Rescue 116 struck rocks before it crashed.
The Air Accident Investigation Unit said in a statement overnight that they found wreckage around the lighthouse on Blackrock Island.
Yesterday, the AAIU made several trips to the 400 metre long island by Air Corps helicopter where they carried out further searches.
It is thought Rescue 116 may have glanced off Blackrock and spun out of control immediately afterwards.
Parts of the tail rotor assembly from the aircraft have been found close to the lighthouse on the island.
It's been one week since the Dublin-based coastguard helicopter came down with four crew on board.
The search continues off the coast of County Mayo for the bodies of Mark Duffy, Paul Ormsby and Ciarán Smith.
Captain Dara Fitzpatrick was laid to rest in Glencullen over the weekend.
It's unlikely that dives off the suspected crash site will take place today due to unfavourable conditions at sea.