Testing, testing

The 787 Dreamliner program has completed the third of three large-scale structural tests - to determine whether the actual airframe performs in a simulated “crash landing” condition the same way as software modeling predicts.

Much of the results are in and we’ve concluded that the testing was a success.

The testing basically validated the analytical tool we’ll use to demonstrate compliance with the FAA’s “special condition” covering the crashworthiness of our composite structure.

image/photo

787 program personnel discuss a composite piece that was dropped as part of the final physical crashworthiness test of the 787 Dreamliner’s composite fuselage last month.

We’ll continue to model a variety of crash scenarios to comply with the FAA’s condition – which requires us to show that the 787’s fuselage is as crashworthy as today’s aluminum airframes.

The testing of the Dreamliner’s composite fuselage took place in late August at a Boeing facility in Arizona. The idea was to simulate specific impact conditions that had already been modeled on the computer, and then determine the accuracy by comparing the results of the physical test to the computer model.

In the first test we crushed a composite fuselage section slowly between steel plates. In the second test, a suspended steel plate was rammed into a fuselage section.

And in the last of the three tests, engineers dropped a 10,000-pound, 20-foot wide, half-barrel fuselage from a drop tower onto a steel-plated platform. The fuselage section included 18 seats and two loaded cargo containers. We also added extra weight to account for passengers and the top upper skin and overhead luggage bins that were removed from the test fuselage.

The results from all three of the tests matched the computational analysis.

So what’s the significance? The testing and analysis show the accuracy of our computational tools. These tools will be used to demonstrate that the 787 has comparable characteristics to today’s similarly-sized airplanes made out of aluminum. The results will be used as part of the overall certification process for the 787 for entry into service next year.

Comments (9)

Saj (London, UK):

While the road to first flight has been slow, its good to see the Dreamliner making stern progress on other fronts.

This should put paid to all the unfounded fears of ramp-rash certain people have "highlighted".

Matthew A. Nissim (Fort Lee, NJ USA):

It is good to hear that the test results were "comparable" to today's airliners, but it would be more reassuring to all to hear that the 787 crash characteristics were "better" than what we have today. I think that the public would expect some improvement. I am sure that in some respects it is more crashworthy but in others that may not yet have been proven, and that is why the word "comparable" was used.

George (Raleigh, NC):

It will be particularly interesting to learn the results of the wing testing, especially if Boeing chooses to take the test to the fracture point. It would be a feather in their engineering cap if it significantly exceeds the performance of the A380's wing.

Best of luck with the flight and static testing. Nice to watch the progress, and of course, to see Boeing winning a lot more orders than Airbus. . .

Neil D. (Everett, WA _ USA):

It was in the news today that a fired Boeing sr. engineer raised concerns about the crashworthiness, flammability and toxic gases generated from burning fiber reinforced plastic fuselage. I am interested to see the detail allegations and the debates that follow.

I recalled Beech Starship had similar construction and was certified by the FAA. I am certain the regulatory agencies and Boeing is doing all they can to mitigate safety concerns. In today's environment, product liability is paramount and I am sure Boeing and authority would not take the risk of letting safety questions unanswered!

jon (Germany):

"It will be particularly interesting to learn the results of the wing testing, especially if Boeing chooses to take the test to the fracture point. It would be a feather in their engineering cap if it significantly exceeds the performance of the A380's wing."

Would it really be so great if the 787 wing 'significantly' exceeds the performance of the A380's? Airbus came within three percent of the required load, which to me says they they didn't design extra unneeded weight into the wing structure. Sure, they had to add a few kilos to meet the requirement, but that is probably better than having a wing that can 'significantly' exceed the requirements and therefore has too much extra weight in the structure. I think Boeing would be smartest to reach the 150% and stop there. They can then use data from the test to validate and refine their computer models for the next new airplane.

It will be interesting to see how they play it.

Lumberton (Texas):

Ultimately the current "controversy" over the safety of composite materials comes down to who one elects to believe. Believe either the two huge and capable aircraft manufacturers (Boeing AND Airbus) who have bet the future on safety and reliability of these materials, and the 50+ customers who have already signed for both planes; or, does one choose to believe a disgruntled ex-employee, who left the company under less than desirable circumstances? It would be nice if not only Boeing's media relations went on the offensive here, but representatives of SPEEA and the IAM as well. Perhaps this is one time where Boeing and Airbus can work together--countering these spurious claims?

Kinbin (Taipei, Taiwan):

Ah, the "fun" of validating computer models. I had my fair share of validating models while pursuing an engineering doctorate. At the end of the day, its the applicability of so-called factors that you put into basic equations to explain / correlate the actual observed data to the modelled numbers across the spectrum of conditions.

Remember friction coefficients, heat capacities etc.? They are basically factors to be plugged into equations and formulae.

The fact that the modelled data adequately reflects the data from the actual tests at the first go is indeed a good engineering feat. Actual data should neither exceed nor underperform the modelled data by a tolerable acceptable margin to gauge its effectiveness.

James (Honolulu, Hawaii):

Boeing needs to be extremely pro-active and needs to demonstrate --CONVINCINGLY demonstrate-- that the 787 is as safe as an aluminum plane. You can't (or shouldn't) hide behind technobabble!! It could be as simple as showing a video of a drop test.

Or --better-- Boeing should follow the lead of an Illinois electric utility. This company was criticized in a CBS 60 Minutes report. The company fought back by rebutting (in video form) the 60 Minutes report, point by point, issue by issue. They didn't quibble. They showed convincingly how, when and where 60 Minutes was dead wrong.

The McDonnell Douglas DC-10 "died" in the marketplace - because of several crashes. Even though the DC-10 was a sound design, perception is reality. Remember, the media is generally technically illiterate --and guess where people get their knowledge from? Boeing needs to understand this.

ManagerJosh (Los Angeles, CA, USA):

@Jon from Germany:

It is far better to OVER-Engineer something than to under-engineer. Under-engineering something is a recipe for disasters, accidents, and loss of life. Some things are better to be safe than sorry.

If I may add, it appears, in my opinion, that Airbus had a 3% miscalculation. It's an engineering rule to always make something at 150%. 3% short doesn't really inspire confidence. If they didn't calculate this correctly, it makes me wonder what else wasn't correctly calculated.

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