Bell 206B accident near Dallas, Oregon, November 2, 2015

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

The commercial pilot of the helicopter reported that, after he released the external load of trees in the loading zone and about 50 ft above ground level, it seemed like the engine experienced a partial loss of power. The pilot stated that he heard an abnormal noise as the helicopter began to spin to the right, and the low rotor rpm warning light illuminated. The pilot jettisoned the external load line and rolled the throttle toward a closed position in order to counteract the yawing motion, with no response noted. The pilot then initiated an autorotation; during the landing sequence, the helicopter impacted a tree and came to rest upright in a nose-high position. The pilot further stated that, after the helicopter came to rest, he noted that the engine was at a "very slow idle" and he had to shut down the engine. Postaccident examination of the helicopter revealed no evidence of any preexisting mechanical anomalies that would have precluded normal operation. The engine was removed and installed in an engine test cell and ran throughout various power settings. The airframe fuel filter was removed. The filter element was almost black. The fuel removed was dark, and debris was observed within the fuel filter bowl. The fuel sample from the filter housing was tested and found to be within Jet A specifications. The debris noted within the sample contained various metals, the source of which could not be determined. Given that fuel was found throughout the fuel system, it is unlikely that the debris in the filter resulted in a blockage and restriction of fuel flow; however, the reason for the partial loss of engine power could not be determined.

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.