Boeing's strategy with the 787 has been to make a light, efficient, smaller-scale jet to appeal to carriers concerned about costs. So among the other innovations, the company is making the wings out of carbon-fiber composite instead of metal. No one's ever really tried that before, so testing is critical. Here's the June 25 Aviation Week and Space Technology on that subject:Boeing has completed static testing of a three-quarter wingbox, but engineers are still considering whether to limit testing of the full wing to a 150% load limit held for 3 sec. of to continue bending it to see when it breaks. "There's a raging debate within the engineering team to see if we should break it or not," says [787 General Manager Mike] Bair.
Breaking it isn't necessary for certification, but Bair says the wing is so strong and flexible that there's been talk that maybe it could be bend far enough for the wingtips to touch above the fuselage—or come quite close.
That's a tremendous technical achievement, certainly. Notwithstanding, if I'm ever on one of these marvels and I see that happening outside my window, the first thought I have will not be "Wow, those carbon-fiber composite wings are incredibly resilient and demonstrate amazing load-bearing capacities as compared with older, less efficient metal aircraft wings."