View Full Version : A320, DC ESS BUS FAULT and HYD B

4th Sep 2012, 13:06
Hello everybody,

I noticed that when an DC ESS BUS FAULT occurs on A320 you are losing the blue hydraulic system because your electric blue pump is connect to this bus.

I am wondering why the procedure described in the FCOMs do not say to extend the RAT, I don't understand the purpose of continue to fly with only 2 hydraulic systems when you are able to recovered the third one with the RAT.

Thank you for answers


4th Sep 2012, 13:11
This puts you into EMER ELEC, as far as I remember.....

4th Sep 2012, 13:15
Hi Aurel,
I think airbus simply thinks there is no need to deploy the RAT because redundancy is still given(Green and Yellow Hyd).Also the RAT is limited to some certain aspect too,like minimum airspeed e.g.

4th Sep 2012, 13:20
If your fault clears and you regain the bus you would no longer need the RAT.

Unfortunately, once deployed you cannot retract a RAT, so it would sit in the airflow causing a drag penalty and using up operating hours for no benefit.