At about 2027 Eastern time, a Piper PA-31-350 was substantially damaged while in cruise flight. The solo airline transport pilot was not injured. Visual conditions prevailed. About 30 minutes into the flight, while cruising at 7000 feet msl on autopilot, the airplanes nose pitched down slightly. The airplane then pitched up slightly, followed by a downward pitch event, resulting in a 200-foot altitude deviation. The pilot disengaged the autopilot, re-leveled the airplane at 7000 feet and re-engaged the autopilot. Several minutes later, the autopilot turned the airplane toward the next navigational fix along the route of flight. About this time, the pilot noticed a vibration in the control yoke, which he described as a “buzzing,” and noticed the airplane was flying in a slight right sideslip. The pilot trimmed the rudder and noted no further vibration. The remainder of the flight was uneventful. Upon landing and exiting the airplane, the pilot noted that the outer portion of the left elevator was bent down, just outboard of the outermost hinge point. Further investigation revealed the outboard-most portion of the elevator forward of the elevator hinge line was deformed downward at an angle nearly perpendicular to its normal position. Additional inspection revealed that the second-most outboard rib was fractured near the hinge line.
