Damage Description
The airplane returned from a local flight with substantial damage resulting from a crack through its vertical stabilizer spar. The crack is located approximately 6 inches above the base of the vertical stabilizer and extends horizontally approximately 1 1/2 inches from the right side of the stabilizer into the 3 1/2 inch spar.
Inspection History
The airplane was used throughout its service life as a rental/flight training airplane. It and the vertical stabilizer accumulated a total time of 14,155 hours. According to the operator's maintenance personnel, the crack was not present during the airplane's last annual inspection, which was performed 10 hours before the flight.
Preventative Measures
Maintenance personnel had installed a doubler at the root of the rudder as a preventative measure against skin cracks.
Fracture Analysis
Examination of the fracture surfaces were consistent with overstress fractures.