- SPECIAL REPORTS
When you take a product like a commercial jetliner and spread the supplier base all over the world, many are quick to blame quality control failures on far-flung logistics. Charred batteries in the Boeing 787 Dreamliner and cracked brackets on superjumbo Airbus wings quickly drew critics who said outsourcing doomed the planes.
Many say the aerospace industry cannot use widespread supply chain models like those in the automotive industry. I say a better approach to vendor partnerships would have made all the difference for these companies.
When it comes to testing, every company in the world has the same choices to make, the same risks to avoid. If mission-critical parts fail, customer flight is almost certain. Ironically, in the aerospace industry, when batteries smoke and wing brackets crack, flight is not even an option either literally or figuratively. About the only thing you can count on is delays and lost sales.
Automotive companies have a slightly different dynamic. Other suppliers may quickly step in if a competitor has a leaky engine cover. It’s the same with medical device manufacturers and industrial equipment OEMs—they must either meet specifications or go home. (The aerospace industry is by no means the only industry with exacting standards.)
The root cause of problems for Boeing and Airbus really has more to do with untested technology than supply chain logistics. Boeing engineers in Chicago can meet online with colleagues from Beijing and share CAD files throughout the design phase. French engineers and their colleagues around the world use the same, top-of-the-line CAD software for their collaborative designs at Airbus.
For example, when a big customer demands quieter engines so the A380 can operate near major cities, Airbus is motivated to help. Rest assured, Airbus uses the best software to simulate stress on wing brackets to see if they will hold up with heavier (but less noisy) engines.
Boeing also uses top-of-the-line simulation to test the capabilities of new, lightweight lithium-ion batteries. These batteries help make Boeing jets gas sippers that are more economical to operate. In fact, these batteries are a factor that makes it conceivable for a modern commercial aircraft to fly across oceans with only two engines instead of four. That is potentially a game changer within current FAA standards.
Throughout the aerospace industry, simulation is used extensively. Then test flights start and the real problems begin. Brackets fail. Batteries catch fire. What happened?
For one thing, you need a testing specialist who understands not only test technology but also the demands placed on your product under real-world conditions.
Another important consideration is trust and partnership. A supplier and its testing group is assured better results if they have mutual access to the entire test chain from product development to durability to production testing. Early engagement of test engineers means problems are identified before design is frozen so that costs are controlled.
There was a lot of excellent simulation and lab work to test parts and components before the 787 and the A380 got off the ground. Management at these companies will tell you that testing was probably the most thorough part of the process. Despite all their preflight efforts, in actual flights critical systems failed on both planes causing massive production delays.
Perhaps we should thank Boeing and Airbus for reminding us that even with tremendous funding for simulation and lab work, it is virtually impossible to control for every factor. Unfortunately, for these aerospace giants, they did not follow the basic tenets of test-centric assembly.
Test-centric assembly is a method developed for failsafe leak testing more than four decades ago. The concept eliminates bad parts before they become even more expensive to scrap or rework.
Now, with robots and factory Ethernet, flexible automation is the new standard in manufacturing, and leak testing has evolved to adapt. What has not changed are the fundamentals of leak testing. They are as constant as gravity.
Dunk testing, the oldest technique in the world, still works, but it’s slow and has limits. Bubbles get trapped. Tanks become contaminated, and that drives up maintenance costs. Part size, complexity and other factors limit what can be tested this way. Pressure rise and decay methods are easy, often requiring merely a gauge, but data is hard to interpret. In addition, mechanical parts often fail, so maintenance is constant and accuracy is dicey. Mass-flow leak testing is faster and more reliable. Helium testing is even more so, but at a much higher cost.
All have pros and cons. Some work well in high-speed production settings; some do not. Audit testing dictates leak-testing choices in ways that do not apply in production testing. Durability testing is another factor that affects choices.
The temptation to lean on software for product testing may be high, but even Boeing and Airbus with all their access to simulation cannot be sure that every real-world factor is programmed accurately into their software. Your best production engineers may know how to simulate, but they may not know when to use certain test techniques to find hidden issues.
Test-centric assembly is important because it contributes to higher yield. It’s a core asset to quality control, and it boosts overall profitability. When properly applied, the concept ensures that assemblies meet standards deemed as failsafe.
Testing experts know techniques to ensure the leak testing process does not overlook concerns like altitude, temperature and humidity. Even the act of pressurizing a part can affect results, and sometimes parts just have to be tested in exactly the orientation they are mounted on the final assembly.
It is tempting to think you have the right people to determine all your testing needs. You may have the greatest production engineers in your industry, but given the experience with Boeing and Airbus, doesn’t it make sense to collaborate with test experts when your brand is on the line? What test-centric partnerships have you created to ensure that new products avoid real-world pitfalls?
Jacques Hoffmann is President of InterTech Development Co., which designs and builds equipment for leak testing, functional testing and test-centric assembly. He can be reached at 847-679-3377.
Editor’s note: “Hoffmann on Testing” is part of a series of guest spots by industry experts that will appear regularly on ASSEMBLY’s blog page. Check back frequently to read more commentaries from Jacques, as well as contributions on automated assembly systems, machine vision, robotics and ergonomics.