Lawmaker probes oil rig staffing before spill

WASHINGTON (Reuters) - A congressional committee has asked the operator of the Deepwater Horizon oil rig to clarify staffing logs that suggest an absence of key personnel on board prior to the explosion that triggered the Gulf of Mexico oil spill.

"There appear to have been fewer people at work on the rig the night of the explosion than at any time in the preceding two weeks," Representative Nick Rahall, chairman of the U.S. House Committee on Natural Resources, said in his letter which cited reports obtained by his committee's investigators.

The letter, sent to the company on Monday, asked Transocean Ltd, the rig owner operating under the direction of BP Plc, to clarify its staffing logs.

Transocean's drilling crew payroll data, obtained by the committee, showed only 18 employees listed on the noon to midnight shift on April 20, the night of the explosion, down from 28 employees on April 1 and 25 on April 14.

There were no engineers, electricians, mechanics or subsea supervisors on duty during the latter half of April 20, the documents suggest.

For its part, Transocean said the numbers gathered by Rahall's committee did not reflect the actual staffing levels on the rig. It said in a release the "vessel was properly and professionally manned; there was no shortage of technical expertise, nor did any crew member work a 24-hour shift." Transocean said it will provide Rahall with actual hours worked by rig personnel and additional information he requested.

Rahall said an internal BP investigation has pointed to inattentiveness as a possible contributing factor in the explosion that sparked the spill.

"I have serious questions about whether enough people were working..., or if crew fatigue caused by extended shifts may have played a role," Rahall said.

He acknowledged the payroll data could not give a full picture of exactly who was working, and some rig workers have testified to having been on duty at the time of the explosion despite not being on the payroll data.

Transocean could not immediately be reached for comment. The company's shares tumbled to their lowest level in 18 months in New York Stock Exchange trading amid worries about liability for the oil spill.

Transocean shares fell $2.84, or 5.78 percent, to end at $46.33, after sinking as low as $44.05. President Barack Obama said in a televised interview that he wanted to know "whose ass to kick" over the worst ever oil disaster in U.S. history.

According to the payroll data, 28 employees were on duty for the noon-to-midnight shift on April 1, 27 worked on April 2 and 26 consistently staffed that shift from April 3-13.

In the week before the explosion, the shift was staffed by 25 employees on April 14, 23 on April 15-16 and 21 on April 17-19.

(Additional reporting by Matt Daily in New York and Braden Reddall in San Francisco and Timothy Gardner in Washington; Editing by Sofina Mirza-Reid)