Apparently, the Deepwater Horizon oil rig wasn’t Transocean Ltd.’s only troubled platform in the Gulf of Mexico. According to a New York Times report, a month before an explosion sunk the Deepwater Horizon and spawned the BP oil spill, a team of investigators from Lloyd’s Register found serious problems on it and three other rigs owned by Transocean.

The other rigs involved in the investigation were the Development Driller II, the Marianas, and the Discoverer Clear Leader. Ironically, evelopment Driller II is being used to drill one of the two relief wells near the Deepwater Horizon site, while Discoverer Clear Leader is now being used for oil containment there. The Marianas was the original rig on the site of Deepwater Horizon before being damaged in a hurricane, the Times said.

Lloyd’s investigators who visited the four rigs in March concluded that many crew members and front-line supervisors were too readily promoted without sufficient on-the-job experience to appreciate hazards, The New York Times said.

Investigators also found that Nearly 40 percent of workers interviewed on the four rigs said that past problems were typically investigated by company officials strictly to attribute blame. About 43 percent of workers on the four rigs expressed fears of reprisals for reporting problems, with about 54 percent of Deepwater Horizon workers citing such fears.

Documents reviewed by the Times also point to safety problems with the ballast system on Deepwater Horizon that could point to a reason for its sinking after the blast. Finally, the documents also show the severity of the maintenance issues that plagued the Deepwater Horizon, and indicate that Transocean personnel knew what their consequences could be.

The documents refer to at least 36 pieces of equipment in poor repair on the Deepwater Horizon that “may lead to loss of life, serious injury or environmental damage as a result of inadequate use and/or failure of equipment.” They also refer to an inspection of Deepwater Horizon that was conducted just before the disaster that found various problems with hydraulic relays that controlled the rig’s watertight doors, two of which had to be opened and closed by hand, the Times said.