fail.
after APU started, can we use Yellow HYD pump to supply Green and Yellow system. in case yes, can we use auto pilot after that, why airbus not mention about this ?

The output of the yellow elec pump is grossly insufficient to run Y plus via the PTU G. Also not enough to run Y with loads. Numbers were mentioned once here on PPRuNe.

At wind milling speeds, true, there will be actually enough pressure on both Y and G from EDPs. Dual ENG does not give you dual HYD with it. Luckily.

So probably, it is the electrical configuration that does not permit AP use, by design. I.e. on purpose and for some very good reason.

My 2c, cheers.

What is the AP going to do for you with both engines failed ? I think there is a reason Airbus don't mention use of AP in this situation!!

With dual Engine flame out aircaft will be in EMER ELEC alternate law. So no AP. If you remain in it for five minutes then IR2 and IR3 is not supplied for rest of the flight, will stay in alternate law. Even if you start an engine AP will not be available.

What don’t you know, Vilas? :D

I assume those is in the systems description of the FCOM and I overlooked it? I’ll have to do some reading today.

It's all in the books ; specifically this one QRH > ELEC EMER CONFIG Sys Remaining > NAV IR > look at the note.

Thanks for that.

No worries. A lot of info has been rearranged these last few years for cross standardisation purposes, so it is quite common to go and seek pieces of info from time to time and struggling a bit to locate it.

Ummmmm because the training system has produced pilots that are helpless without automation.......