The prestigious MIT Technology Review has named General Electric's work on 3D printing as one of its "10 Breakthrough Technologies 2013".
Specifically, GE is developing a metal nozzle for its LEAP jet engine. They will use 3D metal printers to produce the nozzles, which will be lighter in weight due to an advanced design producible only on 3D printers.
Wait, we've heard this story many times before. A company improves their business process by involving 3D printing. What's the big deal?
The big deal here is the volume. GE is MASS PRODUCING these nozzles with 3D printing. They are not producing mere prototypes. Even more importantly, this is a critical piece of the engine of an aircraft, something you don't fool around with. This indicates the serious capability of 3D metal printing technology.
While we say it's mass produced, there is a caveat: Each engine requires some 10 to 20 nozzles, and there only so many engines on order. In total GE will require some 25,000 nozzles. That sounds like a lot, but it's far fewer pieces than say a one million piece mass production order. So yes, they are mass produced for an industry that requires "small run" mass production.
A 3D printing milestone nevertheless.