49 CFR §230.100

1. (a)Tender truck axle condemning defects. Tender truck axles with any of the following defects shall be removed from service immediately and repaired:
   1. (1)Axles that are bent;
   2. (2)Collars that are broken, cracked, or worn to 1/4 inch or less in thickness;
   3. (3)Truck axles that are unsafe on account of usage, accident, or derailment;
   4. (4)A fillet in the back shoulder that is worn out; or
   5. (5)A gouge between the wheel seats that is more than 1/8 of an inch in depth.
2. (b)Tender truck journal condemning defects. Tender truck journals with any of the following defects shall be removed from service immediately and repaired :
   1. (1)Cut journals that cannot be made to run cool without turning;
   2. (2)Seams in axles causing journals to run hot;
   3. (3)Overheating, as evidenced by pronounced blue black discoloration;
   4. (4)Transverse seams in journals of iron or steel axles; or
   5. (5)Journal surfaces having any of the following:
      1. (i)A circumferential score;
      2. (ii)Corrugation;
      3. (iii)Pitting;
      4. (iv)Rust;
      5. (v)Etching.