What happened
During cruise flight, the pilot reported experiencing a sudden yaw, a noticeable loss of engine power, and a decrease in rotor RPM. Recognizing the severity of the situation, the pilot immediately turned toward the homefield and initiated a descent to prepare for an emergency landing. While en route, the engine lost all power completely. The pilot was unable to prevent a hard impact with the ground, resulting in the helicopter landing forcefully in an open field.
The investigation
Following the accident, investigators conducted a thorough examination of the aircraft's engine to determine the root cause of the sudden power loss. The mechanical inspection revealed that the crankshaft had separated completely. Analysis of the fracture surface indicated that the failure originated from a fatigue crack that propagated through the number four rod journal.
Findings
The investigation concluded that the crankshaft separation was the primary factor leading to the accident. The fatigue fracture at the number four rod journal compromised the structural integrity of the engine, resulting in an immediate and total loss of power. This mechanical failure left the pilot with no option but to perform an emergency landing in the available terrain.