Bushings are simple bearing sleeves inserted into these holes to protect them and guide the drill bit.

Fork and blade connecting rods are used, with the inner rod running on the outside of a shared bearing sleeve.

A common arrangement for forked rods is for the fork rod to have a single wide bearing sleeve that spans the whole width of the rod, including the central gap.

In June, the inspector general said the Defense Logistics Agency paid Boeing $13.7 million more than it should have for spare parts, including $2,286 apiece for an aluminum "bearing sleeve" that should have cost $10.