Incident Description
During the takeoff rotation, the captain pulled the yoke with both hands, but 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 continue to the destination airport. 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.
Post-Flight Inspection
Subsequent examination of the airplane revealed that the left elevator could be moved around by hand. Further 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. Ground tests were unable to duplicate the elevator anomaly as reported by the captain.
Fleet Findings
A fleet inspection of the operator's aircraft revealed that five of the eleven airplanes had loose rivets on the elevator hinge-point attach brackets. In addition, fleet inspections of other operators' same make and model aircraft revealed that some of the airplanes had loose rivets on the elevator hinge-point attach brackets.
Corrective Action
The suspect rivets and elevator were replaced on the incident airplane, and the anomaly did not reoccur.