Football: When is a Player Down After a Ground Contact?

Question
if a players arm hits the ground before a fumble is he considered down? Is it any part of the body?

Answer
Bill
For a runner to be down, it is any part of his body other than his foot or hand.  In your question your question you indicate the arm touches the ground. Technically the runner is down, but if you are talking about the hand and wrist part - not the entire forearm or entire  arm I'd say I need to see the play but if an official did not rule a player down because it was the had and wrist, I'd say likely that was a correct call.  But if a player hits the ground, if his arm hits the ground and the ball pops out, it is not a fumble, the player is deemed down.  For forward progress it is the position of the ball when the ball becomes dead.
I hope this helps
Victor Winnek
NCAA Football Official