A few months I took this series of photographs while waiting to board a trans-Atlantic flight home. First, a small ladder was placed in front of the engine. Then a technician arrived, climbed onto the ladder and spread a blanket on the cowling before kneeling on it and spinning the fan blades slowly. He must have spotted something that concerned him because he climbed in, lay on the blanket and made a closer inspection. Then he climbed down, rolled up the blanket and left. A few minutes later he returned with a colleague, laid out the blanket and they both had a careful look inside the engine, after which they climbed down, rolled up the blanket put it back in a special bag and left. Five or ten minutes later, they were back with a third colleague. The blanket was laid out again, the engine inspected by two of them at once and a three-way discussion ensued. The result was that our flight was postponed while the airline produced a new plane for us.
Throughout this process it appeared that the most sophisticated inspection equipment used was the human eye and a mobile phone. I suspect that the earlier inspections were reported by phone to the supervisor who came to look for himself before making the decision. One of the goals of our current research is to develop easy-to-use instrumentation that could be used to provide more information about the structural integrity of components in this type of situation. In the INSTRUCTIVE project we are investigating the use of low-cost infra-red cameras to identify incipient damage in aerospace structures. Our vision is that the sort of inspection described above could be performed using an infra-red camera that would provide detailed data about the condition of the structure. This data would update a digital twin that, in turn, would provide a prognosis for the structure. The motivation is to improve safety and reduce operating costs by accurate identification of critical damage.