WPR17LA014

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.

On October 28, 2016, about 1240 Pacific daylight time (PDT), a Eurocopter S.N.I.A.S. AS350B helicopter, N369BD, sustained substantial damage during a forced landing following a loss of engine power near Starbuck, Washington. The commercial pilot was not injured. The helicopter was registered to a private individual and operated by Leading Edge Aviation LLC under the provisions of Title 14 Code of Federal Regulations Part 137 as an aerial application flight. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight. The flight originated from a nearby staging area at 1137. The pilot reported that during the flight as he was making his 6th pass, on the 5th application load, and traveling upslope from the west to the east, the fuel pressure warning light illuminated. The pilot scanned the instruments and noticed the fuel pressure was low, and the fuel quantity was indicating between 40-50%. About 3-4 seconds later the engine started to lose power. The pilot entered an autorotation and set up for a landing in the flattest area he could find in the canyon. During the approach the pilot extended the landing to make it to a more suitable site. The helicopter subsequently landed hard. The helicopter sustained substantial damage to the tailboom and to the main rotor assembly. During the recovery it was noted that the helicopter fuel tank was intact, undamaged and void of fuel, but the fuel quantity gauge still indicated 42% fuel remaining, which converts to about 60-gallons.The helicopter was recovered from the accident site for further examination. Examination of the fuel transmitter revealed that the float guide pin was separated from the float assembly at the tack weld. According to the manufacturer, the separation of the float guide pin would allow the float to slide down the center torque shaft and not allow the potentiometer drive plate at the bottom to rotate with changing fuel quantity. Maintenance records for the overhauled fuel transmitter stated that the float guide was replaced at the time of overhaul on November 23, 2015.