I am currently a Flight Engineer on MC-130P Combat Shadows.
Yes, you need to be prior Mx, (Air Force 2AXXX AFSC, Army-USMC-Navy, various Rates/MOSes), or be an A&P, AMT or hold at least a Private Pilot License to meet the pre-requisites.
I'll tell you that NOBODY is going to hire a new guy off the street...even a guy flying for the regionals...and then send him to Basic and then the FE tech schools. No matter what. I bet a $100 bottle of scotch on that one.
Helicopters had a high school to flight school FE program for a while, but it didn't work out well AT ALL. Flight Engineer on any USAF airframe that requires ENG's is going to be DEMANDING. All 4 of my tails on our flight line are 1966 models, so you do the math. FE is responsible for preflight of the ENTIRE aircraft, as well as running all checklists, ensuring compliance, running the flaps and NVG compatible lights, runs the fuel panel, the electrical panel, the anti-ice and de-ice panel, runs air cnditioning system and cabin pressurization system...computes manual charted Take Off and Landing Data (TOLD), and post said data to mini cards for the pilots to reference. Handles all basic Maintenance that a crew chief would normally do when on the road without Crew Chief support. For my airframe, the ENG handles the aerial refueling system that pumps gas in flight to the helicopters, and ENG runs the ramp and door for certain airdrops.
NOT an entry level job...at all. I'm over 1,000 hours deep into this job, and I am still learning a lot. We really are the 3rd set of eyes on everything, and the 1st one to catch ANYTHING.
Load-Smashers in the back are very important, but are rarely up on the flight deck. Their world is behind the bulkhead (FS245 on Herks), but no less important.
Feel free to PM me for any more info. I have an Infantry (ARMY), Helicopter avionics and flight line/flight test (ARMY) and FLight Engineer background. I know a lot about what it takes to get going in that world. I am VERY glad I crossed from green to blue. Hit me up any time.
-Doug-