14 CFR § 63.33 - Aircraft ratings.
(1) Reciprocating engine powered;
(2) Turbopropeller powered; and
(3) Turbojet powered.
(b) To be eligible for an additional aircraft class rating after his flight engineer certificate with a class rating is issued to him, an applicant must pass the written test that is appropriate to the class of airplane for which an additional rating is sought, and -
(1) Pass the flight test for that class of aircraft; or
(2) Satisfactorily complete an approved flight engineer training program that is appropriate to the additional class rating sought.