Yeah, it was airworthy, but they had no way to test the gear, so the flew the whole trip with gear down. Also, he didn't do it intentionally. He got into a turn at high altitude and when he was gona come out of it he decided "meh, what the hell" since he was already half way into the roll why not finish it lol.
No, from the report I've heard by tex himself he did it intentionally. It's called a Chaundelle, pull no more than 1 G in the entire roll.
And whoever said he did it twice, check your facts
