Incident Overview
A helicopter engaged in aerial application work was returning to a private helipad when the pilot observed a warning light momentarily illuminate at an altitude of approximately 40-60 feet above ground level. The pilot attempted to divert to an airport where maintenance facilities were available, but shortly thereafter the engine lost all power. The pilot executed an autorotation landing in a field, during which the main rotor blades and tailboom sustained damage.
Post-Accident Examination
An FAA inspector examined the helicopter following the incident. The inspection revealed that the fuel gauge indicated empty ("E"), and 5 to 7 gallons of fuel remained in the fuel tank. Additionally, the operator reported that an electrical connector had failed in one of the fuel boost pumps.
Manufacturer and Manual Information
A representative from the helicopter manufacturer stated that the specific make and model consumes approximately 25 gallons of fuel per hour. According to the helicopter's manual, "Due to possible fuel sloshing in unusual attitudes or out of trim conditions and one or both fuel boost pumps inoperative, the unusable fuel is ten gallons." This indicates that with the fuel boost pump issue, a significant portion of the remaining fuel might not have been accessible to the engine.
Regulatory Requirement
Review of Federal Aviation Regulation (FAR) 91.151(b) notes: "No person may begin a flight in a rotorcraft under VFR conditions unless (considering wind and forecast weather conditions) there is enough fuel to fly to the first point of intended landing and, assuming normal cruising speed, to fly after that for at least 20 minutes."