USN/USMC:
At squadron level ("O" for organization) the avionics guys are generalists, trained mainly to quickly diagnose and change out LRUs, and to find & repair wiring harness problems.
At the next level of maintenance ("I" for intermediate), we were trained on specific systems or related groups of systems - I was trained on the FLIR/l a s e r systems, other guys were trained on radios, others on navigation systems, or ECM, or radar - etc. There was an IMA (Intermediate Maintenance Activity) at each base, and we deployed personnel with squadrons when they went elsewhere for more than a couple of weeks. The IMA avionics shops were in ISO containers - airconditioned/heated, with the test benches inside -so we could fix LRUs "in the field". In 1984 we packed all of them up and flew them from MCAS Iwakuni, Japan to NAS Cubi point, P.I. for 6 weeks (thank you, USAF C-141s), then brought them back - this was a normal evolution.
"I" level techs frequently went over to the squadrons to help with an unusually nasty problem, or to help out during high-tempo operations, or just to "see how the other half lived". This was particularly true aboard ship or when deployed overseas.
Both of these were, of course, staffed by military personnel (except for an occasional civilian "tech-rep" (technical representative), either from the manufacturer of a high-value system or a government-employed rep from NAVAIR.
Depot level maintenance was usually civilian contractor work with a minimal military staffing "for oversight".
The Hair Farce
worked a bit differently, with more personnel at the squadron level - these were more specialized than in NAVAIR - often requiring 3-4 personnel to perform a task the USN/USMC would use 2 for.
For example, in NAVAIR avionics techs were permitted to remove/replace access panels themselves, in the AF an airframes person had to do that part - NAVAIR avionics techs could apply electrical power to the aircraft to run up the systems, AF avionics guys had to get a aircraft electrician, and so on.
I believe that USAF squadrons also have people specialized in systems - or they used to. Nowadays, the "smart planes" pretty much diagnose themselves, all you need is someone who can remove/install the boxes and deal with the wiring/databus.
http://m.carolinacoastonline.com/art....html?mode=jqm
http://www.dvidshub.net/image/564241...an#.T-4JwZHYHf
