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10 Dec 2009

Boeing’s 787 Dreamliner – Dream of A Thousand Days

Posted by Hans van der Zanden

A thousand days, December 13th 2009, when Boeing announced that Dreamliner one was on target to roll out and fly for the fist time in late August 2007. The plane has yet to fly but, right on target July 7th 2007, Boeing rolled out, what later appeared to have been a paper clipped Hollywood version of the 787 Dreamliner, in front of an international crowd of some 15,000 including the leading experts in this field and the corps of aviation reporters. Disgustingly disguised, nobody noticed the fake when all reached out delighted to touch this Hollywoodliner that was supposed to fly next month. As one reporter later admitted, “we were taken in by the hype”, others suspecting something wrong did not have the guts to even mention. Disreputable behavior, and more than a few at Boeing and at the FAA knew what was going on. But nobody could have imagined that first roll out, announced during a web cast March 19th 2007, would be the only target date to be met in a thousand days to come.

A thousand days, that have been a horrible dream – except that orders kept flowing in – but finally at last after countless prevarication and fabrication, cheating and lying, assurances and reassurances, and endless delays and postponements, Boeing somehow managed to fix together six test aircraft, later to be refurbished for delivery to first customers who however declined the honor, leaving Boeing no other option than to take a heavy loss and junk these liners, as did customers already with some hundred orders this year. Boeing now hopes that Junkliner one will make its first flight December 15 th 2009, and rumor has it that Junkliner two might take to the air also this year. Junkliners three to six are still in various stages of completion.

A thousand days, when the fake version was transformed into the present junk version, however, seemingly endless changes and fixes and redesigns and new designs and modifications and adjustments and conversions and revisions and adaptations, with costs spiraling out of control, could not prevent that weight kept increasing, and lightweight is what composites are all about. Exact figures are not known, but overweight of the Junkliner must be well over 15,000 pounds, with total costs heading for the twenty five billion mark. More worrisome, the Junkliner is not safe to fly.

A thousand days, when in a desperate attempt to save on weight the wing box was shaved off too much and consequently failed during testing, and had to be provisionally strengthened to withstand 150% ultimate load. The fix took more than a year and required additional aluminum stiffeners to be affixed alongside the spars as well as about 200 clips and brackets and about 500 fasteners.

A thousand days, when providing the aircraft reliable lighting protection proved far more complicated than anticipated. No problem with aluminum aircraft, it took Boeing five years of hard work to find out that the measures they deemed necessary were ‘impractical’, but the FAA agreed to relax the rules for lightning certification – aluminum aircraft are no longer benchmark – leaving the aircraft possibly defenseless in a thunderstorm.

A thousand days, when Boeing declared the blow test a success, to find out some weeks later that numerous fasteners had popped out during the test. Close inspection revealed that thousands of fasteners – Boeing admitted to some 8000 per plane – but probably much more if not all are wrongly placed. Only some were fixed, but most were left because Boeing found it again ‘impractical’ to inspect and properly fix all fasteners, and again the FAA agreed that this could wait until test flights were completed. These fasteners are loaded during twelve months of flight testing to their absolute limit in high altitudes, fast descend, simulated decompression, freezing temperatures, desert heat, lightning thunderstorm, hard landing and so on.

A thousand days, when it appeared that Boeing was not even able to properly connect a wing to the fuselage, the rationale of its existence, and waited three months to admit that during the wing-bending test serious damage occurred along the wing to body join. This happened at a very low load level, reports suggest at about 103 to 105%, or just above limit load. This means that cracks initiated at much lower load level, probably below 75% of limit load, or just half of ultimate load that the wing must be able to withstand for certification. Some thirty four delaminated sites were identified and had to be repaired in the direct vicinity of the fastener holes where the skin is connected to the stringers, which sites stretch as a row and cover some 15% of the length of the upper wing to body join.

A thousand days, when the wing to body join of the static test frame was somehow repaired and strengthened, and a new glitch turned up – they could have known. To obtain the required extremely close spark free fittings Boeing chooses to shrink the fasteners in liquid nitrogen, to expand when placed in the fastener hole. Interference fitting is common practice with metals, but should be avoided with composites at critical locations, as is here the case. The expanding fasteners will induce heavy prestressing of the composite in the direct vicinity of the fastener hole, and delaminiation is then difficult to avoid as Boeing discovered. Moreover, the prestress will increase the strength of the join, which most probably flawed the results of the wing bending test because composites creep, which means that the prestress relieves over time, loosening the fitting and gradually weakening the join once the aircraft enters service.

A thousand days, when it appeared that the models that are in place at Boeing are way out of reality, and still are. It is impossible to include in the models the stress behavior of a beefed up wing box, the effect of thousands of wrongly placed fasteners, the behavior of a fixed wing to body join including the effect of thirty four repaired fastener holes, and the effect of numerous other modifications. To sum up, the Junkliner is without reliable model, something difficult to deny by Boeing and the FAA, which means that the model can’t reliable fit the results obtained during the wing bending test, when the static airframe was subjected to limit load only – ultimate load has to be awaited until spring 2010, but should here be performed before flight testing.

A thousand days, and not a sensible word from either Boeing or the FAA on special conditions imposed for certification of the Dreamliner, like testing for bad crashworthiness, low impact performance, toxic flammability and insufficient protection of these aircraft from the direct and indirect effects of lighting. It is well known that all composite aircraft have very low damage tolerance, but safety margins have been adapted from aluminum aircraft that have very high damage tolerance, however an adaptation without any scientific justification. With aluminum aircraft the safety margin has gradually come down from 200% to the present 150%, based on long time experience. Which means that safety margins for all composite have to be adjusted to compensate for inexperience and low damage tolerance, and to withstand at least 175% ultimate load, if not 200% or more, until physical test results prove otherwise.

A thousand days, when Boeing, desperate to save on weight, decided that Dreamliners to be delivered to customers will have a completely newly designed wing box, will have completely newly designed wings, will have completely newly designed wiring, and so on. In short more than half of the structure of the Dreamliner differs completely from the Junkliner – but the plane will remain between 5,000 pounds and 10,000 pounds overweight, and will remain vulnerable in a lightning environment.

A thousand days, when Vought Aircraft Industries got fed up with Boeing and decided it better to step out the Dreamliner partnership, and Boeing had to take over The North Charleston facility that makes the rear sections of the composite fuselage at a hefty one billion; and Mitsubishi Heavy Industries who produces the centre wing box of the Dreamliner broke ranks when after careful consideration they decided it better to use traditional aluminum instead of composites for both the wing box and the wings of their own new MRJ regional jet liner, claiming that that aluminum provides more freedom of design, makes structural changes easier and appears not to affect the weight. Further embarrassment when Trans-States, the US regional carrier, placed firm orders for 50 MRJ’s and took 50 options, October 2009.

A thousand days, when finally at last the first Junkliner might line up at Everett to start a reckless flight test program, a plane with a beefed up wing box, a plane with thousands of loose and wrongly placed fasteners, a plane with provisionally strengthened wing to body joins, a plane without adequate lighting protection, a plane not properly inspected due to poor or total lack of quality control, a plane tested at far to low safety margins if not flawed, a plane without model, a plane with some 15,000 pounds overweight, a plane that does not resemble anymore the Dreamliner that Boeing intends to deliver to customers, in short a plane unsuitable, but also here the FAA agreed that this will do for certification – the Comet all over again.

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