Welcome back to the our channel for a feature about how state-of-the-art airplanes get their certificates to operate. In the first place, a series of performance tests are carried out to figure out the performance characteristics of the airplane. With the completion of those tests, the test team focuses more on the components, such as evacuation slides. In the last week or so a 737-800 made a hard landing here in the US. So hard it drove the left landing gear up and through the top of the wing! Haven't seen that for a while, but it was a good example of how the gear was designed to do that. The wing has fuel in it. If the gear didn't go up and out the top, it would be contained in the wing. That might/could rupture the fuel tank and leak fuel all over. With the aircraft sliding on the left engine, there were sparks all over. Fuel and sparks could/will result in a fire, with the port side blocked off from the fire. Not good! On this one, everyone survived.