On this question for the A320 after dual engine failure it says:
When the hydraulic power is lost, the right aileron is lost, and is in the upfloat position.
Why would this affect only the right aileron?
Assuming it's zero fuel dual engine failure with no chance of powering up the APU, the plane is left with the Ram Air Turbine (RAT).
1. The emergency electrical configuration only powers ELAC 1, one of the two units that control the ailerons, and ELAC 2 is lost (see below).
2. The RAT powers only the Blue hydraulic system.
Add those two conditions with the color coded schematic below:
And the right aileron will not be powered. The same schematic can be found in the FCOM under Flight Controls > General > Architecture (27-10-20), the one above is clearer though.