A320 series ETOPS
Tried to to a search on this subject but little came up.
I am curious about Airbus 318/319/320/321 ETOPS certification, I know that they are approved for 180 min, but what I want to know is in what way systems redundancy is provided, mainly for hydraulics and electrics. Is there a Hydraulic Motor Generator, or a Ram Air Turbine? If not how is redundancy achieved? Is the APU supposed to start even when "cold-soaked"
Thanks,