Since we can't customize the Xbox 360 controller scheme which works great (with a few minor annoyances), even doing a complete custom bind can be a hassle, as such with firing the pilot seat's gun.
Currently there is no firing control that I could see for a helicopter, which leaves us stuck with the uncustomizable scheme BHI created, which when firing the gun using the right trigger, causes you to use the right pedal.
It'd be great if there could be a control to fire the turret of a gun in the pilot seat under 'Helicopter Movement' {F20757}