On November 13, 2001, at 0920 central standard time, an Aero Commander 200D, N28PC, was substantially damaged when it experienced an airframe structural failure while in cruise flight near Houston, Texas. The airplane was registered to three private individuals and operated by one of the individuals. The commercial pilot, who was the sole occupant of the airplane, was not injured. Visual meteorological conditions prevailed and an instrument flight rules (IFR) flight plan was filed for the 14 Code of Federal Regulations Part 91 personal flight. The flight originated from the West Houston Airport, Houston, Texas, at 0915, and was destined for Mineral Wells, Texas. According to the pilot, he departed Houston and ten minutes had elapsed when the airplane "started vibrating, a little at first, then gradually more." When the airplane starting vibrating, it was flying level at 4,000 feet, at an airspeed of 165 mph, and there was no turbulence. The pilot visually checked the wings and tail surfaces, and observed that the horizontal stabilizer was shaking with more intensity than the rest of the airplane. The vibration continued to intensify to the degree that the flight and engine instruments in the cockpit were unreadable. The pilot declared an emergency to air traffic control and initiated an emergency descent toward the David Wayne Hooks Memorial Airport, Houston, Texas. He then slowed the airplane to 120 knots and the vibration subsided; however, the vibration was still apparent. He added that the elevator control was responsive to control inputs. Subsequently, the airplane landed at the David Wayne Hooks Airport. After the pilot exited the airplane, he observed that the left elevator was hanging 3-4 inches low, at the outboard end. Examination of the airplane by an FAA inspector revealed damage to the elevator and horizontal stabilizer. The outboard left elevator hinge had separated from the horizontal stabilizer. A section of the aft spar had separated from the horizontal stabilizer and remained attached to the elevator hinge. The left elevator trim tab push rod had separated in two places. On September 1, 2001, the airplane underwent an annual inspection, at which time it had accumulated a total of 2,823.4 hours. On October 29, 2001, according to a work order (No. 11061) from Calkins Aero Service, Inc. Houston, Texas, several dents on the left elevator were repaired. The work order stated that the left elevator end cap and balance weight were removed from the airplane, and the damaged areas were repaired. During the repairs, rivets on a portion of the elevator were removed and then replaced while the elevator remained attached to the horizontal stabilizer. The balance weight and end cap were then reinstalled. Caulkins Aero stated that no abnormal stresses were placed on the elevator hinge attachment points during the repairs. The work order revealed that the airplane had accumulated a total of 2,889.0 hours at the time that the work was completed. At the time of the accident, the airplane had accumulated a total of 2,900.0 hours.