What happened
The pilot was operating a helicopter at an altitude of 120 feet above ground level with the auxiliary fuel pump engaged. During this phase of flight, a total loss of power occurred unexpectedly. In response to the engine failure, the pilot initiated an autorotation maneuver. However, the subsequent landing was hard, causing the main rotor blades to strike and sever the tail boom.
The investigation
Post-accident examination focused on the fuel system components. Investigators collected a fuel sample from the chamber of the engine fuel pump filter. Laboratory analysis of this sample revealed the presence of several different types of contamination particles. Further inspection identified that some of these particles originated from a deteriorating bushing within the fuel pump itself.
Findings
The sequence of events indicates that mechanical failure within the fuel system led to the power loss. The deterioration of the fuel pump bushing introduced debris into the fuel supply, which likely caused an obstruction or malfunction in the engine's operation. This mechanical issue resulted in a total loss of power, forcing the pilot to execute an emergency landing procedure that could not prevent structural damage to the aircraft.
Safety message
Regular inspection and maintenance of internal fuel pump components are critical to preventing particulate contamination from entering the engine system. Monitoring for signs of bushing wear can help avoid sudden power failures during flight operations.