DFW07CA066 · Bell ARH-70 Exp.

The helicopter rolled over during an autorotation following a loss of engine power. The commercial test pilot was performing required test card procedures on the maiden flight of the experimental helicopter. The pilot reported that when he initiated a test flight sequence that called for the helicopter to be configured for slow flight in a shallow descent, the engine low fuel pressure light illuminated followed by an audio alert indicating an engine flame-out. The pilot reported that he immediately entered an autorotation that required a 180-degree turn to the left in order to reach the best available landing area on the fairway of a local golf course. With the helicopter aligned with the intended landing area, the pilot noted that the selected flight path conflicted with a tree on the approach, so the pilot applied collective pitch to slow the rate of descent and clear the tree. As soon as the helicopter cleared the obstacle, the pilot again re-entered a full autorotation. The helicopter touched down in a near level attitude with a slightly faster than normal forward speed. The pilot reported that as the helicopter settled on the golf course fairway, the landing skids began to dig into the soft terrain. The aircraft rocked forward and the toes of the skids dug into the ground, which resulted in the landing gear assembly breaking-off the airframe at all four attachment points and the forward looking infrared mount assembly impacting the ground. The aircraft continued to pivot on the nose and came to rest on its left side, which resulted in structural damage. The investigation revealed that the fuel line to the engine was blocked at the fuel boost pump assembly where the check valve mounts to the fuel switch. Foreign objects were lodged in each of the two check valves, which created a fuel starvation situation and the subsequent engine flame-out.

Verbatim NTSB analysis and probable cause from the NTSB dataset