In A Case Study in Aircraft Design: The Boeing 727, published as a retrospective in 1978, the authors repeatedly refer to what would generally be called a flight engineer as the third crewman.
This clearly predates any need for political correctness but diverges from all other references I have seen for the crew position of the non-flying member responsible for powerplant monitoring and some aircraft maintenance.
Was this driven by pressure from customers at some point during the project? Is there any other precedent for this title?
The only other reference I can find for the term is in the Wikipedia article for the Douglas A-3 Skywarrior.
On further looking, I see a Boeing 720 operations manual that refers to its third crewmember as the systems pilot - another term not commonly used.
The 70-page document has a dozen references to third crewman and none to flight engineer.
An extract from the Flight deck description shows the frequency of use.
The question was motivated by this very deliberate use of a term not otherwise used in literature at a time of transition in aircraft design. The motivation looks to be marketing related, but I can't see how changing the title of the crewmember would modify customer perceptions and wanted to understand if this attempt at a form of technical newspeak had any impact.
It is not intended to reflect on the clearly valuable contribution by the engineer in an aircraft designed before automation removed the need to monitor the status of the aircraft systems.
So far, responses have questioned many possible meanings of the question, but none have had an opinion on the straightforward interpretation. While the question is not related to physical aircraft structures, it would inform positioning of the product in a marketplace beginning to notice the arrival of Airbus.