GetForwardActor not working after jumping

I need a vehicle that has to move forward, back, turn left and turn right. I works perfect as i update the position every tick.

The forward actor always shows the way i have to go or to move. If i dont turn left or right i have the same linear velocity vector:
ex: 62,41,0 62,41,0…
I can change the direction turnint left or right and it works perfect…

but when i got the instruction “jump”… it gets a mess… and even if i dont turn left or right… it goes moving some kind of circular movement ( increasing x and decreasing y)… just moving forward or backward.
ex: 62,41,0… 63,40,0…64,39,0…65,38,0…

The forward vector isnt pointing in the right direction that it was before…
I cant return to work properly…as i exit the game and begin again… just again it works perfect till i jump…

Ive also read that setphysics is giving problems, but if i replace by addimpulse or ad force it doesnt work…

Thanks in advance and sorry for my bad english…

My code: