Incident Overview
On August 21, 2021, at approximately 1330 eastern daylight time, an Enstrom 280C, registration N9285, sustained substantial damage during an accident at Daytona Beach, Florida. The helicopter was being operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported no injuries.
Pilot Account
According to the pilot, the flight was a local trip around Spruce Creek Airport (7FL6) in Daytona Beach. While approaching to land, the helicopter made an uncommanded climb and began to spin to the right. The pilot applied full left pedal input, but the helicopter continued its rightward rotation. The pilot then lowered the collective, resulting in a hard landing on the skids.
Damage Assessment
The hard landing caused damage to the left skid, fuselage frame, and tail rotor blades. The helicopter was substantially damaged.
Postaccident Examination
A postaccident examination revealed that the tail rotor driveshaft was free to spin inside the coupling and was not connected by a through bolt. The coupling and a section of the driveshaft were sent to the National Transportation Safety Board’s Materials Laboratory for further analysis.
Laboratory Findings
The Materials Laboratory examination found that the bolt holes in the driveshaft tube were mechanically distorted, consistent with the application of an axially applied torsional shear stress in the clockwise direction. The fracture surface on the driveshaft tube indicated overstress due to torsionally applied shear stress.