so we have late hit the helmet or a ball carrier, he falls down with his helmet on but when he hits the ground it comes off. He can't stay in the game because him being hit on the helmet is not a foul
or we have a late hit on the chest of the ball carrier right after he stepped OB and the hit goes up and touches the facemask while the ball carrier is going down with his helmet. Once he hits the ground, it comes off.
He can be in the game, even though it was a penalty but it was not responsible for the helmet comming off. Even though it was, since the hitter touched the facemask and made it lose enough so it would come off when he hit the ground