Incident Overview
A pilot reported feeling vibrations in the anti-torque pedals, followed by a series of loud bangs emanating from the tail section. The pilot initiated a precautionary landing. During the landing roll, while the power was off, the main rotor blades contacted the tail boom.
Post-Accident Examination
Examination of the tail rotor driveshaft assembly revealed that the second tail rotor drive shaft segment had failed. The failure occurred after one bolt from the rear Thomas coupler disconnected. Inspection of the bolt holes showed thread imprints. The missing bolt and its nut were not located.
Technical Details
The tail rotor driveshaft assembly consists of multiple segments connected by Thomas couplers. The rear Thomas coupler's bolt failure led to the driveshaft segment separation, which likely caused the vibrations and bangs reported by the pilot. The subsequent blade contact with the tail boom occurred during the power-off phase of the landing.
No further information on the aircraft type, registration, or operator was provided in the source.