NCAA college rules.

A LB blitzes and has a clear shot at the QB. He hits the QB in the chest with his helmit on first contact. Is this a penalty?

The player doesn't seem to be spearing the QB with his helmit, in that, the player doesn't seem to be exaggerating his movement with his head extended forward. It appears to be a normal tackling motion, but first contact is helmit to QB chest.

Thank You in advance.

It's helmet, not helmit.

You have to see it to say for sure but the fact that the helmet hits first is not enough in itself to justify flagging. If the helmet is used to punish the player, it should be flagged.