My first reaction was Quality too. Flight deck people have a color code for the jerseys they wear to give an easy way to tell what they do from where the Air Boss watches. A friend of mine who was on carriers calls them skittles. Idk what the red shirt means but guessing Ordnance, which I think would not be involved with delivery of an engine. Fuel guys wear purple and are called Grapes. The coded symbols on those cranial helmets could also indicate job or what department they're from. Or, a SailorAnon which is what I prefer to believe.