Originally posted by Racer X 69 Originally posted by KC0PET Whilst getting loaded into the flying sardine can.
I look at this photo and see the stuff airplanes are made from.
Aluminum skin and structure, titanium bolts, aluminum collars (nuts), aluminum rivets.
Originally posted by KC0PET Sounds like an occupational hazard
Notice on the door opening frame. Two orange things.
Those are called collars. People might call them nuts, but for airplanes they are called collars. The nut part breaks off on installation, once the designed torque limit is reached.
So those collars are threaded onto a couple of Highlok bolts. Awesome bits of engineering, titanium, and coated to prevent corrosion. After the Highlok and the collar are assembled, the drawing finish must be restored.
Also, notice the amount of thread sticking out of the collars. There is too much sticking out, it is called pin protrusion. It is also noticeably different between the two, but that is another matter. The grip length of the stack up (all the metal bits of aircraft structure getting fastened there) has not been considered by the mechanic who performed the repairs or non conformance work.
Because the bolts are too long, the collar cannot properly expert the correct clamping force and usually breaks off before it has been achieved.
On that airplane some work has been done, and it would not pass my inspection before submitting the work for final inspection, and it clearly would not pass inspection from any of the QA techs that look over the work we do where I work.
But hey, they design the things with a 10 to 1 failure factor (for every 10 rivets and/or bolts, only 1 s required).