The National Transportation Safety Board (NTSB) has issued an urgent safety recommendation asking FAA to disallow flights of the Zodiac CH-601XL, which has experienced six in-flight structural breakups since 2006. Designed by Senair, the two-seat light sport aircraft (LSA) was involved in four accidents in the U.S. and two in Europe that resulted in the deaths of 10 people. A suspected factor in all of the crashes is aerodynamic flutter, a condition where the control surfaces of an aircraft can suddenly vibrate, potentially leading to structural failure. FAA certified the Zodiac in 2005. NTSB is recommending that FAA ground all CH-601XLs until the agency can determine that the aircraft are not susceptible to aerodynamic flutter. Safety board investigations of the four U.S. crashes point to a design flaw in the flight control system. Investigators also found that the stick force gradient was not uniform throughout the range of motion, as well as problems with the airspeed indication system. Noting that NTSB rarely recommends such a measure, Acting Chairman Mark Rosenker says in the case of the CH-601XL, “we believe such action will save lives. Unless the safety issues with this particular Zodiac model are addressed, we are likely to see more accidents in which pilots and passengers are killed in airplanes that they believed were safe to fly.”
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