What happened
During the takeoff roll, the pilot forced the aircraft off the runway. This action was taken because the pilot mistook a midspan crest on the runway for the departure end of the runway, noting that other similar aircraft had become airborne at that specific point.
This premature rotation caused the aircraft to become airborne in ground-effect; however, the aircraft failed to climb. The aircraft subsequently settled into trees approximately 100 yards beyond the airport boundary. The pilot reported that engine speeds never exceeded 2050 rpm during the takeoff run.
The investigation
Investigation of the engine instrumentation revealed that the tachometer was reading higher than the actual engine rpm. While the instrument indicated 2050 rpm, the actual engine speed was approximately 1650 rpm.
According to the type-certificate data sheet, the engine redline was set at 2350 rpm and the minimum static rpm was 1950 rpm. The pilot had installed the tachometer at some point between the 'Sun 'n' Fun' event in 1996 and November 25, 1996, which was when the aircraft underwent its annual inspection.