On June 16, 1999, about 1515 Eastern Daylight Time, a Cessna 172L, N7897G, was substantially damaged during a forced landing at the Millinocket Municipal Airport, Millinocket, Maine. The certificated commercial pilot was not injured. Visual meteorological conditions prevailed and no flight plan was filed for the aerial observation flight conducted under 14 CFR Part 91. The pilot stated in a telephone interview that after takeoff from Runway 29, the airplane climbed to 400 feet above the ground, when the engine quit. The airplane began to descend and the pilot configured the airplane for a forced landing. Looking for a place to land, the pilot turned the airplane to the right to avoid a residential area located off the departure end of the runway. The airplane was slipped to increase the decent, in an attempt to land on the overrun area of Runway 34. The airplane touched down in a grass field located off the departure end of Runway 34, bounced once and continued into a wooded area. Both wings were damaged, and the left fuel tank was ruptured. Examination of the wreckage by a Federal Aviation Administration Inspector revealed no evidence of mechanical malfunctions or failures with the airplane. An undetermined amount of fuel was observed in both wing tanks. All fuel and oil filters were intact and no contaminants were observed. The spark plugs were removed; their electrodes were intact and light gray in color. The left and right magnetos were tested, by rotating the engine, and produced spark on all leads. The airplane's engine was then prepared for a test run, and started. The engine ran for about 7 minutes, then was shut down. The winds reported on the airport, at 1453, were from 310 degrees at 9 knots.