On March 25, 2003, approximately 0945 Pacific standard time, an unregistered experimental homebuilt SNS-8 aircraft, owned and being flown by a private pilot sustained substantial damage when the aircraft impacted terrain and nosed over during an off airport precautionary landing following a loss of control in flight near South Prairie, Washington. The pilot was uninjured. Visual meteorological conditions prevailed and no flight plan had been filed. The flight, which was personal, was to have been operated under 14 CFR 91, and originated from Cawley's South Prairie private airstrip (02WA) approximately 0930. The pilot reported that the aircraft had undergone repair work including re-skinning and had been trailered to South Prairie from Oregon on March 24th. The pilot took the aircraft out on its first flight following the maintenance work, departing 02WA and climbing up to approximately 1,300 feet above ground. He reported that when he attempted to level the wings out of the left turn, he could not stop the aircraft from rolling left. The aircraft rolled inverted and the pilot reported that it entered into a spin, which he recovered from after roughly two rotations. Following his recovery he elected to execute an immediate landing in a nearby field and determined that fences and other objects would interfere with the aircraft's landing roll. He then conducted an approach to the field and "...decided to slow to stall speed and ditch at very low alt[itude]...." Upon ground impact the aircraft rolled a short distance and then nosed over (refer to graphic image 1 and 2). An inspector from the Federal Aviation Administration (FAA) interviewed the pilot (refer to attached statement) and examined the aircraft. He reported finding no malfunction with the flight controls and asked the pilot about his airspeed at the time of the spin entry. The pilot responded that the airspeed indicator was inaccurate and that "...he judged his airspeed by how fast the trees were passing by the aircraft...." An operational check of the aircraft's airspeed indicator by the FAA inspector revealed a leak in the pitot static system.