> Wilson told Grassley that this cup is specially manufactured to plug into aircraft systems, and because it connects to the aircraft, the replacements need to be certified as airworthy by the FAA.

I'm actually curious what goes into certifying the airworthiness of a heated coffee cup. Could faulty wiring in it legitimately damage the plane's power systems or something? Or cause interference of some kind?

It is a cup that plugs into the electrical outputs on a military airplane.

The more that the DoD stands up 3d printing, the less these kind of things will be an issue, particularly once they start doing more 3d printing in metal.