On July 3, 1984, an Enstrom F-28A (registration N13CM) was involved in an aviation accident near Muncie, IN. Investigators recorded the probable cause as: The failure of the tail rotor drive shaft, which resulted in the loss of directional control and necessitated an autorotation landing. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter pilot entered autorotation after the tail rotor drive shaft failed during a left bank at low airspeed, resulting in a controlled landing with minimal forward speed.
What happened
The pilot was operating a helicopter when the aircraft experienced an uncommanded rotation to the right while maintaining a twenty-degree left bank and an airspeed of approximately forty knots. In response to this loss of directional control, the pilot initiated an autorotation maneuver. The helicopter touched down with a forward speed of about five knots.
The investigation
A post-accident examination of the aircraft revealed that the tail rotor drive shaft had failed during operation. Maintenance records indicated that the failed component had accumulated approximately 1314 flight hours prior to the incident.
Findings
The failure of the tail rotor drive shaft was the primary mechanical issue identified. The pilot's decision to enter autorotation allowed for a controlled landing despite the loss of anti-torque capability.
Probable cause
The failure of the tail rotor drive shaft, which resulted in the loss of directional control and necessitated an autorotation landing.