Space.com is carrying this report on what would seem to be a routine maintenance item... the replacement of some securing bolts on a large antenna structure in space shuttle Atlantis's cargo bay. Routine, until you read this:
Earlier this week, [NASA shuttle program chief Wayne] Hale said that between six and eight engaged bolt treads are preferred for each bolt to ensure they will hold Atlantisí 304-pound (137 kilogram) Ku-band antenna assembly fast during the eight and a half minute climb into orbit. Inspections found that only two of Atlantisí four antenna bolts were suitably secured, though a survey of all three NASA shuttles found that some were attached by as little as two-thirds of a tread, he added.
Let's hear it for government project quality control! However, "treads" sounds like it might be different from "threads", so who knows, maybe it means something else entirely. All I can say is, if I found out only a quarter-turn of a bolt held something important on my car, I'd be pretty quick getting a longer bolt!