Based on the instructions for the still unreleased Battle Changer Drift triple changer, then heavily modified, but using just Kre-O bricks. Rotor blades become the front spoiler in car mode. You can go from car or helicopter mode to robot mode without any partsforming. My biggest challenges were to find a way to lock the arms in helipcoter mode while maintaining ground clearance in car mode and to slim down and shape the rear end of the car. This is the final version. ROBOT MODE HELICOPTER MODE CAR MODE
Neat! If you swap some of the propeller pieces with their blue equivalents, you could make it a reference Action Master Bumblebee's helicopter pack.
First post updated with final version. Maybe that could be done, I'd have to check if I have the bricks for that! Not sure if the blue would clash with the rest of the figure though.