This video shows you how to get the skull that is hidden in Bad Piggies When Pigs Fly Bonus Level 3-VII. The skull is at the extreme right, near the finish line. Fly your heli-plane along the bottom of the level, but before reaching the checkered flag, use a firework to blast back to the left. The “moustache” skull awaits.
If you have a different strategy for completing this level feel free to leave a comment below.