49 CFR 215.107: Defective plain bearing box: General.

A railroad may not place or continue in service a car, if the car has—

(a) A plain bearing box that does not contain visible free oil;

(b) A plain bearing box lid that is missing, broken, or open except to receive servicing; or

(c) A plain bearing box containing foreign matter, such as dirt, sand, or coal dust, that can reasonably be expected to—

(1) Damage the bearing; or

(2) Have a detrimental effect on the lubrication of the journal and the bearings.