Aerospatiale AS350 accident near Starbuck, Washington, October 28, 2016

The NTSB's narrative final · quoted from the NTSB record

The commercial pilot reported that, during the agricultural application flight in the helicopter, the fuel pressure warning light illuminated. The pilot scanned the instruments and noted that the fuel pressure was low and that the fuel quantity was indicating between 40% and 50%. Subsequently, the engine started to lose power. The pilot entered an autorotation and set up the helicopter for landing in the flattest area. Subsequently, the helicopter landed hard, which resulted in substantial damage to the tailboom and main rotor assembly. Postaccident examination of the helicopter revealed that the fuel tank was intact, undamaged, and empty of fuel. Given this evidence, the engine likely lost all power due to fuel exhaustion. Despite the lack of fuel, the fuel quantity gauge indicated that 42% of the fuel was remaining (or about 60 gallons). Disassembly of the fuel transmitter revealed that the float guide pin was separated from the float assembly at the tack weld. The separation of the float guide pin allowed the float to slide down the center torque shaft and prevented the potentiometer drive plate at the bottom from rotating when the fuel quantity changed, which led to the fuel quantity gauge displaying an incorrect fuel level. A review of the airplane's maintenance records revealed that the fuel transmitter was overhauled about 11 months before the accident. Given the evidence, it is likely that, during the overhaul, maintenance personnel improperly welded the float pin guide to its mount and subsequently did not adequately inspect it, which led to its eventual separation from the assembly at the welded area.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.