KANSAS CITY, Mo. -- An airplane parts manufacturer knew for 20 years that one of its products was causing airplanes to crash but did nothing about it, an attorney for the family of the late Gov. Mel Carnahan said Wednesday.

The part, called a vacuum pump, is at the center of a lawsuit filed against Parker Hannifin Corp., of Cleveland, by Carnahan's widow, Jean, and her three adult children, Russell, Thomas and Robin Carnahan. All four family members were in Jackson County Circuit Court on Wednesday to hear opening statements in the case.

Randy Carnahan, the governor's son and the pilot, also died in the plane crash south of St. Louis, along with the governor's longtime aide, Chris Sifford. The plane crashed Oct. 16, 2000, while Mel Carnahan campaigned for a U.S. Senate seat held by John Ashcroft, now the U.S. attorney general.

Carnahan won the race posthumously and Jean Carnahan was named to the seat, which she lost two years later to Republican Jim Talent.

In an opening statement Wednesday, attorney Gary Robb detailed evidence he said will show Parker Hannifan knew the vacuum pump had caused crashes that resulted in 46 deaths.

In his opening statement, Parker Hannifan's attorney, Wayne Taff, countered the case was not about the vacuum pump failing. He said evidence would show the crash occurred after Randy Carnahan, "through no fault of his own," suffered spatial disorientation, which left him unable to tell where he was going or control the airplane.

Taff and Robb both likened spatial disorientation to the feeling one has after someone spins them very quickly on a chair 30 or 40 times.

Taff said Randy Carnahan's experience would have been made worse by the darkness, rain and wind on the night of the crash.

"(Spatial disorientation) is the most horrifying experience a pilot can experience," Taff said.

Robb said the pump's failure left Randy Carnahan "flying blind" and disoriented on the night of the crash.

Robb played the tape of a discussion between the airport and Randy Carnahan, which included Carnahan saying the attitude indicator had failed and asking for directions.

He also defended Randy Carnahan's piloting skills.

"The evidence will be that Randy Carnahan did exactly what he was trained to do. There was nothing he could or should have done differently," Robb said.

The younger Carnahan reported problems with the primary attitude indicator, also known as an artificial horizon, shortly after takeoff from a suburban St. Louis airport en route to New Madrid. The primary attitude indicator tells a pilot whether the plane is banking and whether the nose is high or low.

The National Transportation Safety Board reported the primary attitude indicator was not working properly when the Cessna 335 crashed in fog, rain and darkness. The board also reported the pumps were most likely functioning at the time of impact.

Taff said he would call experts who would testify that both vacuum pumps on the plane would have had to fail in order for the attitude indicator to fail, as Carnahan reported. He said that a 16-month NTSB investigation found no evidence that the pump failed, nor did the NTSB or the Federal Aviation Administration say the pumps were unsafe or that they required any corrective action.

He also told the jury that in 18 communications between Randy Carnahan and the air traffic controller on the night of the crash, Carnahan never mentioned that he lost vacuum power on his plane, which he would have known from his flight instruments.

"There is no question the primary attitude indicator went out on this airplane," Taff said. "Why did it fail? We'll never know."

The plaintiffs have settled with several other defendants for a combined total of about $2 million. The lawsuit against Parker Hannifin asks for unspecified damages.