> Do you know what happens when a 19-ton propeller has a crack? The story of these propellers is interesting. They were to be cast from a single piece of metal

> Do you know what happens when a 19-ton propeller has a crack? The story of these propellers is interesting. They were to be cast from a single piece of metal, and were precisely of the largest dimension fit for the largest metallurgy facility in France (because it's a top secret design, they had to be made in a domestic factory). However, the project was so delayed that the factory closed its doors several years before it to be able to build the propellers... So another company got to build them, but they were so large that they had to cast them in several parts and weld them together instead of a single cast, which is apparently NOT best practice and hadn't been ever done before.