WASHINGTON, D.C. ? BP PLC left the position of senior corrosion engineer for its Alaska operations vacant for 15 months before a leak in one of the company’s pipelines caused a major oil spill on Alaska’s North Slope, according to documents released Friday by the House Energy and Commerce Committee.

Even after the spill, the position went unfilled. “There is an urgent need to recruit and rapidly induct a successor for the vacant senior corrosion engineer position,” said an internal BP audit that was written June 7, three months after a pipeline leak caused the largest-ever oil spill on Alaska’s North Slope.

A BP spokesman in Anchorage said the position remains unfilled, but the company has “qualified people doing pieces of that job.” He also said that BP plans to double the size of its Prudhoe Bay corrosion team.

The House panel launched a probe of BP after the company last month revealed massive corrosion that forced it to curtail production from Prudhoe Bay, the largest producing U.S. oil field.