46 CFR §61.20-18

1. (a)Each tailshaft must be drawn and visually inspected at each examination.
2. (b)On tailshafts with a taper, keyway, (if fitted) and propeller designed in accordance with American Bureau of Shipping standards to reduce stress concentrations, the forward 1/3 of the shaft's taper section must be nondestructively tested in addition to a visual inspection of the entire shaft.
3. (c)On tailshafts with a propeller fitted to the shaft by means of a coupling flange, the flange, the fillet at the propeller end, and each coupling bolt must be nondestructively tested in addition to a visual inspection of the entire shaft.