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© Simon Butler/Flickr An Air India plane bound for London Gatwick airport crashed shortly after take-off on 12 January in Ahmedabad, western India. Flight AI171 was carrying 242 people, including 169 Indian nationals, 53 Britons, seven Portuguese and one Canadian. Here, Professor Ali Elham, from the University of Southampton’s Department of Aeronautics and Astronautics, speaks to The Conversation’s Paul Rincon about the plane involved in the crash, Boeing’s 787 Dreamliner. How does Boeing’s 787 Dreamliner differ from other passenger planes? The Dreamliner was a huge breakthrough in aircraft design. For example, it was the first Boeing aircraft with more than 50 per cent composite material in its structure. In this case, composite material refers mainly to carbon fibre. This carbon fibre was replacing parts of the structure that would have been made from aluminium in previous types of aircraft. This contributed to a huge reduction in aircraft weight. There were many innovations in the 787, making it very different from previous iterations of Boeing aircraft, such as the 747 and 767. The combination of new engines, improved aerodynamics, and significant weight reduction – largely due to the use of composite materials – resulted in notable reductions in both fuel consumption and carbon emissions compared to previous-generation aircraft. Another feature was the greatly increased electrification of the plane, with more use of batteries for onboard power systems. What is the Dreamliner’s safety record like? The Dreamliner has a very good safety record and has been flying for many years without significant problems. But when the plane was new, in 2013 or so, there were a few incidents in which the aircraft’s lithium-ion batteries overheated, in some cases resulting in smoke or even catching fire, both on the ground and during flight. There were no casualties and the aircraft were all able to land safely. But Boeing grounded all Dreamliners for a few months. Boeing intensively investigated the problem. They redesigned the batteries, they redesigned the battery containers and then they ran tests and an extensive certification process that allowed them to return the Dreamliners to flight. Since then, there have been no incidents with batteries as far as I am aware. Batteries were used instead of getting power from the gas turbines in the engines. The power is used for instruments, for electronics and many other aircraft systems. Increased electrification – getting more of the aircraft’s power from batteries – contributes to reducing carbon emissions, because the gas turbines run on kerosene. Do any details currently known about the crash narrow down the search for the cause? It’s too early to say anything about the cause of the crash, and as far as I’m aware no official details have been released about the cause. Generally speaking, however, when you investigate air crashes, they often involve a chain of problems. One thing happens, then a number of events follow from that. So it might not be one cause here. This crash occurred shortly after takeoff. While flying is statistically the safest form of transport, the takeoff and landing phases are generally considered the most critical. This is because aircraft operate closer to the ground, with less time and altitude to respond to technical issues or sudden changes. Although not inherently dangerous, these phases carry a higher risk of incidents compared to cruising at altitude. What will the crash investigation focus on? They will investigate everything. They will search for the data recorders (black boxes), which are designed to survive a crash. If these are recovered, investigators will be able to view all the flight data, hear all the cockpit conversations. They will take all the information from the control tower. Sometimes clues can be found from all this data. They will also examine the wreckage of the aircraft in detail. It’s a different situation from the Boeing 737 Max groundings, which followed two crashes linked to a specific and repeatable software flaw. Similarly, when the Dreamliner first entered service, a series of battery overheating incidents revealed a systemic issue that led regulators to temporarily ground the fleet. In the current case, unless investigators identify a recurring technical problem that poses an immediate risk to other 787s, a fleet-wide grounding would be unlikely. Safety is always the top priority, but regulatory responses typically depend on whether an issue appears to be isolated or part of a broader pattern. It must be said that the 787 Dreamliner has a very good safety record. It had a very long certification period with the Federal Aviation Administration (FAA) in the US. Ali Elham, Professor of Design Optimisation, Department of Aeronautics and Astronautics, University of Southampton This article is republished from The Conversation under a Creative Commons licence. Read the original article.

Boeing

What do we know about the Boeing 787 Dreamliner involved in the Air India crash? Expert Q&A