Helicopter Engine Turbine Failure Results in Autorotation Landing (N7981J)

What happened

The aircraft was operating at an altitude of approximately 200 feet above ground level when the engine suddenly lost power. The pilot immediately initiated an autorotation to maintain rotor RPM and control descent rate. During the maneuver, the pilot actively steered to avoid nearby trees and successfully touched down in a logging clear-cut area characterized by numerous tree stumps.

The investigation

A mechanical examination of the engine revealed that the first-stage turbine wheel had suffered a catastrophic failure. This component exited both the engine casing and the airframe structure, breaking into more than two pieces. Investigators were unable to recover the fragments of the failed wheel, which prevented further metallurgical analysis.

Findings

The investigation determined that the first-stage turbine wheel failure was the primary mechanical event leading to the loss of power. The specific mode or root cause of this wheel failure could not be determined due to the unrecovered nature of the component parts. The pilot's decision to enter an autorotation and maneuver away from obstacles allowed for a survivable landing despite the severe mechanical failure.