What happened
The aircraft was engaged in a routine powerline patrol mission when the engine began to surge twice before ceasing operation entirely. With no remaining forward thrust available, the pilot initiated an autorotation maneuver to maintain rotor RPM and control descent rate. The only suitable landing area identified was a high school football field located nearby.
During the final phase of the approach, the helicopter touched down on the grass surface. Upon impact, the main rotor blades flexed significantly due to the kinetic energy of the landing. This flexing caused the rotating blades to strike and sever the tailboom structure of the aircraft.
The investigation
Post-accident examination of the aircraft revealed critical details regarding the fuel system. Inspections confirmed that less than two quarts of fuel remained in the fuel system at the time of the incident. This quantity was insufficient to sustain engine operation, leading directly to the power loss experienced during the patrol.
Findings
The primary factor contributing to this accident was fuel exhaustion. The pilot failed to ensure adequate fuel reserves for the duration of the mission, resulting in an in-flight shutdown. While the autorotation was executed correctly to prevent a more severe impact, the lack of power prevented a controlled landing away from obstacles or terrain constraints, leading to secondary damage to the tailboom upon touchdown.
Safety message
Pilots operating helicopters on extended missions must meticulously calculate fuel requirements, including reserves for contingencies. Regular fuel checks are essential to prevent fuel exhaustion, which can lead to in-flight engine failure and forced landing scenarios with limited options.