Boeing 787 fastener problems caused by Boeing engineers
Boeing's 787 Dreamliner fastener glitch, which now has mechanics finding and replacing thousands of fasteners on every one of the new planes, was caused by a Boeing engineering error made in Everett.
Seattle Times aerospace reporter
The Boeing 787 Dreamliner's latest problem can't be blamed on the Machinists strike. Nor is it the fault of inexperienced mechanics at Boeing's far-flung suppliers.
The big glitch that now has mechanics finding and replacing thousands of fasteners on every Dreamliner was caused by a Boeing engineering error made in Everett.
The bolts in question were used inside the fuselage to fasten titanium structure to carbon-fiber-reinforced plastic composite, and the problem emerged after a pressurization test in October.
The fix could require replacing up to 8,000 of the fasteners on each of the first dozen planes that are in various stages of completion.
It's unclear how much extra delay this will cause to the Dreamliner program. Some suppliers can do the additional work during the production delay due to the strike. But in Everett, it will likely delay first flight even further than previously planned.
A whole series of Boeing specifications governs installation of fasteners, depending on the materials being joined together. In this case, the instructions for fastening titanium to composite bewildered mechanics.
An operations manager at a Dreamliner supplier plant said he examined the specifications closely with an experienced design engineer after the problem was discovered and realized the mechanics were not at fault.
Several specifications from Boeing provided ambiguous instructions and measurements that led mechanics to cut too shallowly the tops of the holes they were drilling.
"If I'm struggling and a 25-year design engineer is struggling, how can you expect a mechanic to understand this?" said the manager, who asked not to be identified to avoid conflict with Boeing.
Boeing discovered the fastener problem last month, in the midst of the strike. A pressurization test on one of the completed Dreamliners revealed a small gap under the heads of thousands of fasteners inside the fuselage.
The problem arose only on structures installed inside the fuselage shell — such as the floor grid — where titanium was fastened to the composite.
It isn't a safety threat, says Boeing, but it potentially could reduce the airframe's durability. Boeing and its partners must fix it on all the planes now in Everett and on all the partially completed sections at supplier plants worldwide.
On a home-repair project, drilling a hole may be a hit-or-miss affair. On an airplane program, getting it right is more crucial.
In this case, the specification that mechanics consult for precise instructions made the job impossible.
The fastener in question won't sit properly in the hole unless the top of the hole is widened to accommodate a bevel, a curved join between the head and the shank of the fastener. The mechanic has to prepare the hole by cutting it wider at the top, first consulting a specification to find out exactly how much to cut.
But the documents were confusing. The regular spec document for installing fasteners sent the mechanic to another spec if composite plastic was being drilled. 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. A separate document clouded the instructions further.
"I don't think it should be pushed on the inexperience of the mechanics," said Joy Romero, vice president of Vought's 787 program and head of the Charleston, S.C., plant where the rear fuselage sections are assembled. "It's more about the clarity of the specifications and the confusion of the specifications."
The specifications were prepared in Everett by Boeing engineering staff and were supposed to be translated by Boeing planners into easily followed instructions.
Boeing acknowledges that the instructions were confusing and says they are being rewritten.
Fixing the mess means undoing much interior installation work already completed.
A person working on the 787 in Everett said the insulation blankets that lined the walls of Dreamliner No. 1 in Everett were removed to allow access to the fasteners.
The location of all the fasteners is not certain, so "they have to reinspect the airplane from nose to tail," he said.
The fastener woes revealed a serious lack of quality-control inspection, especially early in the program, he said.
Quality-control inspectors are "crawling through" the first two airplanes in the assembly bay "ripping all the systems out, everything that's in the way," said an Everett 787 mechanic.
Hurting 787 partners
The fastener issue has rippled from Everett to suppliers around the world.
Romero said Vought is less affected by the problem than other 787 partners. She said only the rear fuselages of seven airplanes — No. 5 through No. 11 — have to be reworked.
It'll take a small team about a week per airplane to remove and reinstall all the fasteners, said Romero.
Vought believes it can complete the fastener fix during a production hiatus there caused by the Machinists strike at Boeing's Puget Sound-area factories.
"We'll be able to work fasteners at the same time" as other required changes, Romero said.
A person close to the factory operations at Vought estimated mechanics will probably have to replace fewer than 2,000 fasteners per airplane on its 38-foot-long sections.
Next door to Vought in Charleston, at the Global Aeronautica plant, the fastener problem is "much bigger," according to people with knowledge of the factory who asked for anonymity because Boeing had not authorized them to speak publicly.
Global Aeronautica, a joint venture between Boeing and its Italian partner Alenia, assembles the 84-foot-long central fuselage from sections that arrive partly complete from Italy and Japan.
At the Spirit AeroSystems plant in Wichita, Kan., a person familiar with the situation said the problem affects up to 3,000 fasteners per plane.
A person who works on the Dreamliner program in Everett cited an internal estimate that the total number of fasteners to be replaced per airplane is about 8,000.
The Wall Street Journal reported Wednesday that though the Machinists strike lasted eight weeks, Boeing will push out scheduled deliveries of all its jet programs as much as 10 weeks as it plans an orderly ramp-up of production.
Before the end of the year, Boeing is expected to announce a new Dreamliner delivery schedule incorporating both the strike delay and the fastener fix.
Dominic Gates: 206-464-2963 or email@example.com
Copyright © 2008 The Seattle Times Company
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