On August 2, 2005, at 1709 eastern daylight time, a Beech 1900D, N136MJ, operated by Colgan Air Inc. as flight 4972 (d.b.a. US Airways Express), was not damaged during takeoff from Knox County Regional Airport (RKD), Rockland, Maine. The certificated airline transport pilot, certificated commercial pilot, and seven passengers were not injured. Visual meteorological conditions prevailed for the flight destined to Augusta State Airport (AUG), Augusta, Maine. An instrument flight rules flight plan was filed for the air carrier flight conducted under 14 CFR Part 121. The captain stated that during the takeoff roll, the first officer called "V1 rotate" at 100 knots. The captain pulled the yoke with both hands, and it did not move. The captain then pulled significantly harder, and the yoke moved quickly aft. The airplane "jumped" into the air, but the captain was able to maintain controlled flight, and elected to continue to AUG. The captain noted that during cruise flight everything was normal except that the elevator trim moved slowly nose up, which required an input of 1/2-unit nose down trim every 1 to 2 minutes. The flight landed uneventfully at AUG about 28 minutes after takeoff. After landing at AUG, the airplane was initially examined by Colgan maintenance personnel. The maintenance personnel noted that the outer portion of the left elevator could be "moved around" by hand. They also noted that transponder wires were contacting the flight control column, and they moved the wires. However, the maintenance personnel could not determine if the transponder wires were related to the anomaly as reported by the captain. The maintenance personnel subsequently removed the left elevator before a Federal Aviation Administration (FAA) inspector or Raytheon Aircraft Company technical representative had an opportunity to examine the elevator on the incident airplane. A Raytheon technical representative subsequently examined the left elevator at Colgan Air's maintenance facility in Hyannis, Massachusetts. Although the incident was not initially reported to the Safety Board, an FAA inspector was conducting routine surveillance at AUG on August 4, 2005, and observed the airplane without a left elevator. The inspector began to investigate further, and learned of the elevator anomaly. He subsequently arranged for another FAA inspector to examine the suspect elevator at Colgan Air's headquarters, in Manassas, Virginia. The re-examination in Manassas occurred on August 22, 2005, and was also attended by representatives of Raytheon Aircraft Company. The re-examination revealed that seven rivets were loose, and one rivet was missing in the vicinity of the left side elevator outer hinge-point attach bracket. During ground tests with an exemplar aircraft, the FAA inspector was unable to duplicate the elevator anomaly as reported by the captain, and could not positively relate the loose rivets to the elevator anomaly. However, a fleet inspection of Colgan Air's Beech 1900s revealed that five of the eleven airplanes had loose rivets on the elevator hinge-point attach brackets. In addition, fleet inspections of other operators' Beech 1900s revealed that some of the airplanes had loose rivets on the elevator hinge-point attach brackets. The airplane was maintained under a continuous airworthiness maintenance program. The airplane's last inspection was performed on July 29, 2005. The airplane had accumulated about 10 hours of operation from the time of the last inspection, until the time of the incident. As a result of the investigation, the FAA issued Airworthiness Directive (AD) 2005-18-21, effective September 13, 2005. The AD pertained to all Beech 1900, 1900C, and 1900D model airplanes. The AD required operators to: inspect all elevator hinge support attachments on both left and right elevators for loose and missing rivets; replace rivets if loose or missing rivets are found; inspect the elevator hinge joints for looseness and clearance of each elevator to its stabilizer; correct looseness and clearance if incorrect; and report results of the required inspections. The suspect rivets and elevator were replaced on the incident airplane, and as of the publication of this report, the anomaly did not reoccur.