I was reading Why do many GA aircraft not have a "Both" fuel selector? and voretaq7's excellent answer got me to thinking.
He cites the regulations noting that the plane must only draw fuel from one tank or have a method for preventing air from entering the fuel lines. However all his examples assume gravity in a somewhat constant direction.
What do you do when this is not the case? For example in a barrel roll do you set the fuel selector for the wing going up first? Does it depend on the plane? Do planes in air shows have special fuel systems?
How does this regulation apply to aerobatic aircraft, and how is the regulation satisfied for such aircraft?