Md Helicopter 369 N593C accident near Hauula, Hawaii

Probable cause

Fuel exhaustion as a result of the pilot’s fuel burn miscalculation. Contributing to the accident was the inoperative caution light indicating low fuel level.

NTSB analysis

During the fifth flight of the day, while flying about 1,700 ft mean sea level, the pilot noted the engine-out [warning] beeping, the engine-out light, as well as the re-ignition warning light on the caution warning panel. He noted the FUEL LEVEL LOW caution light did not illuminate during the flight. The pilot entered an autorotation and was able to descend to what looked like a more level area. He made a mayday call, flew toward the lowest and most uniform area of trees, and executed a “full down” autorotation. As the helicopter descended through the tree canopy, the helicopter rolled to the right before coming to rest upside down. All four occupants were able to evacuate the helicopter without assistance.

The pilot reported he had 64 gallons of fuel onboard before beginning his flights for the day. He conducted four flights before the accident flight that involved transporting passengers and cargo to different landing zones. He noted he had about 200 lbs of fuel according to the fuel gauge before he lifted off for the fifth flight. He flew three passengers to three different landing zones to deploy equipment before starting toward a staging area to refuel. He stated the fuel gauge indicated 100 lbs of fuel remaining when he lifted off from the final landing zone to fly about 5 minutes to the staging area. The pilot stated that the engine failure was due to fuel exhaustion because he overestimated his shutdown time, underestimated his flight time, and relied solely on the fuel gauge.

Examination of the fuel low warning system found that a wire to a resistor on the sending unit was corroded and separated, resulting in the FUEL LOW LEVEL light being inoperable. Had the pilot been provided information that a low fuel level condition existed, he would have had about 5 minutes to select an emergency landing site, if airborne, or had the opportunity to decide not to depart on the next flight segment.

Text from the NTSB. Open the NTSB docket for WPR19LA111 for the full record.