The idea of cutting a piece out of a complete barrel for a repair is nowhere near as extreme as it is being painted. First, the barrel itself is not stuffed; what goes into it is probably far more expensive than the empty barrel. And that is the only way of getting the exact repair piece, and is much less expensive than making a special mold to fabricate it. Expect Airbus to do the same should an A350 ever need a similar repair. Boeing could keep the remainder of the barrel in case another 787 needs a similar repair in a different spot, but they probably consider that to be unlikely and so won’t keep it.

The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler