See this news account of a just-released report from the Chemical Safety Board: Why Deepwater Horizon could happen again. Of special concern is the fact that the same faulty device is still being used. From the lead paragraph:
A new report investigating the cause of the 2010 Deepwater Horizon disaster says the blowout preventer failed in a different way than previous investigations have concluded.
The U.S. Chemical Safety Board released the two-volume draft report the morning of June 5 and will consider it for approval at a public meeting scheduled for 4 p.m. Central Time June 5 at the Hilton Americas Hotel in Houston.
Update on June 6: From the WashPost, see New report on BP oil spill points to faulty blowout preventer procedures; Investigators says the drill pipe buckled in the first minutes of the Gulf of Mexico disaster.