Incident Overview
During an aerial application flight, the low fuel level warning light illuminated. In accordance with the procedures outlined in the airplane flight manual, the pilot started a stop watch. Approximately six minutes later, while en route to a refueling location, the engine ceased operation due to fuel exhaustion.
Landing Sequence
To avoid trees below the intended flight path, the pilot deliberately bled the main rotor rotational speed (rpm). This action resulted in a hard landing.
Post-Crash Examination
Following the accident, fuel was added to the fuel tank. The engine was then started and found to operate normally without any indications of malfunction.
Fuel System Investigation
Subsequent testing revealed that when all fuel was drained from the full tank, the cockpit fuel gauge continued to register a full condition. The gauge would only change its indication if the side of the fuel tank was physically contacted, thereby dislodging the stuck fuel gauge transmitter.
Maintenance Records
The pilot stated that he had previously brought the issue of the stuck fuel transmitter to the attention of the operator. However, a review of the maintenance records showed no entry indicating that the transmitter had been repaired or replaced.
Flight Manual Guidance
Review of the flight manual disclosed that once the low fuel light illuminates, the aircraft should fly no longer than 10 minutes before taking action.