On March 24, 1992, a Bell 47G-2 (registration N2831B) operated by Sammy D. Goff was involved in an aviation accident near Pikeville, KY. Investigators recorded the probable cause as: The separation of the wood-composed main rotor blade, which was delaminated and contained moisture. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter suffered a main rotor blade separation during landing practice due to delamination and moisture, resulting in a rollover accident with no injuries reported.
What happened
The pilot was conducting practice landings when the aircraft experienced a sudden loss of cyclic control. At the time of the incident, the helicopter was approximately 20 feet above ground level. The canopy shattered upon impact as the helicopter struck the ground and rolled over onto its left side.
The investigation
A post-accident examination of the aircraft revealed that the main rotor blade had separated from the hub. Further inspection of the detached blade showed significant structural degradation. The wood composition of the blade was delaminated, and moisture was found within the material layers.
Findings
The primary factor in this accident was the failure of the main rotor blade due to internal delamination and moisture intrusion. This mechanical failure led directly to the loss of control during the critical phase of landing practice.
Probable cause
The separation of the wood-composed main rotor blade, which was delaminated and contained moisture.