Original sentence: In the Netherlands, the Dutch govt says that this is probably one of the finest airplanes ever built.On April 14, 2009, the NTSB wrote an urgent letter to the FAA recommending that they ground all Zodiac CH 601 XLs.The FAA told the NTSB to "go pound sand"
Edited sentence: According to the Dutch government, since 2005 'at least seven accidents with Zenith CH601 XL's have happened in which one or both wings have failed'.In the Netherlands, the Dutch government grounded the 12 Dutch-registered CH 601 XLs on October 24th, 2008.On April 14, 2009, the NTSB wrote an urgent letter to the FAA recommending that they ground all Zodiac CH 601 XLs, saying "It appears that aerodynamic flutter is the likely source of four of the U.The NTSB also wrote to ASTM International, the body responsible for developing standards for light sport aircraft, recommending that those standards be changed in light of the investigation.The NTSB says that the type has been involved "in six in-flight structural breakups since 2006".The investigation is on-going.The planes were banned from flying pending an investigation into their structural strength, following the crash of a European variant of the design (Rotax powered and 450 KG MTOW) that killed two people.Zenair Europe has listed all known causes for these accidents  (none are due to a design defect) and, after a first-hand review of the wreckage, now also rejects suggestions that the aircraft in the Dutch accident experienced a structural failure.accidents and of at least two foreign accidents"