On September 2, 2007, at 0915 mountain daylight time, a Werner Vari-Eze homebuilt experimental airplane, N547DB, was substantially damaged during a forced landing near Tooele Municipal Airport (KNB), Tooele, Utah. The private pilot, the sole occupant in the airplane, was not injured. The pilot/owner was operating the airplane under 14 CFR Part 91. Visual meteorological conditions prevailed for the personal, cross-country flight that originated from Kanab, Utah, approximately one hour before the accident. No flight plan had been filed. The pilot said that he preflighted his airplane and departed Kanab, with another airplane (a flight of two), at approximately 0818. He said the flight was uneventful but for deviating east of their planned course for thunderstorms. During their descent to Tooele Municipal Airport, they noticed a large thunderstorm over their destination. The other pilot elected to land. He radioed the pilot and said "it was very bumpy, but thought I could handle it." The pilot said he got into severe turbulence on final and elected to go-around. His second approach also terminated with a go-around. During his third approach he had a total loss of engine power. He turned the airplane towards the airfield, but encountered "severe wind shear (down draft)." He picked a field for a forced landing, but he encountered another down draft. During his landing flare, the airplane's main landing gear impacted a ditch and separated from the fuselage. Photographs of the wreckage indicate that the outboard right wing skin had delaminated from the spar and both wing root areas exhibited visible cracks in the upper wing skin. An aerospace engineer from the National Transportation Safety Board said the cracks above the main spar carry through structure indicate hidden damage in the spar. A Federal Aviation Administration inspector and the pilot examined the airplane in the field. They identified no abnormalities with the engine; the reason for the loss of engine power was not determined.