On March 29, 2011, about 1630 eastern daylight time, an experimental amateur-built Hrosik Aventura II, N5842, was substantially damaged during a collision with terrain after takeoff from Thunderbird Airpark (2FA5), Crescent City, Florida. The certificated sport pilot sustained a minor injury. Instrument meteorological conditions prevailed, and no flight plan was filed for the flight that departed 2FA5, and was destined for Gator Airfield (3FD4), Minneola, Florida. The positioning flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. In a written statement, the pilot said the purpose of the flight was to position the amphibious airplane at the Sun and Fun fly-in so that it could be offered for auction. He stated that during preflight, engine start, taxi, and takeoff, “everything checked out fine.” The pilot described a full-power takeoff at 5,800 rpm, his rotation speed as 48 mph, and then he “lowered the nose to climb out at 60 mph.” As the airplane reached treetop height, the left wing dipped due to turbulence over the trees, and he perceived a loss of engine power. The pilot said he “put the elevator down” to gain airspeed, but the airplane “nosed over” and struck trees, the ground, and a fence. After the accident, the pilot was unable to stop the engine, as it continued to run. He described the engine running roughly at low rpm, while a witness said the engine ran at a “high power setting” for 2 to 3 minutes after the accident, and before the pilot was able to shut it down. The pilot held a sport pilot certificate with ratings for airplane single engine land and sea. He reported 2,000 total hours of flight experience, 25 hours of which was in the accident airplane make and model. Examination of the airplane by a Federal Aviation Administration inspector revealed no pre-impact mechanical anomalies. A review of the maintenance records revealed that the most recent condition inspection was completed March 21, 2011, and the airplane had flown about 6 hours since the previous inspection, which was 2 years prior. According to the FAA inspector, there was no checklist for the airplane, no placarded V-speeds in the cockpit, and no color-coded airspeed range markings on the airspeed indicator. According to the airplane kit manufacturer, the airplane "wants to fly" at 52 mph, rotation speed is 60 mph, and the standard climb speed is 65 mph. He said, "We hold it on the runway until 55-60 depending on the loading and OAT (outside air temperature) or [pressure altitude]." The stall speed for the airplane was approximately 44 mph with the flaps retracted, depending on aircraft weight and builders' modifications.