Incident Overview
A pilot was conducting a flight to pick up film for a television station. While en route, the pilot issued a mayday call to the Manchester control tower. According to witnesses, the helicopter was proceeding in a northerly direction at an altitude of approximately 700 to 1,000 feet above ground level when a "muffled pop" was heard.
Observations from Witnesses
The helicopter then entered a descent and banked left toward an open area adjacent to an apartment complex. Several witnesses reported observing the main rotor blades slowing down during the descent. Subsequently, the aircraft crash-landed in a confined area, coming to rest approximately 120 feet from the initial impact point, and then burned. None of the witnesses saw smoke coming from the helicopter before it crashed.
Investigation Findings
Disassembly of the engine revealed that a third-stage turbine wheel blade had failed due to fatigue. No other causal factors were identified in the source.
Conclusion
The accident investigation determined the probable cause to be fatigue failure of a third-stage turbine wheel blade, which led to the engine failure and subsequent crash.