46 C.F.R. § 11.512
Service requirements for national endorsement as First Assistant Engineer of steam, motor, and/or gas turbine-propelled vessels
(a) The minimum service required to qualify an applicant for endorsement as First Assistant Engineer of steam, motor, and/or gas turbine-propelled vessels is—
(1) One year of service as an Assistant Engineer while holding an MMC with a Second Assistant Engineer endorsement; or
(2) One year of service as a Chief Engineer-Limited and completing the appropriate examination described in subpart I of this part.
(b) A person holding this endorsement may qualify for an STCW endorsement, according to §§ 11.327, 11.331, and 11.333 of this part.