Incident Overview
During a filming operation, the pilot was maneuvering a helicopter at an altitude of approximately 200 feet above ground level (AGL). The pilot reported hearing a loud bang, after which the collective control felt "mushy" and provided "no positive control." In response, the pilot initiated a precautionary power-on autorotative landing.
Landing and Damage
The helicopter touched down on top of a ridgeline and slid an estimated 50 to 75 feet into a gully area, coming to rest with a nose-down attitude of 40 to 45 degrees. During the landing sequence, the main rotor blades contacted and severed the tail boom, causing substantial damage.
Examination Findings
Post-accident examination of the helicopter revealed that the collective bungee support bracket was fractured. A service information notice issued by the helicopter's manufacturer on March 7, 1980, required a one-time inspection of the collective bungee support bracket to ensure that the thickness of the machine web surface in the aft lug area was at least 0.065 inch. The pilot's maintenance records indicated that this service information notice had been complied with prior to June 25, 1997.
However, examination of the fractured bracket showed that the web thickness varied from 0.036 to 0.052 inch, which is below the minimum required thickness. Additionally, a hole that would have been drilled in the bracket during compliance with the service information notice was not present. This indicates that the inspection procedure described in the notice was not actually performed, despite the maintenance records suggesting otherwise.