Brazil's regulator, the Agéncia Nacional d'Avição Civil (ANAC), has lifted the temporary grounding order it imposed on Brazilian-registered AgustaWestland AW139s following a fatal accident on 19 August.
In all, 18 helicopters were affected by the grounding order, most of them operated by three air taxi companies.
The incident involved an AW139, registration PR-SEK, flown by Brazilian offshore operator Senior Taxi Aéreo. It failed to return to a Petrobrás oil platform after declaring an emergency mid-flight.
The submerged wreck of the aircraft was later found 100km (54nm) west of the Brazilian coast.
An investigation into the cause of the accident continues.