Boeing just released its third in an ongoing series of 787 milestone videos on its website. The latest chronicles the completion of destructive testing on the 787 test wingbox. The results of will be analyzed and applied to additional testing on the 787 static airframe (ZY997). The final validation of wing strength for FAA certification will be carried out on ZY997 when the wing is bent to apply 150% of maximum loads. Boeing has not yet decided if it plans to break the wings of ZY997. One could speculate that the destruction of the test article helped in determining the extent of debris cleanup that might be required if the test was carried out on ZY997 inside the factory. In January 1995, the Boeing 777 was brought to 154% of maximum loads before it snapped in spectacular fashion.
Breaking the wing is not a requirement for certification, but would help in understanding the overall strength of the wing. If the wing survives well past 150% of maximum loads, it would provide a guide for weight reduction because the wing would be carrying too much structure, as well as assisting in understanding the growth potential for future 787 models.
on November 18, 2008 3:47 PM | Reply
I'm curious at what % load the wingbox actually snapped. While the requirement is for 150%, neither the video nor the press release ever state if the break occurred exactly at 150%, beyond 150%, or perhaps even below that mark.
on November 18, 2008 5:56 PM | Reply
The video on Boeing's site says "beyond 150%", towards the end.
on November 18, 2008 11:08 PM | Reply
Jon, the wing box that was used for this test....does it happen to be the "new" one or the old one (modified) which are in the first 6 airframes? As far as i remember from your posts the wingboxes supplied by Fuji heavy industries were found to be buckling prematurely and hence they went about redesigning it. However the 6 airframes which have the old wingbox will have strengtheners or so attached to them?
on November 19, 2008 10:56 AM | Reply
As far as I know, the wingbox itself wasn't subject to a significant design change. The part in question is the center wing box which connects the wings (which hold the wing boxes) to the fuselage.
As for the status of those fixes on the center wing boxes on 1-6, I'm not sure. I'll try and find out though.
Jon
on November 20, 2008 1:15 AM | Reply
Thanks for the clarification Jon! My mistake i confused the centre wingbox with the wing boxes! Always look fwd to your updates...Keep up the good work. :)