On December 27, 1995, approximately 0952 central standard time, a Stinson ST-108-2, N135C, registered to, and operated by the student pilot under instruction, as a Title 14 CFR Part 91 instructional flight, was destroyed during a forced landing to water following a loss of power after takeoff from a private airstrip, near Lake Dallas, Texas. Visual meteorological conditions prevailed and no flight plan was filed. The pilot-in-command, a certified flight instructor (CFI), received minor injuries and the student pilot was not injured. After practicing takeoffs and landings, the flight departed the airstrip about 2 minutes prior to the accident, and was en route to Addison Airport, Dallas, Texas. The CFI reported the following information: After takeoff, while climbing through 500 feet above ground level, the engine "experienced a dramatic and immediate power loss (70-80%) and began surging, all in the low RPM range." The airplane could not sustain level flight. The student pilot was at the controls when the engine started to run rough; however, the CFI assumed control of the airplane during the emergency descent/landing. He attempted to return to the airstrip, however; "although the engine was still running, it was not developing any appreciable thrust." During the descent, he decided to "ditch under control" in a lake to avoid descending into a residential area. Both occupants exited the airplane after the water landing, and swam to shore. The airplane subsequently submerged. During an engine teardown by the owner, it was discovered that the #6 connecting rod had "failed."