Are you new to this game? It's the simplest thing, but no worries. You have to open the activation group menu at the bottom of the screen. Then click on 1 for activation group 1 and 2 for activation group 2. If you're on a PC, you can just click 1 on the keyboard in-game.
Thats wierd, but your not the first to have this problem. Im 100% sure that it is not a problem with the plane as it has gone through many hours of testing. Make sure that the ignition switches are on, that the right magneto switch is on, that the right fuel cock is on, and that you then press the starter for the right engine. Please repport back if youre got it started and thank you for the support!
amazing Plane, i love the detail on it and you actual;ly need some stuff to take off instead of just giving a 100% throttle and take off right away :D. Keep up the great work !!!!