James, I know of no major structural repairs on BUFF. Depending how you define 'major,' frequently the AF answer is to park them when there are things like wing box issues. Just too expensive to fix. There has been cash spent upgrading capacity and systems, not sure if that is what you meant.

I work with some folks who will probably know the answers and will ask them later in week when I see them.

Out of curiosity, why the concern?