On September 10, 1999, at 1520 Pacific daylight time, an experimental amphibian Wild Goose A1, N3451, registered to and operated by the pilot as a 14 CFR Part 91 personal flight, experienced a loss of engine power shortly after takeoff from Salem, Oregon. The pilot initiated a forced landing to a river near Keizer, Oregon. During the water landing, the aircraft nosed over. Visual meteorological conditions prevailed at the time and no flight plan was filed. The airplane was substantially damaged. The private pilot and pilot-rated passenger were not injured. The flight had departed from Salem about 20 minutes prior to the accident for a local flight. During a telephone interview and subsequent written statement, the pilot reported that during the cruise climb with full power applied, the engine suddenly experienced a short roughness and partial power loss. The engine then regained full power, followed by a complete power loss. The second pilot set the aircraft's attitude for best glide, while the first pilot applied carburetor heat and checked the engine gauges and fuel controls. The second pilot turned the aircraft toward an open field, while the first pilot continued to try and restart the engine. The engine would not start. As the aircraft continued to descend, the pilots realized that because of obstructions, the airplane would not make the open field. The pilot then diverted to the river. The pilot stated that he was utilizing this aircraft as a land plane, and had not retracted the landing gear after takeoff. During the emergency descent, there was not enough time to hand crank the landing gear up before touchdown on the water. The aircraft touched down on the water with the landing gear extended. During the landing, the airplane nosed over. After the aircraft was recovered from the river, a Federal Aviation Administration Inspector from the Hillsboro, Oregon, Flight Standards District Office, inspected the engine. During the inspection, a fuel line fitting to the fuel pump was found loose. The inspector also noted that the fuel lines were of a non-standard aviation quality/size material.