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Accident Report Detail

​Collapse of the U.S. Mobile Offshore Drilling Unit Penrod 61

Executive Summary


On October 27, 1985, the U.S. mobile offshore drilling tmit PENROD 61 was drilling for oil at an offshore drilling site about 25 nautical miles (nmi) south of the Louisiana coast·in the Gulf of Mexico. The PENROD 61, a self-elevating type drilling unit, was in the jacked-up mode in about 246 feet of water and was elevated about 50 feet above the surface of the water on three bottom bearing legs. About 2330 c.s.t. in seas reported to be in excess of 30 feet high and in winds gusting to 80 knots, the PENROD 61 collapsed into the sea. The 43 persons on board abandoned the vessel and all but one were later rescued. After it fell into the sea the PENROD 61 drifted with the wind and sea, struck the nearby PENROD 60, and subsequently sank about 9 nmi northwest of its drilling site. As a result of this accident the PENROD 61, valued at $40 million, was destroyed and one man lost his life.

Probable Cause


The National Transportation Safety Board determines that the probable cause of the collapse of the PENROD 61 was a structural failure of undetermined origin to its bow leg. Contributing to the collapse of the PENROD 61 was the failure to inspect the legs of the MODU over their entire lengths. Contributing to the loss of life was the failure of the survival capsule· to right itself after capsizing.

Accident Location:   , LA   Gulf of Mexico
Accident Date: 10/27/1985
Accident ID: DCA86MM005

Date Adopted: 9/16/1986
NTSB Number: MAR-86-10
NTIS Number:  

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