What happened
During the takeoff roll on a 4,840-foot runway, the pilot of a Learjet attempted to rotate the aircraft twice before deciding to abort the takeoff. The decision to stop the flight was made approximately halfway down the runway because the flight controls did not feel correct to the pilot. Following the aborted takeoff, the aircraft exited the departure end of the runway, passed through a fence, and eventually stopped near a nearby road. There were no fatalities or injuries reported following the incident, and the pilot did not identify any specific mechanical malfunctions during the event.
Prior to the departure, the crew had performed tests on the flight controls and found no abnormalities. The takeoff trim was configured to what the pilot described as the middle of the takeoff range, though this setting was not verified against any available pitch trim charts.
Findings
Post-incident inspections of the Learjet revealed that the horizontal stabilizer was positioned at -4.6 degrees, which represented the maximum nose-down limit available within the takeoff range. While the elevator and horizontal stabilizer trim controls were found to be functioning correctly and moving freely through their full range, the trim setting was found to be incorrect for the aircraft's weight and balance.
According to the aircraft's takeoff trim C.G. function chart, a setting of -7.2 degrees should have been used given the calculated center of gravity of 20% MAC. The investigation noted a significant discrepancy in control forces: while certification data indicated that a trim setting of -6.0 degrees would require 33 pounds of pull force, the actual setting used required 132 pounds of force. The incorrect horizontal stabilizer trim setting was the primary factor affecting the aircraft's handling characteristics.