14 CFR §120.31

1. (a)Each certificate holder or operator shall provide each employee performing a function listed in subpart E of this part, and his or her supervisor, with the training specified in that subpart.
2. (b)No certificate holder or operator may use any contractor to perform a function listed in subpart E of this part unless that contractor provides each of its employees performing that function for the certificate holder or operator, and his or her supervisor, with the training specified in that subpart.