Law enforcement sources tell TMZ, DCFS experts closed their investigation involving an incident between Brad and his adopted son Maddox on board a private plane in September (16).

The alleged altercation prompted Pitt's wife Angelina Jolie to file for divorce four days later, but DCFS officials have ruled the actor did not commit child abuse during the reported argument.

Social workers have been interviewing the former couple and its six kids, as well as eye witnesses and staffmembers for weeks to get to the bottom of the alleged fracas.

The DCFS ruling gives Brad an edge in his custody battle with his estranged wife, who is asking for sole physical custody of the couple's adopted and biological kids. Brad wants joint custody.