Rapoport added that no further proceedings are expected and Brown should wear a new helmet.
The latest complaint was submitted on Monday. The 31-year-old was fighting for the right to a one-year grace period to wear the Schutt Air Advantage, which he has used throughout his career.
He lost his initial grievance to continue wearing the helmet earlier this month.
The helmet is no longer allowed because the NFL follows standards set by the National Athletic Equipment Reconditioners Association, which rules that helmets 10 years or older cannot be recertified.
Schutt stopped making the helmet three years ago, but Brown was one of 32 players still using it last season.