49 CFR § 215.115 - Defective roller bearing.
(a) A railroad may not place or continue in service a car, if the car has -
(1) A roller bearing that shows signs of having been overheated as evidenced by -
(i) Discoloration; or
(ii) Other telltale signs of overheating such as damage to the seal or distortion of any bearing component;
(2) A roller bearing with a -
(i) Loose or missing cap screw; or
(ii) Broken, missing, or improperly applied cap screw lock; or
(3) A roller bearing with a seal that is loose or damaged, or permits leakage of lubricant in clearly formed droplets.
(1) A railroad may not continue in service a car that has a roller bearing whose truck was involved in a derailment unless the bearing has been inspected and tested by:
(i) Visual examination to determine whether it shows any sign of damage; and
(ii) Spinning freely its wheel set or manually rotating the bearing to determine whether the bearing makes any unusual noise.
(2) The roller bearing shall be disassembled from the axle and inspected internally if -
(i) It shows any external sign of damage;
(ii) It makes any unusual noise when its wheel set is spun freely or the bearing is manually rotated;
(iii) Its truck was involved in a derailment at a speed of more than 10 miles per hour; or
(iv) Its truck was dragged on the ground for more than 200 feet.
(3) Each defective roller bearing shall be repaired or replaced before the car is placed back in service.