Duty engineer was a title for a Starfleet engineering officer. When the chief engineer was off-duty, this engineer was in charge of engineering.

On the USS Enterprise-D, in 2367, the duty engineers for the third shift were Sarah MacDougal and Leland T. Lynch. (TNG: "Galaxy's Child")

In 2369, Chief Engineer Geordi La Forge requested a display of the Engineering Department Duty Roster for the next three days. The names of duty engineers for each of the duty shifts were listed in this roster. (TNG-R: "Aquiel")