Helmet comes off Nonrunner
 

If the offense is running the wildcat and the quarterback fakes the dive up the middle but the defense thinks the fullback has the ball. The first defender knocks off the fullbacks helmet and linebackers are closing in.

Since we see that he is not the ball carrier, are we to hold our whistles? Where does player safety figure into this rule?

If a player loses his helmet, he's required by rule to no longer participate in the play. We don't kill this play as that would be an inadvertent whistle. If he participates, we have illegal participation (see 9-6-4g). As far as safety, if he no longer participates but is then forcibly contacted without his helmet on, I have a flagrant personal foul and the player committing the foul will be DQ'd.

Remember also that a player is required to leave for at least one down if their helmet comes off and taking a timeout can't save them, only halftime or OT intermission (see 3-5-10d). The only way they aren't required to come out for a down is if the helmet coming off is directly attributable to a foul. Directly meaning a foul with direct contact to the head or neck area. A block below the waist or block in the back with the helmet coming off still requires the player to leave the game for a down.

Thanks for that explanation
 

Very thorough, thanks for the explanation. Very helpful.

That's the FED answer (although I wouldn't have an automatic flagrant foul for contacting a player without a helmet).

NCAA is slightly different:

Most of it is covered under rule 3-3-9)
Continued participation (beyond the "immediate continuing action") after your helmet comes off is a personal foul on the player who lost his helmet. That player is considered defenseless as a "player obviously out of the play" for purposes of the targeting rule (9-1-4), and any player who contacts the helmetless player commits a personal foul as well.

If the helmet comes off because of an opponent's foul, the player can remain in the game (same as FED). If not, the player CAN remain in the game if his team takes a timeout.

If the ball carrier's helmet comes completely off, the ball is immediately dead.

If a player intentionally removes his own helmet during a play, it's a foul for unsportsmanlike conduct.

Correct my interpretation was FED, not NCAA. I wouldn't either for just any contact, but I specified forcible, and forcible contact against a player without a helmet who is not participating (making himself clearly out of the play) could be considered flagrant, and I probably would. Nothing is spelled out by rule though for this situation, so it's a judgment call. Personally, I would err on the side of safety. You're right though, contact like a standard block using their hands on the helmetless player shouldn't be grounds for DQ and maybe should just be a "talking to."

Agreed.

Non-incidental contact against a helmetless player is going to be a PF at minimum (unless said helmetless player initiates the contact, if he does, that's on him... 9-4-8-L).... and my flagrant threshold is going to be much lower than normal, especially if the contact is anywhere near the head.