The combination of CTRL+Shift+F1 switch off all engines in the rest of aircrafts.
Well, not exactly. It shuts down the fuel flow valves, which will result in the engines stop running, of course...
I have not tried to press CTRL + Shift + F1 when the aircraft is with engines running, I only have tried it in cool & dark, and GSX still doesn't work.
That might be the issue.
I have post the same issue in Majestic Software Forum, you can follow it here:
That's the only place were you can get a meaningful solution. The REAL issue is, that airplane uses a custom flight model so, it's running its own internal simulation of things, and most likely even the engines are internally simulated.
But since it's STILL an FSX add-on product, not a stand-alone product, what they should have done, in order to make it fully compatible with FSX and all the countless of 3rd party add-ons, they should have programmed their internal simulation to REACT to FSX Events, and acts accordingly.
For example, if you press the FSX fuel shutoff valves, they should intercept the event and turn off their own internal simulation of them. Or, if you freeze the sim, they should intercept the event and freeze their own internal flight model too.
We tried to to make it even easier for them, and added a variable that would allow them to check if GSX is pushing, but so far, they haven't updated the airplane to make use of it, although it should be a very easy change.