The cause of the airplane crash that killed Governor Mel Carnahan and two others is being disputed in court in Kansas City. Arguments in the Carnahan family’s lawsuit against the manufacturer of an airplane vacuum pump have begun. The family says the vacuum pumps failed, cutting off power to several instruments including the one that tells the pilot how the airplane is positioned in relation to the ground. The company that made the pumps says a long federal investigation shows the instrument failed on its own, for unknown reasons.