On May 27, 2000, about 1315 eastern daylight time, a Cessna 172N, N734ZD, registered to American Land Corporation-Charlotte, Inc., experienced a loss of engine power and collided with a power line during a descent for a forced landing near the Lincoln County Airport, Lincolnton, North Carolina. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 instructional flight. The airplane was substantially damaged and the certified flight instructor (CFI) and student pilot were not injured. The flight originated about 1210, from the Lincoln County Airport, Lincolnton, North Carolina. The CFI stated that the student had performed four full-stop landings then departed and remained in the traffic pattern. The student applied carburetor heat during the downwind leg, turned base then final, and when the flight was about midpoint of the runway, the student removed carburetor heat and applied full power. When the flight was over the departure end of the runway, he heard a "pop" sound, the engine began to run rough and was indicating 2,000 rpm. The CFI took the controls, pitched for best glide, and performed the emergency checklist. Attempts to restore engine power were unsuccessful. Unable to return to the runway, he maneuvered the airplane towards a clearing. While descending, the airplane collided with an unmarked power line then a chain link fence and the ground. The student stated that at about the midpoint of the runway, he pitched up to climb, removed carburetor heat, applied full throttle, and "removed one notch to flaps (to the 30-degree level)." He pitched for best climb but "we started to lose altitude." He verified that the carburetor heat was off and the throttle was forward, and noted that the airspeed was at or just above 60 mph. He retracted the flaps to 20 degrees, "but this did not seem to help." He advised the CFI to take control of the airplane, the CFI rechecked the position of the carburetor heat and throttle. He observed that the airspeed was "bouncing" between 40 and 60 knots, and he heard the stall warning system "go off a time or two." At that time he thought the airplane was about 100 feet above the ground, and the CFI then maneuvered the airplane towards a clearing. They both were wearing the seatbelts and shoulder harnesses. Examination of the airplane by an FAA inspector revealed sufficient fuel to sustain engine operation; no contaminants were noted. Additionally the engine controls were connected in the engine compartment. A copy of the statement from the FAA inspector is an attachment to this report. According to the Director of Maintenance (DOM) of the airplane operator, post accident he noted that fuel was leaking from the fuel vent. The airplane was recovered and a compression test of the cylinders was performed, compressions, "...were well above the limits. The magnetos were removed and checked for operation and found to be developing spark." A copy of the statement from the DOM is an attachment to this report. According to the airplane pilot's operating handbook (POH), when performing a balked landing, "...reduce the wing flap setting to 20 degrees immediately after full power is applied." A copy of the excerpt from the POH is an attachment to this report.