I'm currently experiencing this problem as well. I have only used the helicopter in the showcase and wasn't having problems when I first tried the mission. After exiting and changing my helicopter controls to use W as up, S as down, and A and D as left and right pedal, my helicopter view became stuck in free look. I can access free look normally as infantry and it is off by default (toggled by altx2, accessed with alt), but when I get in a helicopter it is automatically on and unchangeable. If I hit altx2 to toggle free look and then hold alt to disable free look my view is sent to the center of the screen repeatedly. As I move my mouse it moves off the center only to be sent back without controlling the helicopter. Resetting my keybinds to default has had no effect on the problem.

This is happening in the latest version of the full alpha.

Latest patch seems to have fixed this for me. If not that then it was creating a brand new profile, attempting to reproduce the bug (failed), and then returning to my original profile to find the bug was no long present there either.