Antonio Brown may have returned to the Oakland Raiders’ team facility on Monday after a brief holdout, but his helmet saga isn’t over just yet.

Brown filed a second grievance against the NFL in his battle to wear his old helmet on Monday, according to ESPN’s Adam Schefter.

According to the NFL Network’s Ian Rapoport, Brown’s new grievance claims that the NFL is “arbitrarily applying rules,” and argues that he should be afforded a one-year grace period to phase out his helmet. It also argues that the “NFL is unreasonably exercising its management rights.”

His new grievance is expected to be heard by an arbitrator on an “expedited basis.”

Brown has attempted time and time again to wear his old Schutt AiR Advantage helmet with the Raiders this fall, the helmet he has worn throughout his nine-year NFL career. That 12-year-old model, which Schutt no longer makes, has since been deemed unsafe by the league and was phased out this offseason — something the league informed its players over a year ago that it was going to do. The National Operating Committee for Standards and Athletic Equipment, or NOCSAE, won’t certify any equipment over 10 years old, either.

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Brown already lost his initial grievance against the league earlier this month in an attempt to wear that helmet, and the NFL Players Association joined the league in saying that Brown’s helmet is too unsafe for him to keep using. He has since claimed that he’s the victim of “Super Prejudice” and even held out of practice on Sunday because of his helmet. That elicited a very blunt response from Raiders general manager Mike Mayock.

“At this point, we’ve pretty much exhausted all avenues of relief,” Mayock said Sunday. “So, from our perspective, it’s time for him to be all in or all out … We’ve got 89 guys busting their tails. We are really excited about where this franchise is going. And we hope AB’s going to be a big part of it starting Week 1 against Denver.”

The NFL and NFLPA announced last year that there are 24 helmet models acceptable for players to wear, 11 of which are made by Schutt. While it’s easy to understand why Brown wants his old helmet — it’s what he’s used to — there are plenty of helmets out there that are statistically safer for players. Longtime Seattle Seahawks wide receiver Doug Baldwin made the switch to a VICIS helmet late in his career, which reduced impact forces on the head by 30 to 40 percent compared to Brown’s old model.

So even though it once looked like it was over, Brown’s saga to wear his old, unsafe helmet isn’t done yet — and he appears willing to keep on fighting.

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