Titanium Fasteners Are Key to Dreamliner Design Fix

A month ago Scott Fancher, who heads Boeing’s Dreamliner program, said the changes required to fix a wing design flaw seemed like no big deal. In a conference call with analysts on June 23, Fancher commented: “The area in question is a series of relatively small areas in the side-of-body join and the various modification options that we are looking at are really quite simple. A few handful of parts at each one of the locations that can be installed on aircraft that are already assembled or aircraft that are currently in production within the production system. So (it’s) a modification that can readily be installed.” Oh, was he wrong.

A new report in the Seattle Times says the required fix is major, cannot be made easily on existing test aircraft and will further postpone the Dreamliner take-off-which is already two years delayed.

The problem is that the original design put too much stress on composite sections of the wing, causing them to delaminate. In one potential solution under study, a U-shaped cut-out will be created in each upper wing-skin stringer. The reshaped stringer ends will then be refastened to a titanium fitting that connects the wing stringers to stringers on the fuselage side of the join.

Stringers are the composite rods that stiffen the inside of the wing or body skin. Boeing executives told Wall Street yesterday that a solution has been identified and will be disclosed at a later date.

Still hanging in the balance is the Design News report that the Dreamliner design is 8 percent overweight-and that’s before the new titanium fasteners are added to improve wing-to-body strength.