Carbon Fiber Making Inroads In New Applications Despite Safety Concerns

Boeing 787


The Boeing 787 Dreamliner recently completed its first Trans-Pacific passenger flight, landing in Boston as JAL 8. The JAL service is New England’s first Asia route. It’s made possible by the 787’s efficient design, which allows airlines to provide service, even with partially full flights, due to significant savings on fuel.

Unlike previous generations of Boeing planes, which were made primarily of aluminum, the 787 is 80% composite by volume; by weight its materials are 50% composite, 20% aluminum, 15% titanium, 10% steel, and 5% other. Aluminum is used on the leading edges of the wings and tail, while titanium is used primarily on the engines and fasteners.

A 787 contains approximately 32,000 kg of carbon fiber reinforced plastic (CFRP), made with 23 tons of carbon fiber. Since carbon fiber composites have a higher strength-to-weight ratio than traditional aircraft materials, they make a lighter airplane. For the most part, composites are used on the wings, tail, doors, fuselage and the plane’s interior.

Composite materials, like those used in the construction of the 787, are not unfamiliar to cyclists. Just as with bicycles, when the 787 was introduced, controversy arose about the safety of using carbon fiber composites to construct planes. Carbon fiber is different from metal; it does not visibly show cracks and fatigue. This lack of visible wear led people to question the safety of carbon fiber use in airplanes.

A few years ago, a former senior aerospace engineer at Boeing’s Phantom Works research unit, Vince Weldon, went public with concerns that the 787 Dreamliner was unsafe. He claimed that “in a crash landing that would be survivable in a metal airplane, the new jet’s innovative composite plastic materials will shatter too easily and burn with toxic fumes.”

Weldon wrote a letter expressing his concerns. In the letter he made several key points:

“The brittleness of the plastic material from which the 787 fuselage is built would create a more severe impact shock to passengers than an aluminum plane, which absorbs impact in a crash by crumpling. A crash also could shatter the plastic fuselage, creating a hole that would allow smoke and toxic fumes to fill the passenger cabin.

After such a crash landing, the composite plastic material burning in a jet-fuel fire would create ‘highly toxic smoke and tiny inhalable carbon slivers’ that ‘would likely seriously incapacitate or kill passengers.’”

Boeing’s tests of these allegations showed that shards of composite material released in a crash are not a shape which is easily inhaled. Further, the smoke produced by composites in a jet-fuel fire proved to be no more toxic than the smoke from the crash of an aluminum plane. And Boeing responded to the charges by pointing out that composites have been used on wings and other passenger aircraft parts for many years, without incident. To ensure the safety  of the planes, they instituted special defect detection procedures to identify any hidden damage.

These concerns about the safety of carbon fiber, and the aircraft industry’s responses to those concerns, are very similar to what we hear in the cycling world. Proponents of newer, stronger materials want to press forward with their use due, in part, to their confidence in the properties of such materials. Carbon fiber is stronger and lighter than metal. This is true whether it is used to construct airplanes, race cars or bicycles.

Few stories of carbon fiber disasters have been made public in those industries where the material has been used for years. Yet, stories abound of catastrophic carbon fiber failures, with respect to bicycles.

Such safety record differences are hard to reconcile. Manufacturing processes may play a role in how safe a carbon fiber composite is when used in the real world. Quality control may be another factor which separates the safety features of carbon fiber used in airplane manufacture versus bicycle manufacture.

An airplane is a much more sophisticated and expensive piece of equipment than a bicycle. And, perhaps the fact that multiple lives are on the line, in the event of a failure, drives manufacturers to take extra care when building aircraft. When a bicycle fails, one person is injured or killed.

Since only one person is harmed at a time, it is more difficult to compile accurate statistics on how dangerous carbon fiber bicycles or carbon fiber bicycle parts are for the cyclists who use them. The difference is personal injury versus a tragedy involving multiple lives. One is an isolated incident, the other an accident of catastrophic proportions.

Therefore, it’s difficult to tell how many carbon fiber bicycles actually fail catastrophically. What is simple to determine is that no cyclist wants to be among the group whose bike fails unexpectedly.

What cyclists must do is find a way to compare materials and manufacturing processes used in other industries with those of the bicycle industry. Perhaps bicycle manufacturers can learn, from the designs and product testing done in other industries, to make bicycles safer.

Carbon fiber is here to stay. We will see it in cars, airplanes, bicycles, and possibly other products as well.

We cannot turn back time to a simpler day when metal, with its gradual deterioration and failure, was the norm. Some of us can choose traditional materials. But, acquiring those materials will probably become more difficult and expensive as time goes on.

Right now, all we have is anecdotal evidence and fear. As cyclists, and consumers, the best we can do is to demand accountability. We should work together to formulate an idea of how many cyclists sustain injuries from carbon fiber use in bicycles. And, if we find that carbon fiber use is inherently more dangerous when used in the manufacture of bicycles, we should demand changes from manufacturers until the number of injuries from their products is negligible.

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