Originally Posted by
incompleteness
I'm not sure what diameter the arrestor bolts are because my eyeballing skills aren't up to it, but they must at least be 6/32. Your basic vanilla 6/32 bolt has a shear strength around 2000 lbs. The two at the bottom have two shear planes each so each one is good for 4000 lbs.
But what if in the confusion of bolt definition they used an available fully threaded bolt (called set screw (with no head they are called grub screw)) instead of one only partially threaded (just called bolt). How much would that reduce the shear strength. And in this case it's bending and hitting/pushing on the middle by the roller pins strength we are talking about, not pull strength.
(Definitions on bolt type names are from the website of the supplier of stainless steel hardware inox.ie)
This could also have been done by a Spirit employee and especially if they thoght Boeing routinely would replace them later.
They could even have used non hardened bolts.
That Alaska plane needs to be taken apart to see if not at least one bolt have fallen into a gap and down into the belly of the plane. If they did fail its unlikely they all failed at the same time.
And I wouldn't worry to much about lose bolts on other planes. It's the precense of the bolt that is important. Not its thightness. And a castellated nut with a split pin would stop it coming out altoghether, unless it was broken in two.