"“We have lent a huge amount of money to the U.S. Of course we are concerned about the safety of our assets. To be honest, I am definitely a little worried.” "

Chinese premier Wen Jiabao 12th March 2009

""We have a financial system that is run by private shareholders, managed by private institutions, and we'd like to do our best to preserve that system."

Timothy Geithner US Secretary of the Treasury, previously President of the Federal Reserve Bank of New York.1/3/2009

Thursday, November 20, 2008

Boeing 787 Dreamliner - Some Good news and some very, very , very bad news

The 100% composite wing box on the Boeing 787 Dreamliner, weighing 55,000 , the first ever for a Boeing commercial airplane has caused caused considerable problems and stalled development whilst it has been redesigned. It was designed and built by a joint team of Boeing, Mitsubishi Heavy Industries and Fuji Heavy Industries.

Full scale destructive testing has just been completed , a major milestone in certification - albeit some 2 years behind schedule.

This also provides a verification of the simulations and analytical methods used to calculate the loads the structure will have to carry. (video of test available here)

The wing box is a cantilevered beam that carries the wing to the fuselage and supports leading- and trailing-edge devices, control surfaces, engines and landing gear. The test piece represents a portion of the wing section that begins at about the center of the airplane and stops at approximately one-half of the span of the wing -- approximately 50 feet (15.2 meters). The piece measures approximately 18 feet (5.5 meters) at its widest point.The upper and lower surface panels and the spars of the wing are made entirely of the same composite material being used on the fuselage.

Each main wing rib is however a monolithic aluminum structures, each machined from a single piece of aluminum plate.

Certification requires, the wings must withstand loads up to 1.5 times, or 150 percent, of the highest aerodynamic load that the jet could ever be expected to see in the entire lifetime of the 787 fleet.

Structural testing will now have to continue on two full-scale 787 airframes as part of the certification process for the airplane to demonstrate the performance of the structure through multiple lifetimes of normal operational loads and test the structure beyond the points expected to be seen in service.

Fastener problem on Dreamliner due to engineering error at Everett

It has been revealed today that the problems with fasteners - another that has caused major delays , has been identified as an engineering error made in Everett.

Thousands of fasteners on every Dreamliner used inside the fuselage to fasten titanium structure to carbon-fiber-reinforced plastic composite are going to have top be replaced , up to 8,000 on each of the first down planes under construction.

The problems emerged with the fasteners emerged after a pressurization test in October .The problem arose only on structures installed inside the fuselage shell — such as the floor grid — where titanium was fastened to the composite. What this means in terms of further delay is not yet known. It will certainly delay the first flight even further than previously planned.

A whole series of strict Boeing specifications governs installation of fasteners, depending on the materials being joined together. It appears that with these fasteners , 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.

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.

Whilst not a safety problem 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. It also reveals a serious lack of quality-control inspection, especially early in the program.

Apparently , the specification that mechanics consult for precise instructions made the job impossible. With these specific fasteners they wouldn'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.

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.

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.

787 partners under pressure - and hurting

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.

Vought next door in Charleston is less affected by the problem than other 787 partners. Only the rear fuselages of seven airplanes — No. 5 through No. 11 — have to be reworked which will take about a week per airplane to remove and reinstall all the fasteners - involving replacing fewer than 2,000 fasteners per airplane on its 38-foot-long sections.

Boeing is expected to announce a new Dreamliner delivery schedule incorporating both the strike delay and the fastener fix ... some time real soon now.

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