WASHINGTON (Reuters) - U.S. auto safety regulators are turning to scientists from the NASA space and aeronautics agency for help analyzing Toyota electronic throttles to see if they are behind unintended acceleration, Transportation Secretary Ray LaHood said.

A Toyota Motor Corp car is seen inside the environment testing chamber during a quality control demonstration at its headquarters in Toyota, central Japan, March 30, 2010. REUTERS/Kim Kyung-Hoon

Separate from the work of the National Aeronautics and Space Administration scientists, LaHood said, experts from the National Academy of Sciences will lead a study of unintended acceleration across the auto industry, a broader issue raised by congressional lawmakers at recent hearings on Toyota Motor Corp.

“We are determined to get to the bottom of unintended acceleration,” LaHood said in an interview with Reuters ahead of the formal announcement on Tuesday.

The Transportation Department’s National Highway Traffic Safety Administration (NHTSA) is just beginning its review of Toyota electronic throttles, which have come under heightened scrutiny following the recall of 8.5 million Toyota and Lexus vehicles over the past six months for unintended acceleration.

While the government and Toyota blame mechanical or equipment flaws for the problem, questions have been raised about whether NHTSA over the years adequately handled investigations into motorist and other complaints of possible electronic throttle problems.

The NHTSA review is to be completed by late summer, after which the highway traffic safety agency would then determine whether a formal investigation of Toyota throttles is warranted. Such a probe would set in motion a process that could lead to a recall.

LaHood said the timetable would not likely change unless “something very dramatic” happened with the NASA work.

Other investigations dating to 2004 found no throttle defect, but the National Highway Traffic Safety Administration handled those cases internally.

Toyota, too, has asked an outside engineering consultant, Exponent, to review its throttles, and its preliminary findings have discovered no problems, underscoring Toyota’s steadfast conclusion that its throttle systems are sound.

The Transportation Department inspector general is investigating NHTSA’s and Toyota’s handling of investigations into unintended acceleration. LaHood said the department watchdog would also determine whether NHTSA has appropriate staffing and expertise to handle sophisticated investigations.

Nine NASA scientists would bring expertise in electronics, eletromagnetic interference, software integrity and complex problem solving to the Toyota review, Transportation Department officials said.

LaHood has maintained that NHTSA could handle the analysis itself, but said suggestions from lawmakers at congressional hearings prompted him to consider outside help.

“We’ve used them before. We’ve heard that they may have some influence,” LaHood said of his decision to ask NASA to help.

The National Highway Traffic Safety Administration has teamed with NASA in the past on studies of electronic stability control and airbags.

As part of the Toyota review, NHTSA has purchased the Lexus ES 350 once owned by a Tennessee woman whose testimony before Congress personalized allegations of unintended acceleration.

Rhonda Smith said the luxury sedan suddenly accelerated out of control for six miles while she was headed to Knoxville in October 2006.

An NHTSA investigator could not find any problems and the subsequent owner drove the vehicle for 27,000 miles without any acceleration problems, transportation officials said.

Smith’s vehicle was among the models included in a 2007 Toyota recall of 55,000 floor mats that was carried out several months after the alleged mishap.

Regulators and the company warned that loose mats could be jammed by the accelerator. A second, much larger recall related to floor mats was conducted in October 2009.

The broader industry review of unintended acceleration by the National Academy of Sciences’ National Research Council is expected to take about 18 months.

The National Academy of Sciences, which receives most of its funding from the government, taps expertise from the scientific community and its studies and recommendations are peer reviewed.

NHTSA is also investigating whether Toyota met requirements for providing regulators with recall-related information in a timely way. There is no timeframe for completion of that investigation.