On July 20, 2001, at 1515 eastern daylight time, a Cessna U206G amphibian, N756DM, operated by Scenic Seaplanes, Incorporated and piloted by a commercial pilot, sustained substantial damage when it nosed over in a field 5 miles east of Freemont, Michigan, during an emergency landing. Prior to the accident, the airplane's engine lost partial power during cruise flight. Visual meteorological conditions prevailed at the time of the accident. The aerial observation flight was contracted by the United States Forest Service to perform fire patrol under the provisions of 14 CFR Part 135. A company VFR flight plan was on file. The pilot and passenger, a pilot-rated aerial observer, on board the airplane reported minor injuries. The local flight originated at Cadillac, Michigan, at 1400. In his written statement, the pilot said they were proceeding east at approximately 2,500 feet mean sea level when he noticed the manifold pressure had dropped to approximately 30 inches of Mercury (Hg). The pilot said he moved the throttle in and out several times but the power did not change. The pilot said he executed a 180-degree turn toward the Freemont Airport. On completion of the turn, the pilot noticed the manifold pressure had dropped to 15 inches Hg. The pilot looked for a place to land. He said there was nothing in front of them but trees. The pilot then noticed a farm field beneath and to the left of him. He said he decided to put the airplane down in the field. The pilot said he left the wheels and the flaps up because he was "low, slow, and short". He said the farm field was a short one. The pilot said he tried to flare. They hit the ground hard. The pilot said he did not recall the airplane going over its nose and coming to rest on its back. A Federal Aviation Administration inspector examined the airplane at the accident site. The airplane was found resting inverted in a corn stubble field. The left float and legs were bent to the right and resting against the right float. The landing wheels in the floats were in the "up" position. The engine mounts were twisted 35 degrees to the left. The cowling and forward fuselage was crushed aft and twisted left. One of the three propeller blades was bent aft. The other two blades were bent forward. The aft fuselage was bent and buckled. The empennage was broken off. Both wings showed numerous bends and buckles. Flight control continuity was confirmed. An examination of the engine showed the throttle cable broken at the linkage to the throttle box lever arm. No other anomalies were found with the airplane.