Thunder Horse PDQ was evacuated with the approach of Hurricane Dennis in July 2005. After the hurricane passed, the platform fell into a 20-degree list and was in danger of foundering. (Video Courtesy of the USCG - United States Coast Guard - July 12, 2005)
The platform was designed for a 100-year event, and inspection teams found no hull damage and no leaks through its hull. Rather, an incorrectly plumbed 6-inch length of pipe allowed water to flow freely among several ballast tanks that set forth a chain of events causing the platform to tip into the water.
The platform was fully righted about a week after Dennis, delaying commercial production initially scheduled for late 2005. During repairs, it was discovered that the underwater manifold was severely cracked due to poorly welded pipes.
The platform took a nearly direct hit six weeks later from Hurricane Katrina but was undamaged.