Specs Blamed for Boeing 787 Fastener Problems

Jason Sandefur

The latest fastener problem on Boeing’s Dreamliner 787 has been traced to an engineering error made at the company’s facility in Everett, WA, the Seattle Times reports. The bolts at the center of the problem were used inside the fuselage to fasten titanium structure to carbon-fiber-reinforced plastic composite.
Boeing’s instructions for fastening titanium to composite “bewildered mechanics,” reports Dominic Gates of the Times.
“Several specifications from Boeing provided ambiguous instructions and measurements that led mechanics to cut too shallowly the tops of the holes they were drilling,” Gates writes.
The fastener issue has “rippled from Everett to suppliers around the world.”
Since the location of all the fasteners is not certain, mechanics have to re-inspect the airplane from nose to tail. One unnamed 787 mechanic described quality-control inspectors “crawling through” the first two airplanes in the assembly bay “ripping all the systems out, everything that’s in the way.”
A pressurization test revealed a small gap under the heads of thousands of fasteners inside the fuselage.
The specification that mechanics consult for precise instructions made proper installation impossible. “The regular spec document for installing fasteners sent the mechanic to another spec if composite plastic was being drilled,” Gates writes. “This spec then correctly sent the mechanic back to the first if the fastener head was on the titanium side, as in this case.”
“But a sub-specification that supposedly superseded the second spec contradicted the main spec with a table containing different and inaccurate measurements.”
The news comes as Boeing’s fastener problems continue to spread. Boeing confirmed it is working to replace more uncoated nutplates that lack a cadmium coating on its widebody jets 747s, 767s and 777s.
About 30% of the nutplates need to be replaced on nearly four hundred 737s delivered after August 2007.
The nutplates — reportedly made by one of three Boeing-approved suppliers to Witchita, KS-based Sprit Aerosystems — lack a cadmium coating that would help prevent corrosion on adjoining aluminum parts. Each 737 contains 3,000 to 4,000 nutplates. �2008 FastenerNews.com