MD-80 Series (DC-9-80) Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Aircraft Equipment Problem Critical
Flight Crew Returned To Gate; Flight Crew Rejected Takeoff; General Maintenance Action
Human Factors; Procedure; Aircraft
No abnormalities found on preflight. No abnormalities found on the standardized checklist items when performed and completed. Taxi for departure was uneventful. On the takeoff roll; all calls and checks were uneventful. Approximately 110 knots to 120 knots; First Officer (PF) noticed nose coming up. First Officer pushed nose forward. No change in the pitch rate when full forward pressure was applied to the yoke. I called for abort and verbally called for 'my controls'.  Positive transfer of controls were completed. First Officer completed his duties as required by a RTO.  ATC was notified; Flight Attendants were notified and the passengers were given an announcement of the issue at hand as required. All checklists were completed.We taxied to the ramp without further abnormalities. Brake temps were rising and a tow into the gate was requested and completed. We checked the bag loads and they were in compliance with the count on the weight and balance manifest. We were met at the gate by the mechanic on duty along with his colleague. Maintenance checked and verified that the exterior control surfaces were in alignment with the flight deck settings on the CG; flaps and slats. They then did a control check on the empennage and the mechanics informed us that the left elevator was stuck in the up position.  We also confirmed this finding. A logbook entry was made in the logbook. Flight crews were de-briefed and the duty pilot was contacted.
Reporter states that the rejected takeoff was initiated with the nose wheel well off the ground and continuing with the yoke full forward. Maintenance found that the elevator was jammed by an elevator actuator that had become separated from the elevator due to a missing castle nut. The nut had last been removed and installed by company maintenance during a maintenance check at company maintenance facilities. The reporter believes that had the aircraft become airborne; a serious accident would have resulted.
MD80 Captain reports rejecting a takeoff at 120 knots when the aircraft begins to rotate on its own. The yoke was full forward with the pitch rate increasing when the Captain assumed control and initiated the reject. Left elevator was found jammed in the full up position by Maintenance.