Incident Overview
A commercial pilot was conducting his fourth landing of the morning. The aircraft touched down on the main landing gear as planned, and the pilot then allowed the tail wheel to contact the runway. Immediately after the tail wheel touched down, the pilot felt a vibration. He responded by lifting the tail wheel back off the runway. Following this action, he lost control of the aircraft, which subsequently ground-looped.
Investigation Findings
Post-incident examination revealed two maintenance issues. The tail wheel bearing and pivot were found to be worn. Additionally, the right rudder brake pedal return spring was discovered separated from its attachment bracket. These findings were noted during the investigation.
Sequence of Events
The pilot executed a normal touchdown on the main landing gear. The subsequent tail wheel contact was followed by a vibration, prompting the pilot to raise the tail wheel. After the tail wheel left the runway, directional control was lost, resulting in a ground loop. No other factors were reported.