The A models I flew definitely only had a single 3 position switch marked INV with MAIN OFF SPARE from top to bottom, when in the OFF position the AC system was de-energised and in either of the other 2, the selected inverter supplied power to the 115V and 26V bus bars. Both static inverters were capable of the same loads but normally power was supplied by the main while the other carried the loads in case the MAIN inverter failed. The system was 115/26V-400 Hz mono phase type. I think Charlie is spot on about the quill drives and it is the wide body version which incorporated different doors which I think was initially modified to accom the medevac fit so they may well have changed the electrics a bit to accommodate the AC extra loads. It also gave the corporate ones a slightly bigger cabin.
It's looking good, the veritair/Tiger one I was talking about was (I think) certified as a FNPT Flight and Navigation Procedures Trainer and without actually moving was good for learning procs prior IR.
Good luck.
Last edited by MOSTAFA; 15th Jun 2016 at 06:39.