Designing Aircraft That Withstand Failure

If you design an aircraft with failure in mind, the vehicle could be safer and fly for longer, says a Massachusetts Institute of Technology (MIT) investigator. He proposes an entirely new way of designing and building aircraft, which represents a significant departure from the approach used today.

Airplanes can be thought of as very complex systems. From the get-go, designers and engineers think of them as operating in optimal conditions, while the reality in the field is extremely different. All aircraft spend most of their time in active duty in a state of partial failure.

As such, making them capable of enduring minor flaws from the get-go could make them more resistant to adversity, suggests MIT associate professor of aeronautics and astronautics and engineering systems, Olivier de Weck.

Bits and pieces of an aircraft inevitably degrade, he explains, and the aircraft is not designed to handle these foreseeable failures from the beginning. The issue with small flaws is that they have a way of accumulating below the radar, eventually leading to a single, catastrophic failure.

When this happens, aircraft accidents are unavoidable. Therefore, we need to create an approach to building airplanes that does not allow them to go down under such circumstances.

“Think about your car. Most of the things are working, but maybe your right rearview mirror is cracked, and maybe one of the cylinders in your engine isn’t working well, and your left taillight is out. The reality is that many, many real-world systems have partial failures,” de Weck explains.

“And then the question is, in that partially failed state, how will the system perform?” he adds. De Weck explains that complex systems need to be designed from the get-go in such a manner that they can operate safely in suboptimal conditions.

He and his collaborators at MIT and the Draper Laboratory call this a multistate design approach. Unlike current methods, this takes into account the likelihood of various failures over an airplane’s time in active service. A paper detailing the new approach will soon be published in the Journal of Aircraft.

“If you admit ahead of time that the system will spend most of its life in a degraded state, you make different design decisions. You can end up with airplanes that look quite different, because you’re really emphasizing robustness over optimality,” de Weck concludes.