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Delamination prompts Boeing to inspect 787 fleet
Boeing again faces a manufacturing quality issue, requiring inspections and repairs of its 787 fleet. Structural stiffeners were found to be improperly joined to the composite skin in the aft sections of the aircraft, causing parts of the aircraft's carbon fibre structure to delaminate, confirms the airframer. "Boeing has found that incorrect shimming was performed on support structure on the aft fuselage on certain airplanes in our facility in Everett, [Washington]," said the… (www.flightglobal.com) Ещё...
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Like the A380, it is completly new, and whether we like it or not, you cannot possibly think of everything. The main thing is that there is a fast and positive reaction when things are discovered.
You see the prblem is that an aircraft skin can have a temp variation of 90C within a normal cycle .. that is the big hurdle with the new technology...expansion/contraction stress and strain.
Is that the problem? Because I thought that the article said that the problem was incorrect assembly, and didn't mention temperature variations as a cause.
What I read I put in context with my own experience. The up shot was delamination and that means peeling off...bit like plywood when the glue fails. The parts move and are unstable. When they talk of shimming they mean stiffness of that part of the assembly..they are seeking to add mass to reduce movement. The outer skin of an airliner must expand and contract in a predictable way..that is what they are chasing here...stablility.
However unlike wood the new composites are not flexible so they tend to shatter especially when they are cold. With any rigid structure like the new composites it has a certain inherent frequncy at which the structure will shatter. In effect it is a super cooled liquid the same as glass. Minor hiccups such as experienced by Boeing are accepted as normal. The fact that this was identified as a manufacturing flsw bodes well...it means that the Boeing design is sound. If you compare this fault the recent cracking within the wing of the A380 which was an unforseen load..frequent heavy landings cracking the alu L brackets.... it is clear that the new materials pose different challenges to engineers. The essential idea to take away from this event is that the new materials are brittle, and the colder the temperature the more brittle the material.
Most of what was done on this aircraft from reports within said most of what was done had not been tried to this degree before so watch for falling fiberglass or ever what they want to call it.
