What did the flight engineer do in the days of 3-man flight crews?

[LSLGuy]

I was a flight engineer for about 5 years on 727s. By then (late 80s thru early 90s) F/Es were pilots too. That was not true back in the beginning of F/Es during and just after WWII.

Here are some relevant posts including some history and evolution of the job:

Can the flight engineer fly the plane?

Former airline pilot & flight engineer (“F/E”) … Pretty much as folks above said. Very few F/E equipped airplanes are still in use. And of those still flying, the vast majority are in the cargo biz. And concentrated in the primitive or poorer parts of the world. In about 1965 the FAA mandated that all flight engineers of US commercial passenger planes be pilots. Prior to that it was a separate career growing out of aviation maintenance technician. Since then, in US passenger service t…

If the cockpit fell off a airliner while in mid-flight, could it be landed safely?

That’s a *little *behind the times. The last airline navigators disappeared in the early 1960s. That reduced the then-current 4-man crew on long range flights to 3: Captain, co-pilot, and flight engineer. The flight engineer is sort of an on-board mechanic and the equivalent of a ship’s engineering officer: responsible for operating all the mechanical systems so the pilots can concentrate on steering. So hydraulics, engines, electrical, HVAC, fuel, etc. The last mainstream air…

There’s a bunch of ancillary info in those threads that may bear on the OP’s curiosities.

And here specifically is a dissertation on one specific duty of the flight engineer that’s been obsoleted by a different approach to redundancy.

Multiple generators in phase. How?

Multi-engine aircraft aren’t much different from submarines in this regard. Older multi-engine jets, say airliners from the 707 through the early 737 and 747 used a similar system. Each engine drove an AC generator through a hydraulic pump/motor assembly called a “constant speed drive” or CSD. The CSD tried to maintain a constant output (ie generator input) shaft RPM regardless of engine RPM. That way the generator’s frequency would also be constant, at least within the tolerance of the CSD’…

And finally, what happened to them:

Defunct professions

For me the defunct profession is “Flight Engineer”. When I started in the industry in the late '80s there were probably 10,000 flight engineers working in the US. Now it’s closer to a couple hundred. I bet it’ll be zero in another 5-ish years.

I’d be happy to talk more about any of this if anyone has specific questions.