PHOENIX — NFL owners approved two rule changes Tuesday to enhance player safety. They might not vote on a proposal to ban offensive players from using the crown of their helmets against defenders.

The owners outlawed peel-back blocks anywhere on the field; previously, they were illegal only inside the tackle box. A player makes a peel-back block when he is moving toward his goal line, approaches an opponent from behind or the side, and makes contact below the waist.

The penalty will be 15 yards.

Also banned is overloading a formation while attempting to block a field goal or extra point. Defensive teams can now have only six or less players on each side of the snapper at the line of scrimmage. Players not on the line can’t push teammates on the line into blockers, either.

The alignment violation is a 5-yard penalty. The pushing penalty is 15 yards for unnecessary roughness.

But the potential change that has drawn the most attention — yes, even more than eliminating the infamous tuck rule, which seems to be a foregone conclusion — is prohibiting ball carriers outside the tackle box from lowering their helmets and making contact with defenders with the crown.

New York Giants owner John Mara, a member of the competition committee that has recommended the change, expressed doubt Tuesday that the proposal would be voted on before Wednesday, when the owners meetings conclude. He also said there was “a chance” it could be tabled until the May meetings in Boston.

“There was a spirited discussion,” Mara said. “We’ll have more discussion today.”

Many coaches have said they are concerned about officiating such a new rule.

“In all fairness it’s going to be tough on the officials, it’s going to be tough to make that determination at live speed with one look,” said John Harbaugh of the Super Bowl champion Baltimore Ravens.

Harbaugh noted that in the competition committee’s examination of one week of play last season, it found five instances where a ball carrier was not protecting the ball or himself and lowered his helmet to make contact with a defender.

Dean Blandino, recently promoted to vice president of officiating, noted that five in 16 games was significant enough to consider banning the act.

Added Rams coach Jeff Fisher, co-chairman of the competition committee:

“We want to make a serious attempt to get the shoulder back into the game. We are not saying the ball carrier cannot get small. We are not saying the ball carrier cannot protect the football, because if he is going to go down to cover the football, if the shoulder goes down, we know the head goes down, we understand that.

“Protecting the football is OK, providing you do not strike with the crown of your helmet, and that is what we are trying to differentiate.”

Blandino added that the league wants flags thrown only on the obvious calls. He also said in cases where a player is not penalized, he could still be subject to a fine if video review after the game determines he made contact with the crown.

The penalty will be a spot foul for 15 yards.

New senior director of officiating Alberto Riveron said if the offensive and defensive player are both committing the foul, it would be an offsetting penalty and the down replayed.

Riveron said the key to officiating the play is in showing the officials more plays that are legal.

“That will be a great way to train because as we know it, most of the shots we have seen are legal, most of the contact is legal,” he said. “We are trying to get that one individual situation where the head is lowered — and you can see on the field, you can see a player put his head down — and the contact is with the crown and you can see it.”

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