The Air Force’s rate of seeking competitive bids for non-research and development services from the private sector fell significantly behind the rest of the Defense Department between 2007 and 2011, the U.S. Government Accountability Office has concluded in a new study.

That meant that the Air Force missed a substantial opportunity to save taxpayers millions of dollars for purchase of those services, the GAO found.

From fiscal years 2007 through 2011, the rate at which non-R&D services were competed held steady across most of the Defense Department, going from a collective 79 percent in 2007 to 78 percent in 2011, the GAO reported.

But during that time, the Air Force’s rate of seeking competitive bids fell from 75 percent to 59 percent.

The Air Force did not publicly respond to the report, which was released Thursday, but the Air Force is looking into what happened, the GAO said.

The GAO is the investigative and accounting arm of Congress.

The Department of Defense also is taking specific steps to increase competition for contracts, the report said.

“Competition is a cornerstone of the federal acquisition system and a critical tool for achieving the best possible return on investment for taxpayers,” the GAO said in a letter accompanying the report to the House and Senate Armed Services committees.

“Competitive contracts can help save money, conserve scarce resources, improve contractor performance, curb fraud and promote accountability,” the GAO added.

Congress has already asked the GAO to do a follow-up report that will be due in March 2013, Michele Mackin, interim director of the GAO team that did the report, said Friday.

The report did not estimate how much the Air Force’s poorer rate of seeking competitive bids would have cost taxpayers. That would be difficult to determine because many different contracts were involved, including multi-year deals awarded years earlier with continuing spending obligations, Mackin said.

The report examined purchasing on a service- or department-wide basis, not base by base. Wright-Patterson Air Force Base, as the hub of Air Force acquisition and logistics, is a major awarder of contracts.

The Defense Department and Office of Management and Budget have urged all government agencies to promote competition in procuring goods and services, the GAO noted.

U.S. law generally requires federal agencies to award contracts using full and open competition.

But the law allows exceptions — that require written justification — when only one contractor is available to provide a specific service or product, or where there is an urgent need that precludes adequate time for competition.

Contact this reporter at (937) 225-2242 or jnolan@DaytonDailyNews.com.