On July 12, 2005, about 0815 eastern daylight time, a homebuilt Ultravia Pelican-PL amphibian, N412JP, was substantially damaged during a forced landing, following a partial loss of engine power while departing Middlebury State Airport (6B0), Middlebury, Vermont. The certificated commercial pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local personal flight conducted under 14 CFR Part 91. The pilot stated that he completed construction of the airplane in 1999. The airplane had accumulated about 150 total hours of operation at the time of the accident. In addition, the pilot installed a new Ram Racing Engines EA81, 138-horsepower engine, in March, 2005. The engine was a conversion of a Subaru automobile engine, and had accumulated about 13 hours of operation at the time of the accident. Prior to the flight, the pilot performed a preflight inspection on the airplane, which included a check of both fuel tanks and the gascolator. The inspection revealed approximately 11 gallons of fuel on board, and no water or contamination was observed in the fuel. The start-up, taxi, and takeoff roll were normal except that the propeller rpm was a "bit low" on takeoff. The engine normally operated about 5,700 rpm, with the propeller turning about 2,500 rpm. The pilot adjusted the propeller pitch to increase rpm from 2,000 to 2,500. Shortly after takeoff from 6B0, the airplane experienced a partial loss of engine power, and the rpm dropped to approximately 1,500. Since there was not enough power remaining to return to the airport, the pilot performed a forced landing, straight ahead, into trees. The pilot further stated that he examined the wreckage, and did not find any mechanical malfunctions with the engine, fuel system, or ignition system. The airplane was equipped with a three-bladed propeller that had a controllable pitch (approximately 11 degrees to 22 degrees) via a spring switch and electric motor. The pilot initially believed that the controllable pitch propeller went uncommanded to full cruise pitch during the initial climb. However, he subsequently tested the propeller, and determined that it worked correctly, and was in the "full fine" pitch position at the time of the accident. Examination of the airplane by a Federal Aviation Administration inspector did not reveal any pre-impact mechanical malfunctions.