I find some of this very funny, places like Boeing have the labs to test the metals they use, even a small out fit can have hand held spectrometers to check metal chemistry. The only things that can affect the strength is the chemistry and the impurities or inclusions etc. and of course heat treat, but then again every shop there is that does any kind of critical work with metals has a quality control room equipped with hardness testers to verify the hardness. So if there is a problem with any supplied metals it will be discovered before it ends up on an airplane. I'm sure they still do random destructive tests on certain supplied parts that are used in critical applications. Car manufactures? Who knows what they do. And why is everyone saying STEEL just because the name of the outfit????? The problem materials were listed as non ferrous metals, NOT STEEL.

 

Perhaps slightly off the main thread-topic, but I think it would be useful to point out that, probably the single most important event in the development of modern metal-alloys and construction was, in 1954, the two in-flight break-ups of British De Havilland Comet jetliners over the Mediterranean, killing all those aboard (the Comet was the world's first production jetliner). Little was known, at the time, about the cumulative effects, over time, of high-altitude pressurization on metal aircraft frames, until a series of long, expensive, and exhaustingly difficult tests on grounded Comets finally identified the problem. A couple of similar disasters happened on early turbo-prop Lockheed L-188 Electra airliners in the late 1950s, as the effects of flutter and vibration from the outboard prop-turbine engines on the main wing spar were learned. But those two sad and unfortunate series of events, which cost the lives of a number of people, produced valuable information in future alloy-design and construction. Today, some 60 years later, the U.S. Navy and Coast Guard still fly military versions of the Electra, called the P-3 Orion. And the British R.A.F. has modernized versions of the Comet, called Nimrods.