When lessons learned from history may provide any guideline there is something serious to worry about validation of Boeing’s new all composite aircraft.

December 10^th 2009, Boeing reported that “the program has validated the airplane structure for the 787 Dreamliner”, and announced that, subject to weather conditions, Dreamliner one is expected to make its first flight within a week or so. First flight will take place very careful, with sunny conditions and limited wind, and no problems are expected. For the moment the whole first flight exercise is to appease reporters and investors. Once the window is extended conditions get more severe and serious problems will undoubtedly surface, and one can only hope and pray that nobody gets killed. Not since the Comet has a civil aircraft been so badly  prepared for flight testing.

Difficult to depict on what grounds the structure of the aircraft has been validated. As was argued in the previous post, the aircraft is without reliable model. All main structural tests performed so far – wing box, blow test and wing bending test – failed by wide margin from the modeled predictions. Each time the structure required comprehensive strengthening, provisionally applied, and only the wing box sustained ultimate load. The blow test has not even been repeated, nor has properly strengthening been performed leaving the planes with thousands of wrongly place fasteners. Remember that it took only a wrongly chosen O-ring to destroy the Challenger. The repeated wing bending test has been performed to limit load only, that is two third of the load required for specification. Validation cannot be described otherwise than based on wishful modeling.

Another aspect that has to be considered is that the test flight aircraft differ in significant way from the ground structures that have been tested so far, and are dissimilar. Each of these aircraft present a differing structure, that is with multiple specific modifications, redesigns and repairs, when Boeing and its partners slowly learned to deal with composites – the extend of which deviations is not clearly known to Boeing. It would be interesting just to learn about the weight of each basic structure and the numbers and types of fasteners applied in each of the flight test aircraft. This means that these aircraft will behave differently, for the better or the worse, leaving the models ineffective.

Remember that structural problems with the Comet surfaced once the planes were in service, as was also the case with for example the F111. So many were killed, so many tragic accidents could have been easily avoided given ample time for reasoning and development. The question is, why were they killed.

Management and engineers at Boeing – and for that part the FAA – are under immense pressure to deliver what is physically virtually impossible. Stakes have probably never been so high in corporate history. One can doubt the design rationale, that is argumentation and justification leading to the decision to validate the structure – sound reasoning cast in shadow by commercial interests. This went terribly wrong with the Comet, and played also havoc with the accident of the Columbia and when the Space shuttle Columbia was still in orbit. In hindsight, the causes that led to these accidents are similar, too much pressure leading to ignorance. All involved now at Boeing are undoubtedly well aware that with these past accidents nobody was convicted for such behavior, too much at stake. This may be poor comfort for those facing the rising sun, let the lessons learned therefore serve at least to avoid future ignorance.

Boeing is presently at crossroads to decide whether to proceed with their all composite adventure, now the advantage of lightweight has diminished . Be aware that it will take years and much more resources to develop a reliable and safe all composite aircraft – probably another thousand days to come if ever – so much unfinished business and issues that have not been properly approached and researched. Ignorance will inevitably lead to a repeat of the Comet.

Ignorance that led to the accidents with the Comet, Concorde and Columbia is further detailed in separate chapters that can be downloaded at this site.

A thousand days, December 13^th 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 7^th 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 19^th 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.

The launch of the Space Shuttle Endeavour last Tuesday once again draws attention to the vulnerability of the heat shield. Video and photo images taken during the launch  revealed debris that broke loose from the external fuel tank. To the surprise of NASA engineers who commented “We don’t understand why that happened”, foam loss can be observed on seventeen different areas of the external tank.  Debris impact can cause serious damage to the Shuttle’s heat shield during the first 135 seconds after launch, when the Shuttle is still in the dense lower regions of the atmosphere. One debris impact occurred at one minute and 47 seconds into the flight and eroded the black outer coating of heat shield tiles in three areas. Another impact eight seconds later produced another area of outer-coating erosion. Preliminary inspections showed no obvious problems, but data analysis will take several days to complete. Impact damage is also a major problem with all composite aircraft, which are significantly at more risk than the Space Shuttle. Read the rest of this entry »

A comment was received  on ‘An impossible dream’ concerning the A380 discussed in chapter 1 (pages 6-9) and is here answered. The original comment is printed below. For more comments go to posting June 9, 2009, below.

Thank you for your comments – they are sincerely and very much appreciated.

First, let me say that the book is not in any way intended to be about the Airbus A380 – an airplane and engineering marvel that I greatly admire.  But it is an aircraft that paved the way for composed aircraft, and that is the reason that I included a small section in the book on the A380. Read the rest of this entry »

The Boeing Co. announced Tuesday it has agreed to buy a facility of Vought Aircraft Industries for $580 million in cash, in addition to the release of an undisclosed amount of debt. “Integrating this facility and its talented employees into Boeing will strengthen the 787 program by enabling us to accelerate productivity and efficiency improvements as we move toward production ramp-up”, said Scott Carson, president and CEO of Boeing Commercial Airplanes. “In addition, it will bolster our capability to develop and produce large composite structures that will contribute to the advancement of this critical technology.”

Did Boeing have a choice? Read the rest of this entry »

All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident.

Arthur Schopenhauer (1788 – 1860)

‘An Impossible Dream’ goes through stage one at the moment but will reach stage three sooner than later. For many it is still difficult to believe that civil aircraft can’t be built all-composite; that is, some 80% out of composites by volume including the complete skin. For those familiar with materials science this all-composite approach has been incomprehensible from the start. This could only end in failure. One can only wonder why so many scientists involved themselves with these projects and even came to the defense. Most worrisome is that the scientific community kept silent – if not totally silent – when developments unfolded, not to mention the press. But soon enough we will read different stories and experts will arise from nowhere. It happened before, far too often actually, just read the appendices in my book about the Comet, Concorde and the Columbia in particular (can de downloaded on the right). Read the rest of this entry »

‘An Impossible Dream’ – will be published later this year. Draft text of the book is here presented for comment. Copyright applies.

About all composite aircrafts.
‘An Impossible Dream’ presents an in depth review of the application of plastic composites in aircraft, in particular all-composite aircraft presently developed by Boeing – 787 Dreamliner – and by Airbus – A350 XWB. Composites do not provide the expected weight savings and the safety of all-composite aircraft can be seriously questioned. These aircraft will never attain the safety standards set by aluminum aircraft – not even near. It is therefore difficult to understand why Boeing and Airbus engage themselves with such projects. The book presents a detailed review of the development of these aircraft, reflects on history and discusses the pros and cons of composites in some detail – an alternative approach is put forward.

Read the rest of this entry »