Incident Overview
An instructor and student were practicing stall maneuvers when, during a recovery, the instructor heard a loud 'bang' followed by an uncommanded roll to the left. The instructor verified that the aircraft remained under control and conducted a visual inspection, discovering that the left flap was retracted while the right flap was still extended.
Flight and Landing
After unsuccessful troubleshooting attempts, the instructor instructed the student to fly the aircraft back to the airport. The landing was executed without any problems.
Post-Accident Examination
A post-accident examination by the NTSB Materials Laboratory determined that the flap cable had fractured due to fatigue. The cable exhibited signs of fatigue cracking before the final failure.