Event Summary
Prior to departure, the captain performed flight control tests and found no abnormalities. The takeoff trim was set to the "middle of the takeoff range" without consulting available pitch trim charts. During the takeoff roll, the pilot attempted to rotate the aircraft twice but aborted the takeoff halfway down the 4,840-foot runway because the controls "didn't feel right." The aircraft continued off the departure end of the runway, through a fence, and came to rest near a road.
Post-Event Inspection
The pilot reported no particular malfunction with the aircraft. Examination revealed that the horizontal stabilizer was positioned at -4.6 degrees, which is the maximum nose-down limit within the takeoff range. The horizontal stabilizer trim and elevator controls were checked and moved freely through their full ranges of travel.
Performance Data
According to the Airplane Flight Manual (AFM) TAKEOFF TRIM C.G. FUNCTION chart, a horizontal stabilizer trim setting of -7.2 degrees would have been appropriate for the calculated center of gravity of 20% MAC. Additionally, Learjet certification testing data indicated that the pull force required at a trim setting of -6.0 degrees (the "middle of the takeoff range") was 33 pounds. With the trim set at the full nose-down position (-1.7 degrees), 132 pounds of force would have been required.
Probable Cause
The official findings state that the probable cause was the pilot's improper trim setting, which resulted in a runway overrun and impact with a fence.