They should automatically be there Unless you set a keybinding with multiple vehicles loaded. in my experience that erases all keybinds for all spawned vehicles :|
Huh, I think that's what I did a while ago, I changed the keybindings for the helicopter mod while having the AN-12B spawned in. And then at one point I reset all keybindings to default so that also might've done it...
I have a stupid question: How could I make control surfaces on the plane DO automatically center while using keyboard controls In Flight Simulator X or FlightGear.